Question

Which of the following molecules contain a good leaving group? он Cн,CH,NHz она CH3CH2CH2 CH2CH2CH2CH2CI

Answer 1

Answer ) there are 3 molecules that contain good leaving group.

1) is protonated alcohol in protonated cyclohexanol

2) iodide in Iodopropane

3) chloride in Chlorobutane

A good leaving group is a weak base

OH, 2) CH₂CH₂CH₂ I Protonated Iodide ion Alcohol 3 CH ₂ CH₂ CH₂ CH₂ ce chloride in

1)Protonated alcohol is a leaving group because any nucleophile can attack on C-O bond and the carbon oxygen Bond will break and water will be removed therefore it is a good leaving group.

2)&3) both iodide and chloride are weak bases because they have 7 Valence Electrons and they want to accept one more electron to complete their octet rather than acting as a base but between these two iodide is a better leaving group than chloride ion because it has a bigger size thus makes a longer Bond with carbon which is weaker and the carbon - iodide bond easily breaks and iodide thus acts as a better leaving group than chloride .

Reasons for others molecules not being good leaving group:

1)Amines are most basic class of organic compounds and thefirst molecule given is ethyl amine ( CH3CH2NH2 )

So it is not a good leaving group

2)Cyclohexane is given it contains only hydrocarbon Chain and doesn't contain any leaving group . Hydrocarbon chain is bonded with covalent bond which is a very strong bond therefore no bond is broken as there is no leaving group present.

3) cyclohexanol is given and in alcohols hydroxyl Ion being strong base is a poor leaving group .