Fundamental organic chemistry Lab Report

 

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Chem. 230 (Lab Manual)

 

 

 

Faculty of Science

Department of Chemistry

 

 

 

Fundamental Organic Chemistry

 

Edited By:

Abeer Nasser Al-romaizan Hajer Said Al-orfi

Nazeeha Soliman Al-kayal

Under supervision of:

Dr. Nesreen Said Ismail Ahmed

1431 H

  1. word image 3000 Never work alone in the lab.

 

 

 

 

 

 

 

 

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  1. In the lab area do not touch any equipment, chemicals ,or other materials .
  2. Do not drink or eat food and gum in the lab. word image 3002
  3. Always work in a well-ventilated area.
  4. Read carefully instructions of equipment before use .
  5. Keep hands from face, eyes, mouth, and body while using chemicals or lab equipment and wash your hands with soap and water after performing all experimentsK
  6. Contact lenses may be not being worn in the lab.
  7. Long hair must be tied back, and clothing must be secured and shoes must completely cover the foot.
  8. A lab coat, gloves should be worn during lab experiments.
  9. If a chemical should splash in your eyes or on your skin, quickly wash with water for at least 20 minutes.

Toxic substances

 

Flammable substances

Explosive substances

 

harmful substances

oxidizing substances

 

Corrosive substances

 

  1. word image 3003 All chemicals in the lab are dangerous because of that do not taste, or smell any chemicals.

 

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  1. Never return unused chemicals to their original container.
  2. Never remove chemicals or other materials from the lab area.
  3. Examine glassware before each use and never use cracked or dirty glassware.
  4. Do not inter hot glassware in cold water.
  5. Do not operate a hot plate by yourself and take care that hair, clothing, and hands are a safe distance from the hot plate at all times.
  6. Never look into a container that is being heated. word image 3007

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Chemical or causes neutralizing wash or treatment

 

 

Acids 2M ammonium carbonate

Alkalis M acetic acid

Bromine 2M ammonia

Hydro fluoric acid As for acids , then hospital treatment

Phenol Ethanol , then hospital treatment

Phosphorus 0.1 M copper sulphate

Sodium Ethanol on a cotton wool pad

Poison swallowed Plenty of water at once if the patient is conscious Corrosive poisons Plenty calcium hydroxide(lime water) as soon as possible

Gassing In case of gassing acknowledge of artificial respiration method

May be required ,and the correct person(s)to summon should be listed in the emergency procedure

Cuts The wound is washed well with cold water, inspected, And any foreign bodies removed. Then an intersected cream of certrimide is applied and the affected part protected with a suitable dressing

Severe bleeding Firm pressure round the wound, a cover with a pad

And firm bandaging

Electrical mishaps These are usually avoidable by the correct installation

of equipment

First aid in lab

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Test Tube Racks

 

Test Tube

 

Test Tube Brushes

 

Test Tube Holder

 

Litmus Paper

 

Spatulas

 

Glass Stir Rod

 

Ring stands

 

Lab Equipment

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Funnel

 

Dropper

 

Conical flask

 

Beaker

 

Buchner funnel

 

Watch Glass

 

Wash Bottle

 

Cylinder

 

Buchner flask

 

Mortar

 

&

pistil

 

Separating funnel

 

Beaker Tongs

 

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Pipet

 

Bunsen Burner

 

clamp

 

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Evaporating Dish

 

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burette

 

Florence Flask

 

Rubber Stoppers

 

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Filter paper

 

SEPARATION TECHNIQUES

 

Introduction:

Apure substance contains only one kind of molecule; an impure substance is a mixture of molecules. When the different molecules of a mixture each behave in a different way under the conditions of some procedures, the procedure can result in a separation of the different molecules. The theory of each of the separation procedures described in this section is presented from the point of view of the different behavior that can be expected from different molecules under the experimental conditions.

In this part we will discuss the different types of techniques which used for separation of organic compounds.

 

word image 750 Technique 1 Filtration:

Filtration is a technique used for two main purposes. The first is to remove solid impurities from a liquid or a solution. The second is to collect a solid product from the solution from which it was precipitated or crystallized. Two different kinds of filtration are in general use: gravity filtration and vacuum (or suction) filtration.

word image 751 Gravity filtration:

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word image 753 Technique 2

Crystallization:

When a solid organic compound is prepared in the laboratory or isolated from some natural source, such as leaves, it is almost always impure. A simple technique for the purification of such a solid compound is crystallization. The compound is first dissolved in a minimum amount of hot solvent. If insoluble impurities are present, the hot solution is filtered. If the solution is contaminated with colored impurities, it may be treated with decolorizing charcoal and filtered.

 

Crystallization is not the same as precipitation. Precipitation is the rapid formation of solid material, while crystallization is the slow formation of a crystalline solid. If a hot saturated solution is cooled too quickly, then the compound may precipitate instead of crystallizing. A precipitated solute may contain many impurities trapped in the rapidly formed crystal structure. On the other hand, when a solution is allowed to crystallize slowly, impurities tend to be excluded from the crystal structure because the molecules in the crystal lattice are in equilibrium with the molecules in solution.

 

word image 754 Solvents for Crystallization:

The ideal solvent for the crystallization of a particular compound is one that:

  1. Does not react with the compound .
  2. Boils at a temperature that is below the compound’s melting point .
  3. Dissolves a moderately large amount of the compound on hot .
  4. Dissolves only a small amount of compound on cold .
  5. Is moderately volatile so that the final crystals can be dried readily .
  6. Is nontoxic, nonflammable, and inexpensive.

 

In addition, impurities should be either highly insoluble in the solvent else highly soluble, so that they remain in solution during the crystallization.

 

General guidelines for predicting solubilities based upon the structures of organic compounds do exist. For example, an alcohol, a compound containing the hydroxyl (-OH) group as its functional group, may be soluble in water because it can form hydrogen bonds with water molecules. If an alcohol’s molecules are largely hydrocarbon, the alcohol may be insoluble in water, but will probably be soluble in other alcohols, such as ethanol (CH3CH2OH). Carboxylic acids

(compounds containing – CO2H groups) and amines (compounds containing NH2, N H , or N groups) also can form hydrogen bonds and are also generally soluble in polar solvents such as alcohols.

 

Compounds that are largely hydrocarbon in structure are not soluble in polar solvents because C – C and C – H bonds are not polar. For these compounds, we would choose a non polar solvent – for example, low-boiling petroleum ether, which is a mixture of alkanes such as pentane, CH3(CH2)3CH3, and hexane, CH3(CH2)4CH3. Thus, in choosing crystallization solvents, chemists generally follow the rule of thumb: like dissolves like.

 

 

solvent

Bp(OC)

Useful for

water

100

Salts amides some carboxylic acids

methanol

65

General use

ethanol

78

General use

acetone

56

General use

ethylacetate

77

General use

dichloromethane

40

General use

Diethyl ether

35

General use

Chloroform

61

General use

toluene

111

Aromatic compound

benzene

80

Aromatic compound

Hexane(petroleum

ether)

69

hydrocarbons

Table 1: Some common crystallization solvents

 

Ideally, a compound to be crystallized should be soluble in the hot solvent, but insoluble in the cold solvent. When a proper solvent cannot be found, a chemist may use a solvent pair.

word image 755 Steps in Crystallization:

  1. Dissolving the compound. The first step in crystallization is dissolving the compound in a minimum amount of the appropriate hot solvent in an Erlenmeyer flask. An Erlenmeyer flask is used instead of a beaker or other container for several reasons. The solution is less likely to splash out and dust is less likely to get in.

 

Toxic solvents should be heated only in a hood. Safety Note:

 

  1. Filtering insoluble impurities. Filtering a hot, saturated solution inevitably results in cooling and in evaporation of some of the solvent. Therefore, a premature crystallization of the compound on the filter paper and in the funnel may be observed. A few precautions can minimize this premature crystallization.
  2. Crystallizing the compound. Cover the flask containing the hot, saturated solution with a watch glass or inverted beaker to prevent solvent evaporation and dust contamination.
  3. Isolation the crystals. Crystals are separated from their mother liquor by filtration.

 

Suggested experiments:

Crystallize one of the following compounds from the indicated solvents:

  1. benzoic acid from water .
  2. Acetanilide from water . 3) Naphthalene from 95% ethanol .

 

word image 756 Technique 3

Sublimation:

Sublimation is a process whereby a solid is purified by vaporizing and condensing it without its going through an intermediate liquid state.

Solid compounds that evaporate (that is, pass directly from the solid phase to the gaseous phase) are rather rare; solid CO2 (dry ice) is a familiar example of such a compound. Even though both solids and liquids have vapor pressures at any given temperature, most solids have very low vapor pressures.

Sublimation can be used to purify some solids just as distillation can be used to purify liquids. In sublimation, nonvolatile solid impurities remain behind when the sample evaporates, and condensation of the vapor yields the pure solid compound. Sublimation has the advantages of being fast and clean because no solvent is used. Unfortunately, most solid compounds have vapor pressures too low for purification in this fashion. Also, sublimation is successful only if the impurities have much lower vapor pressures than that of the substance being purified.

 

Atmospheric Sublimation:

word image 757 The atmospheric sublimation apparatus shown can be used only for a solid with a relatively high vapor pressure. Place the sample in a filter flask equipped with a water-cooled cold finger or a test tube filled with ice. Warm the flask on a hot plate or in a water bath, taking care not to melt the solid. Crystal growth on the test tube (and on the cooler flask sides) soon occurs. Periodically, cool the apparatus, remove the cold finger or test tube carefully, and scrape the sublimed crystals into a tared container or onto a watch glass. Determine the melting point of the sample with a sealed capillary fig. (3).

 

 

 

Vacuum Sublimation:

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For a vacuum sublimation, choose a side-arm test tube to hold the sample, and then insert a smaller test tube fitted into a neoprene adapter or large-holed stopper. Place ice in the inner tube, connect the side arm with heavy-walled rubber tubing to a trap (preferably chilled in an ice bath) and then to the aspirator.

For an illustration of the trap and a discussion of using the aspirator.

word image 758 Turn on the aspirator and press the test tubes together to obtain a seal. Then, warm or heat the outer test tube. When the sublimation is complete, allow the apparatus to cool before breaking the vacuum. Take care in breaking the vacuum and removing the tube so that the sublimed crystals remain on the tube until they are scraped off. Fig. (4) .

 

 

word image 759 Suggested experiments:

 

  1. Perform an atmospheric sublimation of hexachloroethane .
  2. Vacuum sublime naphthalene or caffeine.

 

 

word image 760 Problems:

Which of the following compounds could be subjected to sublimation at atmospheric pressure?

    1. Compound A:vapor pressure at its melting point=770 mmHg
    2. Compound B:vapor pressure at its melting point=400 mmHg
    3. Compound C:vapor pressure at its melting point=10 mmHg

word image 761 Technique 4

 

Extraction Using a Separatory Funnel:

Extraction is the separation of a substance from one phase by another phase. The term is usually used to describe removal of a desired compound from a solid or liquid mixture by a solvent. In a coffee pot, caffeine and other compounds are extracted from the ground coffee beans by hot water. Vanilla extract is made by extracting the compound vanillin from vanilla beans.

In the laboratory, several types of extraction techniques have been developed. The most common of these is liquid-liquid extraction, or simply “extraction.” Extraction is often used as one of the steps in isolation a product of an organic reaction. After an organic reaction has been carried out, the reaction mixture usually consists of the reaction solvent and inorganic compounds, as well as organic products and by-products. In most cases, water is added to the reaction mixture to dissolve the inorganic compounds. The organic compounds are then separated from the aqueous mixture by extraction with an organic solvent that is immiscible with water. The organic compounds dissolve in the extraction solvent while the inorganic impurities remain dissolved in the water.

word image 762 The most commonly used device to separate the two immiscible solutions in an extraction procedure is the separatory funnel. Typically the aqueous mixture to be extracted is poured into the funnel first, and then the appropriate extraction solvent is added. The mixture is shaken to mix the extraction solvent and the aqueous mixture, and then is set aside for a minute or two until the aqueous and organic layers have separated. The stopcock at the bottom of the separatory funnel allows the bottom layer to be drained into a flask and makes possible the separation of the two layers fig.(5). The result (ideally) is two separate solutions: an organic solution (organic compounds dissolved in the organic extraction solvent), and an inorganic solution (inorganic compounds dissolved in water). Unfortunately, often the water layer still contains some dissolved organic material. For this reason, the water layer is usually extracted one or two more times with fresh solvent to remove more of the organic compound.

After one or more extractions and separations, the combined organic solutions are usually extracted with small amounts of fresh water to remove traces of inorganic acids, bases, or salts; treated with a solid drying agent to remove traces of water; and then filtered to remove the hydrated drying agent. Finally, the solvent is evaporated or distilled. The organic product can then be purified by a technique such as crystallization or distillation.

 

Distribution Coefficients:

When a compound is shaken in a separatory funnel with two immiscible solvents, such as water and diethyl ether (CH3CH2OCH2CH3), the compound distributes itself between the two solvents. Some dissolves in the water and some in the ether. How much solute dissolves in each phase depends on the solubility of the solute in each solvent. The ratio of the concentrations of the solute in each solvent at a particular temperature is a constant called the distribution coefficient or partition coefficient (K).

Concentration in solvent2

K = ——————————— Concentration in solvent1

Where solvent1 and solvent2 are immiscible liquids.

 

Steps in extraction:

  1. Preparation of the separatory funnel.
  2. Adding the liquids.Be sure the stopcock is closed.

Safety Note:

Never add a volatile solvent to a warm solution. If you are using a flammable solvent, make sure there are no flames in the vicinity!

  1. Mixing the layers.

Insert the stopper and, holding the stopper in place with one hand, pick up the separatory funnel and invert it. Immediately open the stopcock with your other hand to vent solvent fumes or carbon dioxide. Swirl the separatory funnel gently to further drive off solvent vapors or gases.

word image 763 word image 764 After venting, close the stopcock, gently shake or swirl the mixture in the inverted funnel, then re-vent the fumes. If excessive pressure build-up is not observed, the separatory funnel and its contents may be shaken up and down vigorously in a somewhat circular motion for 2-3 minutes so that the layers are thoroughly mixed. Vent the stopcock several times during the shaking period. After completing the shaking, vent the stopcock one last time. Place a large Erlenmeyer flask under the stem of the separatory funnel in case the stopcock should develop a leak. Allow the separatory funnel to sit until the layers have separated.

  1. Separation the layers. Before proceeding, make sure the stopper has been removed. (It is difficult to drain the lower layer from a stoppered funnel. Because a vacuum is created in the top portion of the funnel.)

 

  1. word image 765Cleaning the separatory funnel.

Suggested experiments:

  1. Separate a mixture of 2-naphthol and benzoic acid by an ether-bicarbonate extraction.
  2. Separate a mixture of benzoic acid, p-chloroaniline, and naphthalene using dichloromethane as the organic solvent.

Technique 5

Chromatograph:

Chromatography is a general term that refers to a number of related techniques used for analyzing, identifying, or separating mixtures of compounds. All chromatographic techniques have one principle in common liquid or gaseous solution of the sample, called the mobile phase, is passed (moved) through an adsorbent, called the stationary phase. The different compounds in the sample move through the adsorbent at different rates because of physical differences (such as vapor pressure)and because of different interactions (adsorptivities, solubilities. etc.)with the stationary phase.

 

1- Column Chromatography

Column chromatography is used to separate mixtures of compounds. In this technique, a vertical glass column is packed with a polar adsorbent along with a solvent. The sample is added to the top of the column; then, additional solvent is passed through the column to wash the components of the sample, one by one (ideally), down through the adsorbent to the outlet.

The sample on the column is subjected to two opposing forces: the solvent dissolving it and the adsorbent adsorbing it. The dissolving and the adsorption constitute an equilibrium process, with some sample molecules being adsorbed and others leaving the adsorbent to be moved along with the solvent, only to be re-adsorbed farther down the column. A compound (usually a non polar one) that is highly soluble in the solvent, but not adsorbed very strongly, moves through the column relatively rapidly. On the other hand, a compound (usually a more polar compound) that is more highly attracted to the adsorbent moves through the column more slowly.

Because of the differences in the rates at which compounds move through the column of adsorbent, a mixture of compounds is separated into bands .

 

 

 

 

 

 

  1. word image 766 The sample has just started to move into column of adsorbent .
  2. and (3) as more solvent is passed through the column, the sample moves down and begins to separate into its components because of differences in attraction to the adsorbent and solvent.

(4) The faster-moving compound is eluted into a flask.

 

word image 767 Suggested experiments:

 

  1. Separatec a mixture of permanganate and dichromate on silica gel column.
  2. Isolate and separate plant pigments from extracts of carrots, tomatoes ,etc.
  3. Separate o-and p-nitro anilines.

 

 

2- Thin-Layer Chromatography(TLC)

Thin-layer chromatography is a variation of column chromatography. Instead of a column, a strip of glass or plastic is coated on one side with a thin layer of alumina or silica gel.

In a TLC analysis, about 10 µL of a solution of the substance to be tested is placed (“spotted”) in a single spot near one end of the plate, using a micro capillary. The plate is “developed” by placing it in a jar with a small amount of solvent. Shows a TLC plate in a developing jar. The solvent rises up the plate by capillary action, carrying the components of the sample with it. Different compounds in the sample are carried different distances up the plate because of variations in their adsorption on the adsorbent coating. If several components are present in a sample, a column of spots is seen on the developed plate, with the more polar compounds toward the bottom of the plate and the less polar compounds toward the top.

As an analytical tool, TLC has a number of advantages: it is simple, quick, inexpensive, and requires only small amounts of sample. Tlc is generally used as a qualitative analytical technique, such as checking the purity of a compound or determining the number of components in a mixture. We can use TLC to follow the course of a reaction by checking the disappearance of starting material.

 

 

 

 

The Rf Value:

 

 

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Fig.(7):Thin-layer Chromatography.

 

The distance that the spot of a particular compound moves up the plate relative to the distance moved by the solvent front is called the retention factor, distance traveled by the compound

Rf= ——————————————– distance traveled by the solvent

 

Equipment for TLC:

TLC sheets and plates. Commercial TLC sheets are coated with silica gel (SiO2) or alumina (Al2O3). Choose the type that gives the best separation for your particular mixture.

If commercial TLC sheets are unavailable, plates can be made from microscope slides and a slurry of 1g aluminum oxide G or silica gel G and 2mL chloroform (CAUTION : toxic). A 2 : 1 mixture by volume of dichloromethane and methanol (also toxic) may be substituted for the chloroform.

Dip two slides, back-to-back, in the slurry. Allow the excess slurry to drain. Separate the slides and allow them to dry in a fume hood. Then wipe excess adsorbent from the backs and edges of the slides. Making satisfactory plates requires practice; therefore, prepare a number of plates and select the most evenly coated ones. Microscope slide plates are shorter than commercial sheets; consequently, the separation of components is not as clean.

Pipets. Commercial 10- µL disposable pipets are best for spotting. If commercial pipets are not available, draw out some soft glass tubing or melting-point capillary tubes in a flame. The diameter of the pipet should be about 1/4 of the diameter of a melting-point capillary.

Developing jars. Developing chambers with the proper solvent system may be prepared in advance and kept in the fume hood. Any tall jar, such as an instant coffee jar or mason jar, with a lid or screw top, may be used for developing a TLC plate. The jar should be narrow enough to hold the plate upright inside, without the danger of its falling over. The lid of the jar should be impervious to solvent fumes.

 

word image 769 Suggested experiments:

 

  1. Analyze a mixture of amino acids.
  2. Analyze a mixture of ink.

 

word image 770 Problems:

1- Calculate the Rf values for the following compounds:

  1. Spot,5 cm; solvent front, 20cm
  2. Spot,3 cm; solvent front,12 cm
  3. Spot,9.8cm;solvent front,12cm

Technique 6 Distillation:

Distillation is a general technique used for removing a solvent, purifying a liquid or separation the components of a liquid mixture. In distillation, liquid is vaporized by boiling, then condensed back to a liquid, called the distillate or condensate, and collected in a separate flask.

 

Types of distillation:

1-Fractional distillation

Miscible liquids are much more difficult to separate. Mixtures of miscible liquids can be separated by fractional distillation. It will provide the boiling points of the liquids are not too close.

word image 771 If we want to separate a mixture of ethanol and water. The diagram below is suitable for this process. The fractionating column is packed with glass bead. It provides a large surface area for vaporization and condensation of the liquid mixture.

Ethanol is more volatile than water, since it has a lower boiling point (78oC). The vapor rises up the fractionating column when the mixture is heated. Because ethanol is more volatile, the vapor contains more ethanol. The hot vapor condenses upon touching the cold glass beads. There is a continues rise of hot vapor up the fractionating column at the same time. Hot vapor will make the condensed vapor boils again. It will contain more and more ethanol as the vapor rises up to the fractionating column.

 

 

The above process is to be repeated many times before the vapor consists only pure ethanol. During the process the escaping vapor is measured by a thermometer of the fractionating column. The temperature will remain steady for some time and will then rise quickly and become pure ethanol.

When the ethanol has boiled off completely, the escaping vapor will consist of pure water only.

Generally, for fractional distillation to work best, the difference in boiling points of liquids in the mixture should be greater than 10C. The separation will not be complete if it is not.

Fractional distillation is used in industry to separate oxygen and nitrogen from liquid air. In whisky production it is used to increase ethanol.

 

2-Vacuum distillation

Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure (usually less than atmospheric pressure) causing evaporation of the most volatile liquid(s) (those with the lowest boiling points). This distillation method works on the principle that boiling occurs when the vapor pressure of a liquid exceeds the ambient pressure. Vacuum distillation is used with or without heating the solution

 

 

3-Steam distillation

 

Fig.(9): Steam distillation

 

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Steam distillation is a special type of distillation (a separation process) for temperature sensitive materials like natural aromatic compounds.

Many organic compounds tend to decompose at high sustained temperatures. Separation by normal distillation would then not be an option, so water or steam is introduced into the distillation apparatus. By adding water or steam, the boiling points of the compounds are depressed, allowing them to evaporate at lower temperatures, preferably below the temperatures at which the deterioration of the material becomes appreciable. If the substances to be distilled are very sensitive to heat, steam distillation can also be combined with vacuum distillation. After distillation the vapors are condensed as usual, usually yielding a two-phase system of water and the organic compounds, allowing for simple separation.

 

When a mixture of two practically immiscible liquids is heated while being agitated to expose the surfaces of both the liquids to the vapor phase, each constituent independently exerts its own vapor pressure as a function of temperature as if the other constituent were not present. Consequently, the vapor pressure of the whole system increases. Boiling begins when the sum of the partial pressures of the two immiscible liquids just exceeds the atmospheric pressure (approximately 101 kPa at sea level). In this way, many organic compounds insoluble in water can be purified at a temperature well below the point at which decomposition occurs. For example, the boiling point of bromobenzene is 156 °C and the boiling point of water is 100 °C, but a mixture of the two boils at 95 °C. Thus, bromobenzene can be easily distilled at a temperature 61 C° below its normal boiling point.

Steam distillation is employed in the manufacture of essential oils, for instance, perfumes. In this method, steam is passed through the plant material containing the desired oils. It is also employed in the synthetic procedures of complex organic compounds. Eucalyptus oil and orange oil are obtained by this method on the industrial scale.

 

 

Test

Observation

Result

1-Bromination Test :

In two test tubes put 1ml of cyclohexane +1ml of bromine and shake both well. Protect one from light and expose the second to sun light for 15 min.

 

The orange color of bromine is not disappears from the first tube.

The color of the second tube disappears.

It is saturated compound formed via displacement reaction by the effect of sunlight (1).

Br

 

h v

 

+ Br2 ………(1)

 

Cyclohexane Bromine 1-Bromocyclohexane

 

 

*********************************************** HYDROCARBONS

 

Compound containing only Carbon and Hydrogen and classified into:

Alkanes R-H

  • Alkanes are saturated hydrocarbon compounds.
  • Chemically, alkanes are unreactive compounds because they are saturated compounds , all the bonds are strong sigma bonds.
  • The general formula of alkanes is CnH2n+2
  • Example: Cyclohexane

 

 

2- Potassium Permanganate Test: In a test tube put 1ml of cyclohexane + few drops of dilute acidic KMnO4 with shaking.

 

The violet color of the

KMnO4 dose not changes.

 

It is saturated compound.

 

OH

H2SO4 conc.

+

Cyclohexanol Cyclohexene

H2O

 

Alkenes R-CH=CH-R

 

  • Alkenes are unsaturated hydrocarbon compounds containing double bond .
  • They are reactive compounds because they contains weak π bond .
  • The general formula of alkenes is CnH2n .
  • Example: Cyclohexene

 

word image 772 Preparation of cyclohexene:

 

Put 3ml of cyclohexanol in dry test tube + 0.5 ml of conc. H2SO4 (2) and then perform the following tests:

 

 

…..(2)

 

 

 

word image 773

Alkynes (Acetylenes)

Ca

C

C

+

2

H

2

O

H

C

C

H

+

Ca(OH)

2

  • Alkynes are unsaturated hydrocarbon compounds containing triple bond .
  • The alkynes are also reactive compounds because they contains weak π bonds .
  • The general formula of alkynes is CnH2n-2
  • Example: Acetylenes HC CH

 

word image 774 Preparation of Acetylene:

 

Acetylene gas prepared by adding water to calcium carbide CaC2 (5)

 

 

….. (5) …(5)

 

 

word image 775 Procedure:

Put 0.25 gm from calcium carbide in dry test tube add 1ml of water and note the evolution of acetylene gas, perform the following

experiments on it:

 

Test

Observation

Result

 

1-Bromination Test :

Pass the acetylene gas on the test tube contains bromine.

 

The orange color of the bromine disappears Immediately.

 

It is unsaturated compound (6).

HC

 
 
 

CH

HC

CH

Br

2

Br

2

Br Br

 

Br

 

Br

 

…(6)

HC

Br

CH

Br

2- Potassium Permanganate Test :

Pass the acetylene gas on the test tube contains dilute acidic KMnO4 with shaking.

 

 

The violet color of the

KMnO4 disappears immediately .

 

 

It is unsaturated

compound.

3- Pass the acetylene gas on the test tube contains ammonical silver nitrate.

White precipitate forms.

The white precipitate is Silver acetylide (7).

 

 

Ag

 

HC CH + 2 Ag + C + 2 H+

Ag

C

 

Silver acetylide …(7)

 

Test

Observation

Result

1-Nitration Test : In a test tube put 1ml of

conc.HNO3 acid + 1ml of conc. H2SO4 acid + 0.5ml of benzene then pour into beaker contains cold

water .

 

 

 

Yellow oily layer will be separated

 

 

The yellow oily layer is Nitro benzene (8).

AROMATIC HYDROCARBONS

CH

3

 

 

 

 

Examples on Aromatic hydrocarbons:

 

 

 

Benzene Toluene

The most characteristic reactions for aromatic hydrocarbons are:

  1. Nitration reaction
  2. Sulphonation reaction

 

1-Benzene

Benzene is a colorless liquid , immiscible in water but miscible in all organic solvent, flammable and burned by heavy smoked yellow flame which indicate that it rich with carbon .

2 4

 

HNO

3

Conc.

H

SO

 

Conc

.

Nitrobenzene

NO2

+ H2O

…(8)

 

Test

Observation

Result

 

1-Nitration Test : In a test tube put 1ml of conc.HNO3 acid + 1ml of conc. H2SO4 acid + 0.5ml of Toluene then pour into beaker contains cold water .

 

 

 

Yellow oily layer will be separated

 

 

The yellow oily layer is oNitrotoluene

& p-Nitrotoluene (9).

 

 

HNO

3

Conc.

CH

3

 

CH

3

CH

3

+

NO

2

NO

2

H

2

SO

4

 

Conc

.

….(9)

oNitrotoluene p-Nitrotoluene

CH3

2-Toluene

 

Toluene is a color less liquid , the boiling point is 110°C immiscible in water but miscible in organic solvent behave like benzene on burning .

 

 

 

ALCOHOLS COMPOUNDS

 

R

OH

 

 

  • Alcohols are compounds contains one or more hydroxyl groups (OH)

C

O

  • Alcohols divided according to the type of carbon atom attached to the hydroxyl group in the molecule to Primary, Secondary& Tertiary alcohols.

 

Oxidation test:

It was found that Primary alcohols oxidizing to aldehyde the Secondary alcohols oxidizing to ketone, but tertiary alcohols not oxidized according to the following equations.

 

RCH

2

OH

C

H

R

O

[

]

 

[ O ]

O

R

C

OH

O

 

Primary alcohol aldehyde carboxylic acid

 

[ O ]

R CHOH R R

2

Secondary alcohol Ketone

 

R3COH [ O ] No reaction

Tertiary alcohol

1-Methanol CH3OH

 

Methyl alcohol is colorless liquid , have characteristic odor , miscible in water , toxic , burned by blue flame .

 

 

Test

 

Observation

 

Result

1-Oxidation Reaction:

In a test tube put 1 ml of methanol

+1ml of potassium dichromate

K2Cr2O7 + drops of conc. sulphuric acid .

 

The orange color of the solution changes to green.

 

The green color is chromium

sulphate Cr2(SO4 )3 which

formed due to the oxidation of methanol to Formaldehyde (10).

K2Cr2O7 + 4 H2SO4 + 3 CH3OH

3

H

 

O

 

H + K2SO4 + Cr2(SO4)3 + 7 H2O

… (10)

 

C

 

2-Esterification :

In a test tube put 1ml of methanol + 0.5 gm of salicylic acid + drops of conc. H2SO4 & heat in water bath for 3 min. then cool and pour the content of the test tube into beaker contains Na2CO3 .

 

Vix (oil of winter green ) odor appear.

 

The product is methyl salicylate (11).

 

COOHCOOCH3

H

2

SO

4

Conc

.

OH + CH3OHOH + H2O

 

methyl salicylate … (11)

41

2-Ethanol CH3CH2OH

 

Ethyl alcohol is colorless liquid , have characteristic odor , miscible in water , toxic , burned by colorless flame .

 

 

Test

 

Observation

 

Result

1-Oxidation Reaction:

In a test tube put 1ml of ethanol +1ml of potassium dichromate

K2Cr2O7 + drops of conc. sulphuric acid .

 

The orange color of the solution changes to green.

 

The green color is chromium

sulphate Cr2(SO4 )3 which

formed due to the oxidation of ethanol to acetaldehyde (12 )

K2Cr2O7 + 4 H2SO4 + 3 CH3CH2OH 3 CH3

 

O

 

H + K2SO4 + Cr2(SO4)3+ 7H2O chromium sulphate … (12)

C

 

2-Esterification :

In a test tube put 1ml of ethanol

+ 0.5 gm of sodium acetate + drops of conc. H2SO4 & heat in water bath for 3 min. then cool and pour the content of the test tube into beaker contains Na2CO3 solution .

 

 

Fruity odor appears (apple odor) .

 

 

The product is

Ethyl acetate (13) .

 

42

 
 

H SO CH3COONa + CH3CH2OH 2 4 conc. CH3COOCH2CH3 + NaOH ..(13)

Ethyl acetate

 

3-Iodoforms Test :

In a test tube put 1ml of ethanol + 3ml of iodine solution & heat in water bath for 3 min. then cool & add NaOH drop wise till the color is straw yellow a pale yellowish ppt. of iodoform is produced.

 

 

Yellow ppt. formed.

 

 

 

 

The yellow ppt. is Iodoform

CHI3 (14) .

 

 

 

O O

[

O

]

C

H

CI

 

3

I

2

CH

NaOH

CH3CH2OH 3 3 C H CHI3 + HCOONa …(14)

– 3 HI

Iodal Iodoform

 

 

 

 

 

 

 

 

 

 

 

 

43

CH2 OH

3-Glycerol CH OH

 

CH2 OH

 

Glycerol is a colorless viscous liquid, melted at 10 °C, miscible in water and alcohol and has a sweet taste.

The most characteristic test for glycerol is the Borax test.

 

Test

 

Observation

 

Result

1-Borax Test :

In a test tube add 2 drops of phenolphthalein (ph.ph) to dilute borax solution then a pink color is produced Add few drops of glycerol & shake.

 

The color disappears and is restored on heating.

 

The disappearance of (ph.ph) color on cold due to the formation of strong acid and by heating this acid dissociated into boric acid & glycerol , the pink color returned (15) .

 

Na2B4O7 7H+ 2O 2 NaOH 4 H+ 3BO3

CH OH

 

CH

2

O

CH

O

CH

2

OH

O

B

Cold

Hot

2

CH

HO

OH + OH H + + H2O

B

HO

CH2 OH

Glycerol Boric acid Strong acid …(15 )

 

 

{ Basic Media } Pink colour { Acidic Media } colourless

 

CARBONYL COMPOUND

 

 

 

1-Aldehydes 2-Ketones

 

 

  • Aldehydes are produced by oxidation of primary alcohols,
  • Ketones produced from oxidation of secondary alcohols.

Examples:

 

 

O O O

H3C C H ; H3C C CH3 ; H

C

Acetaldehyde Acetone Benzaldehyde

 

 

 

 

****************************

 

 

 

 

 

1-Formaldehyde H

H

C

O

 

Formaldehyde is a gas and is available as aqueous solution which has a characteristic pungent odor.

 

Test

 

Observation

 

Result

 

2,4-dinitrophenyl hydrazine test:

In a test tube put 1 ml of HCHO +1ml of 2,4- dinitro phenyl hydrazine .

 

 

Yellow precipitate is formed.

 

The ppt. is hydrazone derivative this prove that formaldehyde contain carbonyl group (16) .

 

H

NHNH2 ++ H2O

O

C

H

H

2

O

NHN

O

2

N

C

H

O

2

N

H

NO2 NO2

 

2,4-dinitrophenyl- hydrazine Formaldehyde Hydrazone derivative …(16)

2-Schiff’s Reagent:

In a test tube put 1 ml of HCHO + drops of Schiff’s reagent.

 

Magenta color appears rapidly.

 

It’s Formaldehyde

3-Reduction Reaction

A)– Ammonical AgNO3

In a test tube put 1ml of HCHO +3 ml of amm. AgNO3 & heat in water bath for 3 min.

A silver mirror is deposited on the inner wall of the test tube.

 

Due to Oxidation of

HCHO to formic acid

& reduction for Ag2O to Ag metal (17).

O O

H C H + Ag2O H C OH + 2Ag ….(17)

formaldehyde formic acid silver metal

 

 

B)– Fehlings solution

In a test tube put 1ml of HCHO +1ml of Fehling solution A +1ml of Fehling solution B & then heat on water bath for 3 min.

 

 

Solution turns green and after some time a red ppt.

 

Due to Oxidation of

HCHO to formic acid

& reduction for CuO to

Cu2O (red ppt.) (18)

 

O O

H C H + 2CuO H C OH + Cu2O ….(18)

formaldehyde formic acid

 

4-Resorcinol Test :

In a test tube put 1ml of HCHO

+ drops of resorcinol +1ml of H2SO4 conc. added down the side of the test tube.

 

Red violet ring is formed & white ppt.

appears over the ring.

 

 

The aldehyde is Formaldehyde.

 

 

 

 

 

 

 

2-Acetaldehyde CH3 C H

O

 

It is a liquid b.p 21° generally used in aqueous solution which has also characteristic odor , miscible in water ,alcohol and ether .

 

Test

 

Observation

 

Result

 

1-2,4-dinitrophenyl hydrazine test :

In a test tube put 1ml of CH3CHO

+1ml of 2,4-dinitro phenyl hydrazine

 

Yellow precipitate is formed.

 

The ppt. is hydrazone derivative this prove

that acetaldehyde contain carbonyl group

 

2-Schiff’s Reagent:

In a test tube put 1 ml of CH3CHO + drops of Schiff’s reagent.

 

Magenta Violet color appears rapidly.

 

 

It’s Acetaldeyde

3-Reduction Reaction

A)– Ammonical AgNO3

In a test tube put 1ml of CH3CHO + 3 ml of amm. AgNO3 & heat in water bath for 3 min.

 

A silver mirror is

deposited on the inner wall of the test tube.

 

Due to Oxidation of

CH3CHO to acetic acid

& reduction for Ag2O to Ag metal .

B)– Fehlings solution

In a test tube put 1ml of CH3CHO

+1ml of Fehling solution A +1ml of Fehling solution B & then heat on water bath for 3 min .

 

Solution turns green and after some time a red ppt.

 

Due to Oxidation of

CH3CHO to acetic acid

& reduction for CuO to

Cu2O (red ppt.)

 

4-Aldol Condensation

In a test tube put 1ml of CH3CHO

+3ml of NaOH then boiling 2 min.

 

 

Colloidal Yellow ppt. is formed.

 

The precipitate is 2-butenal (19).

 

NaOH

2 CH3CHO CH3CH CH CHO

2-butenal …(19)

 

5-Iodoform Test :

In the test tube put 1ml of CH3CHO + 3ml of Iodine &heat on water bath for 3 min. then cool & add drop wise of NaOH until the iodine color disappear

 

 

Yellow ppt. is formed

 

 

The Yellow ppt. is

Iodoform CHI3 (20)

O O

CI

 

3

I

2

NaOH

CH3 C H 3 C H CHI3 + HCOONa …(20)

– 3 HI

Iodal Iodoform

 

6-Sodium nitroprusside Test:

In the test tube put 1ml of CH3CHO + 0.5 ml of Sodium nitroprusside then put drops of NaOH with shaking .

 

 

Dark red color

 

It’s Acetaldehyde

 

 

 

C

O

3-BenzaldehydeH

 

Benzaldehyde is colorless liquid if pure with the odor of bitter almonds immiscible with water & sinks in it but miscible with alcohol .

 

Test

 

Observation

 

Result

 

1-2,4-dinitrophenyl hydrazine test: In a test tube put 1ml of benzaldehyde +1ml of 2,4-dinitro phenyl hydrazine .

 

Dark yellow

precipitate is formed.

 

The ppt. is hydrazone derivative this prove that benzaldehyde contain carbonyl group

 

2-Schiff’s Reagent:

In a test tube put 1 ml of benzaldehyde + drops of Schiff’s reagent.

magenta color

appears after some time and vigorous shaking .

 

 

It’s benzaldehyde

3-Reduction Reaction

A ) Ammonical AgNO3

In a test tube put 1ml of benzaldehyde + 3 ml of amm. AgNO3 & heat in water bath for 3 min.

 

A silver mirror is

deposited on the inner wall of the

test tube by gentle heating.

 

Due to Oxidation of benzaldehyde to benzoic acid

& reduction for

Ag2O to Ag metal .

 

 

B) Fehlings solution

In a test tube put 1ml of benzaldehyde

+1ml of Fehling solution A +1ml of Fehling solution B & then heat on water bath for 3 min

 

Solution turns green and after some time a red ppt.

 

Due to Oxidation of benzaldehyde to

benzoic acid &

reduction for CuO to Cu2O (red ppt.) .

 

 

4-Cannizzaro Reaction

In a test tube put 1ml of benzaldehyde + 3ml NaOH 30% & heat on water bath for 3 min. then add drops of H2O and drops of HCl Conc.

 

 

White ppt. is formed

 

 

The white ppt. is benzoic acid (21).

 

+ ……(21)

C

O

H

NaOH

COONa

CH2OH

Sodium benzoate Benzyl alcohol

HCl

COOH

NaCl +

White ppt.

 

 

 

O

4-Acetone CH 3 C CH3

Acetone is colorless liquid with a characteristic odor, inflammable, miscible with water, alcohol & ether .

 

Test

 

Observation

 

Result

 

1-2,4-dinitrophenyl hydrazine test:

In a test tube put 1ml of acetone

+1ml of 2,4-dinitrophenylhydrazine

 

Yellow precipitate is formed.

 

The ppt. is hydrazone derivative this prove that acetone contain carbonyl

group .

2-Schiff’s Reagent:

In a test tube put 1 ml of acetone + drops of Schiff’s reagent.

magenta color appears slowly, need long time

 

Acetone is ketone not aldehyde .

3-Iodoform Test :

In the test tube put 1ml of acetone

+3ml of Iodine then add drops of NaOH immediately.

 

Yellow ppt. is formed

on cold.

 

The Yellow ppt. is

Iodoform CHI3 (22) .

CH3

O

 

 

3 I2 NaOH

CH

3

CH3COC I3 C HI3 + CH3COONa

3 HI

Iodal Iodoform… (22)

C

4 – Sodium nitroprusside Test:

In the test tube put 1ml of acetone + 0.5 ml of Sodium nitroprusside then put drops of NaOH with shaking.

 

Deep Red Solution

Formed.

 

It’s Acetone characteristic test for

(- COCH3).

CARBOXYLIC ACIDS

Liquid organic acids

 

 

  • All acids contains carboxyl group COOH.
  • Acids divided into two major classes.

Aliphatic acid and aromatic acid. Also can divide into different types according to number of carboxylic group in the molecules or according to type or number of another group attached to acid molecules.

 

Aliphatic acids :

word image 3052 word image 3053 word image 3054 word image 3055 word image 3056 word image 3057 word image 3058 word image 3059 word image 3060 word image 3061 word image 3062 word image 3063 word image 3064 word image 3065 word image 3066

COOH HOCOOH

CH

CH

HCOOH CH3COOH COOH HO COOH

formic acid

Acetic acid

oxalic acid Tartaric acid

Aromatic acid:

word image 3067 word image 3068 word image 3069 word image 3070 word image 3071 word image 3072 word image 3073 word image 3074 word image 3075 word image 3076 word image 3077 word image 3078 word image 3079 word image 3080 word image 3081

COOH

COOH

OH

 

Benzoic acid Salicylic acid

Neutral Solution of acid:

word image 3082 word image 3083 word image 3084 word image 3085 word image 3086 word image 3087 word image 3088 word image 3089 word image 3090 word image 3091 word image 3092 word image 3093 word image 3094 word image 776

N.S of acid is the ammonium salt for acid

RCOOH + NH4OH RCOONH4 + H2O

word image 777

Some chemical reactions used to identify such acids carried out on its N.S.

word image 778 To Make Neutral Solution N.S.:

 

Add to the acid aqueous NH3 (NH4OH) till the solution is just alkaline to litmus. Boil the solution until the evolution of NH3 gas ceases ( this can be ensured by exposing a red litmus paper to vapor ) .

 

General properties for acids :

  1. Soluble in sodium hydroxide.
  2. Soluble in sodium carbonate or sodium bicarbonate with eff. of CO2 gas.
  3. When heated the acids with sodalime CO2 evolved.

 

COOH

 

word image 779

CaO/NaOH

heat

+ CO2

 

COOH OH

+ CO2

OH

heat

CaO/NaOH

word image 780

 

  1. Acids react with alcohol in present of conc. H2SO4 produce ester with specific odor .

 

‘ H2SO4 ‘ ‘

RCOOH + ROH RCOOR + H2O

word image 781 word image 782

 

  1. N.S of acid with ferric chloride solution. Gives specific color for each acid.
  2. Acids Solution turns litmus paper to red.

 

1- Formic acids HCOOH

Formic acid is a colorless liquid, immiscible in water, alcohol and ether.

It has a pungent irritating odor. All formate as soluble except those of Ag, Hg, and some basic salt.

 

Test

 

Observation

 

Result

 

1-Acidity test:

1ml of acid +2ml of NaHCO3

 

CO2 evolves with effervescence.

 

Compound is carboxylic

acid (23).

 

HCOOH + NaHCO3 HCOONa + H2O + CO2

Sodium formate … (23)

2-Ferric chloride test:

1ml of N.S. of acid + few drops of FeCl3 .

Red color turned with heating into Brown ppt.

Red color is ferric format

(HCOO)3 Fe and brown ppt. is basic ferric formate

(HCOO) Fe (OH) 2 (24).

 

3 HCOONH4 + FeCl3 (HCOO)3Fe + 3NH4Cl

word image 783

2H2O

word image 784

(HCOO)3Fe(HCOO)Fe(OH)2

 

basic ferric formate … (24)

3-Mercury chloride test:

1ml of N.S. of acids +1ml

HgCl2 & added excess then boil

White ppt. immediately appear &change to gray ppt. with boiling .

White ppt. is Hg2Cl2 & the gray ppt. is metallic Hg (25).

 

2 HCOOH4 + 2 Hg2Cl2Hg2Cl2 + CO + CO2 + 2NH4Cl + H2O

word image 785

 

 

Hg2Cl2 HCOONH+ 4 2 Hg CO CO+ + 2 NH+ 2 4Cl H+ 2O2

word image 786

…..(25)

 

4-Permanganate test: 1ml of warm acids + drops of

KMnO4 .

 

The color of KMnO4 will disappear .

 

Oxidation for formic acid

(26).

 

(O)

HCOOH CO2 + H2O

word image 787

… (26)

5-Esterification test:

In dry test tube but 1ml of acids +1ml of ethanol +1ml of conc.

H2SO4 & then heat in water bath for 3 min., then pour into beaker contain Na2CO3 solution .

 

Pleasant odor is detected

 

 

The odor due to the formation Ethyl formate

HCOOC2HS (27)

 

 

H2SO4

HCOOH + CH3CH2OH HCOOCH2CH3 + H2O

word image 788word image 789

 

 

Ethyl formate … (27)

 

2- Acetic acid CH3COOH

Acetic acid is a colorless liquid, with a penetrating odor of vinegar , miscible with H2O, alcohol and ether . Most of its salts soluble with water except those of Ag, mercurous and basic salts.

 

Test

 

Observation

 

Result

 

1-Acidity test:

1ml of acid + 2ml of NaHCO3.

 

CO2 evolves with effervescence.

 

Acetic acid is carboxylic

acid (28).

 

CH

word image 790

3COOH NaHCO+ 3 CH3COONa H+ 2O CO+ 2

Sodium acetate …(28)

 

2-Ferric chloride test : 1ml of N.S. of acid + few drops of FeCl3.

 

Red color turn with heating to brown ppt.

 

Red color is Ferric acetate (CH3COO)3 Fe and brown

ppt. is basic ferric acetate

(CH3COO) Fe (OH)2 (29)

 

3 CH3COONH4 FeCl+ 3 (CH3COO)3Fe 3NH+ 4Cl

 

2H2O

(CH3COO)3Fe (CH3COO)Fe(OH2)

Basic ferric acetate

 

…(29)

 

3-Mercury chloride test

1ml of N.S. of acids +1ml of HgCl2 & added excess then boil .

 

White ppt. Change to yellow ppt. with boiling.

 

Confirmatory test for acetic acid.

4-Permanganate test:- 1ml of warm acid + drops of

KMnO4 .

 

The color will not disappear .

 

No oxidation for acetic acid occur.

5-Esterification test: In dry test tube put 1ml of acids +1ml of ethanol

+1ml of conc. H2SO4 & heat in water bath then pour into

beaker contain Na2CO3 solution .

 

apple odor

 

This odor characteristic for Ethyl acetate

CH3COOC2H5 (30) .

 

 

H2SO4

CH3COOH CH+ 3CH2OH CH3COOCH2CH3 H+ 2O

word image 791

 

Ethyl acetate …(30)

 

3-Lactic acid CH3CH(OH)COOH

Is light yellow color liquid , frozen at 110°C miscible with water and alcohols .

 

Test

 

Observation

 

Result

 

1-Acidity test:

1ml of acid +2ml of NaHCO3.

 

CO2 evolves with effervescence.

 

Lactic acid is from carboxylic acid .

 

CH3 CH COOH + NaHCO3 CH3 CH COONa +CO2 + H2O

word image 792

OH OH

Sodium lactate … (31)

2-Ferric chloride test:

1ml of N.S. of acid+ few drops

of FeCl3.

 

No change for FeCl3

color.

 

The acid is lactic acid specific test for lactic acid

3-Iodoform test:

1ml of acid + 3ml of iodine then add NaOH with shaking

 

Yellow ppt. is formed on cold .

 

Yellow ppt. is Iodoform

CHI3 (32) .

OH

CH3CHCOOH CI CCOOH 2NaOH CHI3 + COONa

[

O

]

CH

3

CCOOH

O

3

I

2

3

O

-3HI COONa

Iodoform

…(32)

4-Permanganate test:-

1ml of warm acids + drops of

KMnO4 .

 

The color of

KMnO4 disappear .

 

oxidation for hydroxyl group in lactic acid .

Scheme for liquid organics

word image 3095

 

First: 1ml of unknown + drops of Schiff’s reagent

 

Violet color

  • Ve

Unknown is Formaldehyde or Acetaldehyde

Unknown is not aldehyde

Confirmatory test for Formaldehyde

Go to second step and Acetaldehyde

 

 

 

 

 

Second: 1ml of unknown +

1

ml of

Na

2

CO

3

 

solution

 

CO2 evolves with effervescence

  • Ve

Unknown is carboxylic acid

Go to the Third step

1

ml

 

of

 

N.S

.

 

for acid

+

 

drops

 

of

 

FeCl

3

 

 

  • Ve Red color turn by heating to

brown ppt. unknown is formic

Lactic acid acid or acetic acid

Confirmatory test for formic

and acetic acid

 

 

 

Third: 1ml of unknown + 3ml of iodine then add

NaOH gradually

 

by

 

continuous shaking

  • Ve Yellow ppt. from Idoform

Go to the fourth step Unknown is Acetone

 

 

 

 

Forth: 1ml of unknown + 3ml of iodine and heated in water bath for 3min.

then cool and add NaOH gradually by continuous shaking

 

 

 

– Ve

Go to the fifth step

 

Yellow ppt. from Idoform unknown is Ethanol

 

 

 

Fifth: 2ml of borax

 

solution + drops of Ph.Ph + 1

ml of unknown

 

 

Pink color disappears on cold

  • Ve and returned by heating

Go to the sixth step unknown is Glycerol

 

 

Sixth:

In dry test tube put 1ml of unknown + 0.5gm of salicylic acid + 2drop of conc. H2SO 4 and heated in water bath for 3 min. then pour the content into beaker containing Na 2CO3 solution.

Vix smell appear ( Methyl salicylate ) unknown is methanol .

 

Neutral Solution N.S.:

Add to the acid aqueous NH3 ( NH4OH) till the solution is just alkaline to litmus Boil the solution until the evolution of NH3 gas ceases ( this can be ensured by exposing a red litmus paper to vapor) .

****************************

 

Experiment to differentiate between formic and acetic acid :

 

 

Test

 

Formic acid

 

Acetic acid

 

1-Mercury chloride test: 1ml of N.S. of acid +1ml of HgCl2 & added excess then boil .

 

White ppt. immediately appear & change to gray ppt. with boiling .

 

White ppt. change to yellow ppt. with boiling .

 

2-Permanganate test: 1ml of warm acid + drops of KMnO4 .

 

The color disappear.

 

The color will not disappear.

Experiment to differentiate between formaldehyde and Acetaldehyde :

 

 

Test

 

Formaldehyde

 

Acetaldehyde

 

1-Resorcinol test:

In a test tube put 1ml of HCHO

+ drops of resorcinol +1ml of H2SO4 conc. added down the side of the test tube.

 

Red violet ring is formed at the interface

(A white ppt. appears over the ring ) .

 

 

– Ve

 

 

2- nitroprusside sodium test: In the test tube put 1ml of aldehyde + 0.5 ml of Sodium nitroprusside then put drops of NaOH with shaking .

 

 

– Ve

 

 

Dark red color .

 

***************************************

 

 

 

 

AROMATIC ORGANIC ACIDS

 

 

1-Benzoic acid C6H5COOH

Benzoic acid is a white crystalline solid undergo sublimation by heating partially soluble in cold water, freely soluble in hot water and ethanol m.p. is 121 °C .

 

Test

 

Observation

 

Result

1-Acidity test :

0.25gm of acid +1ml of conc.

NaHCO3 solution .

 

CO2 evolves with effervescence

 

The compound from carboxylic acid.

2-Ferric chloride test :

1ml of N.S. + drops of FeCl3 .

buff ppt.

The ppt. is basic ferric benzoate (33) .

COONH4 COO)Fe(OH)2

word image 793

 

+ FeCl3+ NH4Cl

…(33)

3-Estrification test :

0.25gm of acid +1ml of ethanol +1ml of conc. H2SO4 & heat in water bath 3 min. then pour into beaker contain NaHCO3 solution .

 

Specific odor

 

The odor due to Ethyl benzoate (34) .

 

COOH COOC2H5

word image 794

H

2

SO

4

conc

 

+ C2H5OH+ H2O

 

Ethyl benzoate …(34)

 

2-Salicylic acid C6H5(OH)COOH

 

Salicylic acid is a white crystalline solid undergo sublimation by heating, partially soluble in cold water, freely soluble in hot water and ethanol m.p. is 159 °C .

 

Test

 

Observation

 

Result

1-Acidty test :

0.25gm of acid +1ml of conc.

NaHCO3 solution.

 

CO2 evolves with effervescence

 

The compound from carboxylic acid

2-Ferric chloride test :

1ml of N.S. + drops of FeCl3 .

 

Violet color

Specific test of salicylic acid

3-Estrification test :

0.25gm of acid +1ml of methanol +1ml of conc. H2SO4 & heat in water bath 3 min. then pour into beaker contain Na2CO3 solution

 

Vix odor

 

The odor due to Methyl salicylate ester (35) .

 

COOHCOOCH3

word image 795word image 796

H

2

SO

4

conc

 

+

+

OHOH H2O

Methyl salicylat …(35)

 

DI CARBOXYLIC ACID

 

 

1-Oxalic acid COOH

COOH

 

Oxalic acid is a colorless crystalline solid freely soluble in water and alcohol, it undergo pyrolysis without charring up on heating .

 

Test

 

Observation

 

Result

1-Acidity test :

0.25gm of acid +1ml of NaHCO3 solution .

 

CO2 evolves with effervescence

 

The compound from carboxylic acid.

2-Ferric chloride test :

1ml of N.S. + drops of FeCl3 .

 

No change for FeCl3 color

 

Oxalic or tartaric or citric

acid.

3-Calcium chloride test :

1ml of N.S. of acid +1ml of CaCl2

 

White ppt. on cold

 

The ppt. is calcium oxalate specific test for oxalic acid

4-Silver nitrate test:

1ml of N.S. of acids +2ml of silver nitrate AgNO3 .

 

White ppt. dissolve in ammonia and

HNO3 acid

 

The ppt. is silver oxalate.

5- potassium Permanganate test:

1ml of warm acid + drops of

KMnO4 .

 

The color of

KMnO4 disappear

 

Oxidation for oxalic acid.

HO CH COOH

2-Tartaric acid

HO CH COOH

 

Colorless crystalline solid, freely soluble in water and alcohols. Heating of acid or its salts, they undergo charring with evolution of burned sugar odor.

 

 

Test

 

Observation

 

Result

1-Acidity test:

0.25gm of acid +1ml of NaHCO3

CO2 evolves with effervescence

The compound from carboxylic acid

2-Ferric chloride test:

1ml of N.S. of acid + drops of FeCl3

No change for FeCl3

color

Oxalic or tartaric or citric acid

3-Calcium chloride test:

1ml of N.S. of acid +1ml of CaCl2

White ppt. appear after scratching the inner wall

of the tube

The ppt. is calcium tartarate specific test for tartaric acid

4-Silver nitrate test:

1ml of N.S. of acids + 2ml of silver nitrate AgNO3 .

 

White ppt. soluble in excess of N.S.

 

The ppt. is silver tartarate

5- potassium Permanganate test :

1ml of warm acid + drops of KMnO4

The color of KMnO4 disappear on heating

Oxidation of

Tartaric acid

6-Fenton’s test:

1ml of acid + 1drop of dilute solution of FeSO4 then 1drop of 10% H2O2 .

Green color turns into intense violet color on adding excess NaOH

solution.

 

specific test for tartaric acid

7-Potassium dichromate test :

1ml of acid +1ml K2Cr2O7 & heat

The color change to

green .

specific test for tartaric acid

COOH

3-Citric acid COOH

CH

2

C

CH

2

H

O

COOH

Citric acid is Colorless crystalline solid, freely soluble in water and alcohols. By heating a heavy vapor with irritating smell evolved and finally undergo charring

 

Test

 

Observation

 

Result

1-Acidity test :

0.25gm of acid +1ml of NaHCO3 solution .

 

CO2 evolves with effervescence

 

The compound from carboxylic acid

2-Ferric chloride test:

1ml of N.S. + drops of FeCl3.

 

No change for FeCl3

color

 

Oxalic or tartaric or citric acid

3-Calcium chloride test : 1ml of N.S. of acid +1ml of

CaCl2.

 

White ppt. appear after boiling

 

The ppt. is calcium citrate specific test of citric acid

4-Silver nitrate test :

1ml of N.S. of acids + 2ml of silver nitrate AgNO3 .

 

White ppt. dissolve in ammonia

 

The ppt. is silver citrate

5-Denig’s test :

2ml of N.S. + 2ml of denig’s A & heating until boiling then add 2 drops of deng’s B .

Color of permanganate will

disappear and heavy white ppt. formed

 

specific test of citric acid

 

 

PHENOL

 

Phenol is aromatic compound contains one or more hydroxyl group (OH) connected directly to aromatic nucleus.

Phenol classified according to the number of hydroxyl contained group into :

word image 797 Monohydric phenol

Dihydric phenol Trihydric phenol

 

General properties of phenol:

 

  1. Solubility:

Phenol soluble in sodium hydroxide solution (NaOH) or potassium hydroxide (KOH) ,phenol differ from acids it doesn’t dissolve in basic carbonate like sodium carbonate Na2CO3 and potassium carbonate k2CO3.

 

  1. Ferric chloride test:

This test used to identify phenols it gives complex with red, blue, Purple or green color.

 

  1. Azodye formation test:

Diazonum salt react with phenols in basic medium via substitution forming compounds, known as AZODYE, most of them used in cloth dying. Azodyes are colored and they color depend on the kind of phenol and the aromatic amine which used to form the azo compound.

 

  1. Bromination test:

Phenols react with bromine forming the substituted product which are mainly solids.

OH

1-Phenol

Phenol is a colorless crystals in pure state, which turned to light red when exposed to air it has characteristic odor. Soluble in water, alcohols, ethers, and sodium hydroxide. Highly toxic .

 

Test

 

Observation

 

Result

1-Ferric chloride test:

Diluted solution of phenol in alcohol thenadd

2 drop of FeCl3 .

 

Violet color appear

 

The compound from phenols

2-Azo dye formation test:

Take 3 test tube

Tube (1): 1ml of aniline +3.5ml of conc. HCl

Tube (2): 1ml of sodium nitrite NaNO2

Tube (3): phenol dissolved in excess NaOH.

Keep the 3 test tubes in ice bath& Put tube

(2) (1) slowly, then add mixture to tube (3).

 

 

Red dye

 

 

Dye is Benzene azo phenol (36)

 

NaNO

2

HCl

N

NCl

NH

2

Aniline Dyazonium salt

+

N

NCl

OH

N

N

Dyazonium salt Phenol Benzene azo phenol

 

OH

…….(36)

word image 798

OH 2-Resorcinol

OH

 

Resorcinol is solid ,dissolve in water and alcohol but in soluble in benzene.

 

 

Test

 

Observation

 

Result

1-Ferric chloride test:

Diluted solution of resorcinol in alcohol then add 2 drop of FeCl3 .

 

Deep violet color appear

 

The compound from phenols

2-Azo dye formation test:

Take 3 test tube

Tube (1): 1ml of aniline + 3.5ml of conc. HCl

Tube (2): 1ml of sodium nitrite NaNO2

Tube (3): resorcinol dissolved in excess NaOH.

Keep the 3 test tube in ice bath & Put tube

(2) (1) slowly, then add mixture to tube (3).

 

Red dye

 

The dye is

Benzene azo resorcinol

3-Chloroform test :

1ml of resorcinol dissolved in excess 20% NaOH

+1ml of chloroform CHCl3 then heat in water bath

 

Red fluorescent

 

Compound is

resorcinol

4-Phethalen test:

In dry test tube add 0.5gm of resorcinol + 0.5 gm of phthalic anhydride +2drop of conc.H2SO4 , and gently fuse together allow to cool , and then add 30% NaOH solution in excess

 

Red fluorescent in the inner &

Green fluorescent in the wall.

 

Compound is

resorcinol

 

 

72

OH

3-α-Naphthol

 

Solid, insoluble in water, alcohol, ether and sod.hydroxide solution.

 

Test

Observation

Result

1-Ferric chloride test:

Diluted solution of α-naphthol in alcohol thenadd

2 drop of FeCl3 .

 

Greenish color turns to violet

 

The compound from phenols

2-Azodye formation test:

Take 3 test tube

Tube (1): 1ml of aniline +3.5ml of conc. HCl

Tube (2): 1ml of sodium nitrite NaNO2

Tube (3): α-naphthol dissolved in excess NaOH. Keep the 3 test tube in ice bath& Put tube (2) (1) slowly, then add mixture to tube (3) .

 

 

Brownish red

ppt.

 

 

Dye is

Benzene azo α-naphthol

3-Chloroform test :

1ml of α-naphthol dissolved in excess 20% NaOH

+1ml of chloroform CHCl3 then heat in water bath

 

Blue color turns to green

 

Compound is

α-naphthol

 

4-Phethalein test:

In dry test tube add 0.5gm of α-naphthol + 0.5 gm of phthalic anhydride +2drop of conc.H2SO4, and gently fuse together allow to cool , and then add 30% NaOH solution in excess .

 

 

Green Color

 

Compound is

α-naphthol

 

4-β-Naphthol OH

 

Test

 

Observation

 

Result

1-Ferric chloride test:

Diluted solution of β-naphthol in alcohol then add 2 drop of FeCl3 .

 

Greenish color turns to violet

 

The compound from phenols

2-Azo dye formation test:

Take 3 test tube

Tube (1): 1ml of aniline +3.5ml of conc. HCl

Tube (2): 1ml of sodium nitrite NaNO2

Tube (3): β-naphthol dissolved in excess NaOH.

Keep the 3 test tube in ice bath & Put tube

(2) (1) slowly, then add mixture to tube (3) .

 

 

 

 

orange dye

 

 

Dye is Benzene azo β-naphthol

3-Chloroform test :

1ml of β-naphthol dissolved in excess 20% NaOH +1ml of chloroform CHCl3 then heat in water bath.

 

Blue color turns to green .

 

Compound is β-naphthol

4-Phethalen test:

In dry test tube add 0.5gm of β-naphthol + 0.5 gm of phthalic anhydride +2drop of conc.H2SO4 , and gently fuse together allow to cool , and then add 30% NaOH solution in exces

 

Green Color

 

Compound is β-naphthol

 

Scheme for solid sample

word image 3096

 

Organic compound

 

Solid compound:

 

  1. Acids:

Benzoic acid – Salicylic acid – Oxalic acid -Tartaric acid – Citric acid.

 

  1. Sodium salt for acid:

Sodium acetate – Sodium format – Sodium Benzoate – Sodium Salicylate Sodium Oxalate -Sodium Tartarate – Sodium Citrate.

 

  1. Ammonium salt for acid:

Ammonium acetate – Ammonium format – Ammonium Citrate Ammonium Salicylate – Ammonium Oxalate – Ammonium Tartarate.

 

  1. Aniline salts:

1-Aniline Hydrochloride 2- Aniline Sulfides

 

NH2.HCl NH2.H2SO4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

odo

r of ammonia

 

we have ammonium salt of acid

 

Red colo

r change

 

to brown ppt. with

heating unknown is

ammonium format or

ammonium acetate

 

Puff

ppt.

 

unknown is

ammonium Benzoate

 

Violet colo

r

 

unknown is

ammonium salicylate

 

V

e

unknown is

ammonium oxalate

or tartarate

 

or citrate

 

 

 

White ppt. after scratching the

inner wall of the tube

 

unknown is ammonium tartarate

 

White ppt.

on cold

 

unknown is

 

ammonium oxalate

 

White ppt. after boiling

 

unknown is ammonium

citrate

 

No odo

r of ammonia

 

there is no ammonium salt

 

Go to second step

 

ml of

1

N.S.

 

of salt

 

+

 

drops of

FeCl

3

 

1

ml of

N.S. of salt

+

1

ml of CaCl

2

 

First:

 

0.25

gm of unknown +

 

ml

1

 

of

NaOH

 

Second: 0.25 gm of unknown + 1ml of Na

2

CO

3

solution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

No evolution

 

we have sodium salt for acid

 

CO

2

 

evolves with effervescence

 

unknown is carboxylic acid or

aniline salts

 

 

Go to the Third step

 

 

Red c

olo

r change to

brown ppt. with

heating unknown is

sodium format or

sodium acetate

 

Puff

 

ppt.

 

unknown is sodium

Benzoate

 

 

Violet colo

r

 

unknown is

sodium salicylate

 

 

unknown is

 

V

e

 

sodium oxalate or

tartarate or citrate

 

White ppt. on cold

 

unknown is

 

sodium oxalate

 

 

White ppt. after scratching

the inner wall of the tube

 

unknown is sodium tartarate

 

 

White ppt. after heating

 

unknown is sodium

citrate

 

ml of

1

N.S.

 

of salt

 

+

 

drops of

FeCl

3

 

ml of

1

N.S. of salt

+

ml of CaCl

1

2

 

 

Third:

 

test of dye formation

Take 3 test tube

Tube (1): 1ml of aniline

 

+

of conc. HCl

3.5

Tube (2): 1ml of sodium nitrite NaNO

2

 

 

Tube (3): β-naphthol dissolved in NaOH.

Then Put 3 test tube in ice bath & Put tube (2)

 

(1) slowly, then add

mixture on tube (3)

 

 

 

 

 

 

Forth: 1ml of N.S. of acid + drops of FeCl

3

 

 

 

 

 

 

 

 

 

 

 

Red dye formed unknown

is aniline hydrochloride or

 

aniline sulfides

 

No dye formed

 

Go to the fourth step

Buff

ppt.

 

unknown

 

is Benzoic acid

 

 

Violet

 

colo

r

unknown

 

is salicylic acid

 

 

ve

unknown is

o

xalic

or tartaric or citric acid

 

White ppt. on cold

 

unknown is Oxalic acid

 

 

White ppt. after scratching

the inner wall of the tube

 

unknown is Tartaric acid

 

White ppt.

 

after boiling

 

unknown is citric acid

 

 

ml of N.S. of acid

1

+

 

1

ml of CaCl

2

 

Confirmatory test:

Test

Formic acid or its salt

Acetic acid or its salt

1-Mercuric chloride test:

1ml of N.S. of unknown +1ml of HgCl2 and boil.

White ppt. immediately change to gray with

boiling

White ppt. change to yellow by

boiling

2-Permanganate test:

1ml of warm acid

+ drops of KMnO4 .

 

The color will disappear

 

The color will not disappear

 

 

Test

 

Hydrochloride Aniline

 

Sulfides Aniline

 

Unknown +AgNO3.

 

white ppt. from silver

chloride

 

-ve

 

Unknown+BaCl2 .

 

-ve

white ppt. from silver

sulphate

 

word image 799 Notes:

Preparation of N.S. for ammonium and sodium salt :

By dissolve the salt in water only .

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