Alcohols revisited (and ethers)
and going further .
13.3 Carboxylic acids and their derivatives
homologous series containing the OH hydroxyl group.
all names end in ol eg methanol, ethanol etc.
isomers are possible for alcohols containing 3 or more carbons.
label position of OH group so that it has the lowest number possible.
polyhydric alcohols contain more than one OH group eg propane- 1,2,3,triol
OH groups attached to benzene rings are called phenols.
Molecules are polar, in the O-H bond, O is - and H is +
Molecules have attractive forces between the molecules called hydrogen bonds, not as strong as covalent bonds.
Higher boiling point than corresponding alkanes.
Hydrogen bonds form between alcohol and water molecules therefore they are miscible / soluble.
Long chain alcohols are less soluble.
General formula R-O-R’
O-R’ alkoxy group substituted for H eg
Longer hydrocarbon chain is parent alkane for naming.
Molecules only slightly polar.
No hydrogen on the oxygen atoms to form hydrogen bonds – only weak forces of attraction between molecules.
Boiling points similar to corresponding alkane.
Lower ethers, very volatile, highly flammable.
Only slightly soluble in water, mix well with other non-polar solvents eg alkanes. (Like dissolves like).
Oxygen atoms not joined together.
General formula when rest of structure is an alkyl group R-COOH.
CH3 -CH3 ethane
H-COOH methanoic acid
CH3 -COOH ethanoic acid
CH3-CH2-COOH propanoic acid
CH3-CH(CH3)-CH2-COOH 3-methylbutanoic acid
Two carboxylic acid groups -dioic
Carboxyl group can be attached to a benzene ring eg benzenecarboxylic acid.
benzenecarboxylic acid (benzoic acid)