McMurry (Kap. 7,1) - Calculating the degree of unsaturation

Question 1

An alkene has 2 fewer hydrogens than an alkane (because of its double bond) - with same number of carbons.

What is the structural formula used for an alkane and alkene with same number of carbons?

Answer 1

Alkene: CnH2n (unsaturated)

Alkane: CnH2n+2

n = number of carbons.

Question 2

ring = loss of 2 Hydrogens

double bond = loss of 2 Hydrogens.

triple bond = loss of 4 Hydrogens

What is the degree of unsaturation?

Answer 2

The number of rings and/ or multiple bonds present in the molecule.

Question 3

How to measure the degree of saturation for molecules containing elements other then just carbon and hydrogens?

Answer 3

1) organohalogen compounds (C,H,X (X=F,Cl,Br or I).

One halogen acts as a replacement for hydrogen, therefore the presence of one corresponds to the removal of one hydrogen.

2) Organooxygen compounds (C,H,O)

Can be ignored, does not affect the degree of unsaturation.

3) Organonitrogen compounds (C,H,N)

One nitrogen binds one more hydrogen to itself, so the removal of one N, removes 1 H with it.