Alcohol & Phenol Reactions

Alcohol Reactions

• 1. Dehydration - elimination of water

• water is eliminated from adjacent carbon atoms and a second bond is formed between the 2 carbon atoms

• uses a large amount of alcohol and a small amount of acid (H



• order of reactivity:


) as the catalyst

– tertiary > secondary > primary

Dehydration Examples

1. Dehydrate butanol.

2. Dehydrate 2-butanol.

3. Dehydrate 2-methyl-2-butanol.

• 2. Halide Substitution alcohols react with concentrated hydrohalogens (HCl, HBr, HF) to be converted into alkyl halides

• competes with the elimination reaction

(dehydration) but this reaction is favored using a large excess of concentrated acid

(HCl and zinc chloride)

• we can distinguish between 1 ° , 2 ° and 3°

• order of reactivity:

– tertiary > secondary > primary alcohols by their different rates of reaction using the Lucas Test

Halide Substitution Examples: The Lucas Test

• 1. Primary alcohols - are not converted to alkyl chlorides at room temp; dissolve completely

• 2. Secondary alcohols – dissolves, but within 5 minutes, the alkyl chloride separates out

• 3. Tertiary alcohols – react immediately; the insoluble tertiary alkyl chloride separates out as a cloudy layer

• 3. Esterification – alcohols react with carboxylic acids to form esters and water

• esters – compounds in which the proton of an acid is replaced by an organic group

• General formula is

• Esters are named as derivatives of BOTH the carboxylic acid and the alcohol

– The 1 st word denotes the alcohol group (R) and is named like a hydrocarbon with a –yl ending

– The 2 nd word is derived from the name of the parent acid, with the “-ic acid” ending changed to an “-ate” ending.

Esterification Examples

• Ex.1 React methanol with acetic acid.

• Ex.2 React propanol with butanoic acid.

• Ex.3 React 2-propanol with butanoic acid.

• 4. Oxidation - the most important method of preparing aldehydes, ketones and carboxylic acids from alcohols

aldehyde ketone carboxylic acid

• Uses Jones Reagent in what is called the

Bordwell-Wellman Test

Jones Reagent water with H


– made by dissolving CrO



to give chromic acid, which is orange in color



Oxidation Examples

• Primary alcohols - oxidized in a 2-step process to first give an aldehyde, and then an acid

• Ex.; Oxidize ethanol.

• Secondary alcohols - oxidized to form ketones

• Ex.; Oxidize 2-butanol.

• Tertiary alcohols - have no C-H bonds on the hydroxyl carbon, therefore they cannot undergo oxidation.

• Ex.; Oxidize tert-butanol.

Reactions of Phenols

• Phenols DO NOT undergo dehydration or substitution reactions because it is very hard to break the C-O bond when the carbon atom is part of an aromatic ring

• They will form esters because the O-H bond is breaking, not the C-O bond

• 1. Esterification - phenol reacts with an acid anhydride (two acid molecules with a water removed) to form a carboxylic acid and an ester

• Ex.; part a : form acetic anhydride part b : react phenol with acetic anhydride

• 2. Oxidative Coupling - uses potassium ferricyanide, K




, as the catalyst

• -three types of coupling: ortho-ortho, ortho-para, and para-para

• Ex. React phenol with K




• Ex. React p-methylphenol with K