Chapter 26 Compounds with the carbonyl group

what is the carbonyl group

C=O bond

what is the iupac name of this

benzenecarbaldehyde

how do the boiling points of carbonyl compounds compare with alkanes and alcohols of similar chain length

C=O bond is strongly polar so dipole dipole forces can form

carbonyl compounds have higher boiling points than similar length alkanes but lower than alcohols because there is no hydrogen bonding

what is the solubility of carbonyl compounds

hydrogen bonds form between the O in C=O and water

solubility decreases as chain length increases

what forms when aldehydes are oxidised

carboxylic acid

why can’t ketones be oxidised

because a C - C bond has to be broken

what is the general equation for oxidation of aldehydes

RCHO + [O] → RCOOH

what happens when aldehydes and ketones are added to Fehling’s solution

Aldehyde reduces Cu2+ ions to Cu+ ions, forming a brick red precipitate of Cu₂O

Ketone shows no visible change

what happens when aldehydes and ketones are added to Tollen’s reagent

Aldehyde forms a silver mirror

Ketone shows no visible change

what is the reducing agent used to reduce aldehydes and ketones

NaBH₄

Tetrahydridoborate (III)

what is the general equation for reduction of aldehydes

what is the general equation for reduction of ketones

what is the symbol for a reducing agent

[H]

what are aldehydes and ketones reduced to

aldehydes → primary alcohols

ketones → secondary alcohols

what type of reactions are the reductions of aldehydes and ketones

nucleophillic addition

what is the mechanism for the reduction of an aldehyde

what is the mechanism for the reduction of a ketone

how are hydroxynitriles formed

add KCN followed by dilute acid to aldehydes or ketones

what is the general equation for the formation of a hydroxynitrile from an aldehyde

what is the general equation for the formation of a hydroxynitrile from a ketone

what type of reaction is the formation of hydroxynitriles from aldehydes and ketones

nucleophillic addition

what is the mechanism of aldehyde + KCN

what is the mechanism of ketone + KCN

what type of ketones can make a racemic mixture when reacted with KCN

unsymmetrical ketones

why can the addition of KCN to aldehydes and unsymmetrical ketones form a racemic mixture

the CN- ion can attack the partially positive C from the top or bottom

what are the dangers of using KCN

CN- ions are toxic

why can the H- nucleophile not reduce the C=C bond

H- is repelled by the high electron density in the C=C bond

why is KCN used instead of HCN to form hydroxynitriles

HCN is hard to store as a gas and can react to produce dangerous byproducts

what are the conditions for the reduction of aldehydes and ketones

aqueous conditions

uses of esters

food flavourings

perfumes

solvents

plasticisers

how is an ester made

carboxylic acid and alcohol react in presence of concentrated sulfuric acid catalyst

what is the solubility of carboxylic acids

up to and including butanoic acid are soluble

due to formation of hydrogen bonds

what type of molecules are vegetabl and animal oils

triglycerides

esters of propane-1,2,3-triol (glycerol)

what are the products when an ester is hydrolysed in acidic conditions

alcohol + carboxylic acid

what type of reaction is the hydrolysis of esters

nucleophillic addition

mechanism for hydrolysis of esters

what are the products when esters are hydrolysed in alkaline conditions

alcohol + salt of the carboxylic acid

how is soap made

hydrolise vegetable and animal oils in alkaline conditions

produces soap and glycerol

what are biodiesels

mixture of methyl esters of long chain carboxylic acids

e.g. CH₃OOC(CH₂)₁₄CH₃

how to produce biodiesels

vegetable oils reacted with methanol

in presence of a strong alkali catalyst

what vegetable oil is typically used to make biodiesel

rapeseed oil

structure of ethanoic anhydride

structure of ethanoyl chloride

structure of ethyl amine

order of reactivity of nucleophiles for acylation

1. primary amines

2. ammonia

3. alcohols

4. water

order of reactivity of acid derivatives

1. acyl chlorides

2. acid anhydrides

product formed when acyl chloride/acid anhydride reacts with ammonia

amide

product formed when acyl chloride/acid anhydride reacts with a primary amine

N-substituted amide

product formed when acyl chloride/acid anhydride reacts with a alcohol

ester

product formed when acyl chloride/acid anhydride reacts with a water molecule

carboxylic acid

what is the reaction of acyl chloride/acid anhydrides with nucleophiles

addition-elimination reaction

what is the advantage of using ethanoic anydride over ethanoyl chloride in the manufacture of aspirin

ethanoyl chloride produces HCl gas

but by product for ethanoic anhydride is ethanoic acid

name the molecule

ethanoic propanoic anhydride

name the molecule

propanamide

name the molecule

N-ethyl ethanamide

name the molecule

2-aminopropane