Properties of primary amines

Question 1

Why does ammonia now have a bonding angle of a perfect tetrahedrom? 109.5°

What is the angle?

Answer 1

Prescence of lone pair repels more than the bonding electrons in the N-H bond

amines keep this basic shape

Question 2

What bonding occurs in a primary amine?

Answer 2

can hydrogen bond to one another using their -NH2 group

Question 3

How does the bonding in amines compare to alcohols

Answer 3

they are not as a strong as the hydrogen bonds formed with an -OH groupbecause nitrogen is less electronegative than oxygen

therefore they have lower boiuling points

Question 4

What are the properties of amine chain with increasing chain lengths?

Answer 4

shorter chain amines such as methylamine and ethylamine are gases at room temperature

slightly longer chain are volatile liquids

Question 5

Are primary amines soluble?

Answer 5

primary amines with chain lengths up to about four carbon atoms are very soluble in both water and in alcohols

this is because they form hydrogen bonds with these solvents

most amines are soluble in less polar solvents

Question 6

Why is phenylamine not very soluble in water?

Answer 6

benzene ring cannot form hydrogen bonds

Question 7

How can amines react?>

Answer 7

the lone pair may be used to form a bond with:

• a H+ ion, when the amine is acting as a base
  
  • an electron-deficient carbon atom, when the amine is acting as a nucleophile