7.9.1      AMINES

QUESTIONS

Section A

 

For each of the questions only one of the lettered responses (A – D) is correct.

 

Select the correct response in each case and mark its code letter by connecting the dots as illustrated on the answer sheet.

 

1               Which one of the following substances will decompose to give a gas on gentle warming?

 

A                CH3NH2

       +

$B    NºNCl-

      |

 

 

C    CH3CH2CºN

D    NO2

      |

 

 

 

2               Which one of the following is true about methylamine?

 

A  It is a weaker base than ammonia.

B  It is a weaker base than phenylamine.

C  It is insoluble in water but soluble in dilute acid

          $D  It can be prepared by reduction of ethanenitrile using LiAlH4.

 

3         
Section B

 

1.         Putrescine is a diamine formed by the putrefaction  (rotting) of the proteins in flesh.

NH2CH2CH2CH2NH2

      Putrescine

 

It is a poisonous solid, m.pt. 27 oC, with an unpleasant odour, and is soluble in water, forming an alkaline solution.

 

(a)                Give a simple definition of a protein illustrating your answer with a repeating part of the protein structure.

 

 

 

 

                                                                                                                                   

 

                                                                                                                                   

                                                                                                                                    [3]

(b)               Suggest a systematic name for putrescine.

 

                                                                                                                                   

[1]

(c) (i)   Suggest an explanation why putrescine is soluble in water.

 

                                                                                                                                   

 

                                                                                                                                   

 

                                                                                                                                   

 

                                                                                                                                   

                                                                                                                                    [2]

 

(ii)               Write a balanced equation for the reaction of excess hydrochloric acid with putrescine to form a salt.

 

                                                                                                                                   

[1]

(iii)             Explain how it is possible to liberate putrescine from the salt formed with hydrochloric acid.

 

                                                                                                                                   

 

                                                                                                                                   

 

                                                                                                                                   

 

                                                                                                                                   

                                                                                                                                    [1]

(d)               Putrescine may be synthesised by the following flow scheme:

 

CH2COOH         A          CH2COO-NH4+          heat            CH2CONH2

½                                  ½                                              ½

CH2COOH                     CH2COO-NH4+                           CH2CONH2

                                                                                               

                                                                                            B

                                                                                                           

CH2CH2NH2                  C          CH2CN

½                                              ½

CH2CH2NH2                              CH2CN

 

Name the reagents A-C.

 

     A                                                                                                                

 

     B                                                                                                                

 

     C                                                                                                                

                                                                                                                                    [3]

(e)               The reactions of putrescine are typical of those of a primary amine.  Write the

formulae for the organic products formed in the reactions of putrescine with excess nitrous acid and excess ethanoyl chloride.

(i)                 nitrous acid

 

CH2CH2NH2     excess HNO2

½

CH2CH2NH2

 

(ii)               ethanoyl chloride

 

CH2CH2NH2     excess CH3COCl

½

CH2CH2NH2

                                                                                                                        [2]

 

(f)               Putrescine can act as a bidentate ligand forming a complex with the nickel (II) ion.

(i)                 What structural feature does putrescine possess that allows it to act as a ligand?

 

                                                                                                                                   

 

                                                                                                                                   

[1]

 

(ii)               Draw possible structure for the complex formed between putrescine and nickel ions.

 

 

 

 

 

 

 

 

 

 

 

 

                                                                                                                                    [2]

                                                                                                            NI98S