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. Never work alone in the lab.

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.
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.

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

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.

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

First aid in lab

Test Tube Racks

Test Tube

Test Tube Brushes

Test Tube Holder

Litmus Paper

Spatulas

Glass Stir Rod

Ring stands

Lab Equipment

Funnel

Dropper

Conical flask

Beaker

Buchner funnel

Watch Glass

Wash Bottle

Cylinder

Buchner flask

Mortar

&

pistil

Separating funnel

Beaker Tongs

Pipet

Bunsen Burner

clamp

Evaporating Dish

burette

Florence Flask

Rubber Stoppers

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.

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.

Gravity filtration:

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

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.

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.

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.

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 .

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:

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:

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.

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) .

Suggested experiments:

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

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

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.

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.

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. Cleaning 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. 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.

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 R_f Value:

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.

Suggested experiments:

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

Problems:

1- Calculate the R_f 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.

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 (78^oC). 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

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.

*********************************************** 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 C_nH_2n+2
• Example: Cyclohexane

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 C_nH_{2n .}
• Example: Cyclohexene

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)

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 C_nH_2n-2
• Example: Acetylenes HC CH

Preparation of Acetylene:

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

….. (5) …(5)

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:

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 .

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

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.

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

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1-Formaldehyde _H

H

C

O

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

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 .

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 .

O

4-Acetone CH _{3 C} CH₃

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

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 :

COOH HOCOOH

CH

CH

HCOOH CH3COOH ^COOH _HO COOH

formic acid

Acetic acid

oxalic acid Tartaric acid

Aromatic acid:

COOH

COOH

OH

Benzoic acid Salicylic acid

Neutral Solution of acid:

N.S of acid is the ammonium salt for acid

RCOOH + NH₄OH RCOONH₄ + H₂O

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

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

CaO/NaOH

heat

+ CO₂

COOH _OH

+ CO₂

OH

heat

CaO/NaOH

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

‘ H²SO^{4 ‘ ‘}

RCOOH + ROH RCOOR + H₂O

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.

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.

3-Lactic acid CH₃CH(OH)COOH

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

Scheme for liquid organics

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

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 :

Experiment to differentiate between formaldehyde and Acetaldehyde :

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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 .

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 .

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 .

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.

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

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 :

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 .

OH

3-α-Naphthol

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

4-β-Naphthol ^OH

Scheme for solid sample

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:

Notes:

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

By dissolve the salt in water only .