Physical and Chemical Properties of Amines and Amides Questions

 

Experiment #7: Amines and Amides

 

Objective:

 

Physical and chemical properties of amines and amides will be observed. Solubility, odor will be the physical properties observed. Chemical properties of amines will be observed by their basicity. Chemical property of amides will be observed by hydrolysis reaction when converting to carboxylic acids and amines or ammonia.

 

Background

 

Amines and Amides are organic compounds containing nitrogen. The polarity of amines and amides decreases as the number of hydrogen atoms attached to the nitrogen decreases. Many amines have characteristically fishy odors.

 

Amines are considered weak bases due to the unshared pair of electrons which can attract a proton from a water molecule. Because amines are bases, they can react with acids to form amine salts. These salts often are much more soluble then the original amine.

 

Amides are the nitrogen derivatives of carboxylic acids, having a carbonyl carbon attached to the amine group. Amides are formed by the reaction of a carboxylic acid with ammonia or an amine.

 

Amides, like esters, maybe hydrolyzed in either acids or bases conditions.

 

 

 

Safety Precautions

Wear safety glasses at all times when in the laboratory.

Acids and bases are corrosive. If you come in contact with an acid or base, wash the affected area with water for a minimum of 15 minutes followed by a wash with soap and water.

Use boiling chips for water bath. Dispose of chips as directed by instructor.

Use beaker tongs or hot mitts to handle hot beakers.

Dispose of solution and mixtures as directed by your instructor

 

Experimental Procedure

 

In preparation for a later procedure, set up a hot water bath by placing a 400 mL beaker containing approximately 200 mL of DI water and a couple boiling chips on a hot plate. The temperature of the water should reach 95 – 100°C.

 

Solubility and pH

 

  1. Note and record the physical state of each of the following substances: triethylamine, N-methylaniline, acetamide and benzamide. Note the odor of each substance by removing the bottle lid and carefully wafting the odor toward you. Record your observations.

 

  1. To different small test tubes add 5 – 10 drops (for liquids) or about 0.2 g (for solids) of triethylamine, Nmethylaniline, acetamide and benzamide. Add 2 mL of DI water to each of these test tubes. Vortex and record your observations.

 

  1. Test the contents of each test tube with pH paper. Dip a stirring rod to the test tube and moist it on a piece of pH paper. Record the pH observed by comparing it to the pH chart. Make sure to clean stirring rod between test tubes. As a control, also test the pH of DI water.

 

  1. Save the test tubes containing N-methylaniline and benzamide for the next steps. Dispose contents of remainder test tubes as directed by your instructor.

 

Reactions with HCl and NaOH

 

  1. To the test tube containing N-methylaniline, add 10 drops of 6 M HCl. Vortex. After vortexing, stopper the test tube using a rubber stopper and invert it gently several times so that the acid contacts the entire contents of the test tube. Record your observations. Note the odor and record your observations. Next add 1 mL (20 drops) of 6 M NaOH. Vortex and record your observations. Note the odor and record your observations. Dispose of contents in test tube as directed by your instructor.

 

  1. To the test tube containing benzamide, add 1 mL (20 drops) of 6 M NaOH. Vortex. Place the test tube in the hot water bath. (Note: water’s temperature should be 95 – 100°C). Moisten a strip of pH paper and place it over the mouth of the test tube after 5 minutes in water bath. Record the pH observed. After 20 minutes remove test tube from water bath. Note the appearance of the contents in test tube. Record your observations. Place test tube in a beaker of cold water to cool it rapidly to room temperature. Record your observations. To the cooled mixture, add 2 mL of 6 M HCl. Mix it and record your observations. Dispose of reaction as directed by your instructor.

54 Cuyamaca College

Name____________________________

Section____________________________

Experiment #7 – Data and Observations

Substance

Physical State

Odor

Addition of water

pH

Triethylamine

clear/colorless liquid

Fishy

clear, colorless soution

12

N-methylaniline

clear/yellow liquid

Faint fishy

2 layers yellow on top layer

and colorless on bottom

7

Acetamide

white solid

Faint pungent

clear, colorless solution

6

Benzamide

white solid

none

white solid dispersed in water, did not dissolve

 

6

Water

   

6

Substance

Addition of HCl

Odor

Additional of

NaOH

Odor

N-methylaniline

clear, yellow solution

Fainty fishy

cloudy at first, yellow layer

on top after mixing

Faint fishy

Substance

pH above

test tube

 

Appearan

ce

In hot water

In cool mixture

After HCl addition

Benzamide

11

Clear, colorless solution

Clear and colorless solution

white solid forms

 

Post-Laboratory Questions

 

  1. Which substances were solids? What class of organic compound are they? Why are these substances solids?

 

 

 

 

 

  1. Which substances had a distinctive odor? What class of organic compounds are they?

 

 

 

 

  1. a. Which substances were soluble in water?

 

 

 

    1. Which substances were insoluble in water?

 

 

 

    1. Explain why some substances were soluble and some were insoluble in water.

 

 

 

  1. a. Based on its observed pH, what type of substance is triethylamine?

 

 

 

    1. Would the pH of a sodium hydroxide solution be the same, higher or lower than that of triethylamine? Give your reasoning.

 

 

 

 

  1. Give the IUPAC name write the structure of:

 

    1. Triethylamine

 

 

 

 

    1. acetamide

 

 

 

 

 

56 Cuyamaca College

 

  1. a. Write the chemical equation that explains the observations on addition of HCl to the mixture of N methylaniline and water.

 

 

 

 

 

 

 

 

    1. Write the chemical equation that explains the observations on the addition of NaOH to the mixture of N-methylaniline, water and HCl.

 

 

 

 

 

 

 

 

  1. a. Write the chemical equation that explains the observations on heating benzamide with NaOH.

 

 

 

 

 

 

 

 

 

    1. Write the chemical equation that explains the observations on the addition of HCl to the mixture of benzamide and NaOH after heating.

 

 

 

 

 

 

 

 

 

 

 

 

Order a unique copy of this paper
(550 words)

Approximate price: $22