Question

Give an example reaction that would yield the following products as major organic products. For oxidation reactions, just write oxidation over the arrow and don’t worry about the actual reagent.

a. primary alcohol e. ketone

b. secondary alcohol f. carboxylic acid

c. tertiary alcohol g. ester

d. aldehyde

Short answer

(a) To obtain a primary alcohol as major product we hydrated the ethane, described in the solution

(b)Prop-1-ene and water in acidic conditions yield propan-2-ol, which is a secondary alcohol.

(c) Addition of water to 2-methylprop-l-ene under acidic conditions gives 2-methylpropan-2-ol which is a tertiary alcohol.

(d) Oxidation of ethanol to acetaldehyde

(e) Oxidation of propan-2-ol to propan-2-one.

(f) Oxidation of ethanol to acetic acid.

(e) The reaction of ethanol and acetic acid under acidic conditions yields ethyl acetate

Step-by-step solution

To Give an example reaction Primary alcohol        

To obtain the primary alcohol alkene is hydrated. (ethene).

Ethene when reacting with${\text{H}}_{\text{2}}\text{O}$:

-"OH" separated from water molecule will attach to the first carbon atom,

-residual " H " will attach to the second carbon atom.

Therefore, the product will be ethanol.

Hence To obtain a primary alcohol as a major product ethane is hydrated which is , described in the solution.

To Give an example reaction Secondary alcohol   

Secondary alcohol can be obtained by addition of water to the alkene.

One carbon atom forming a double must be substituted and the other carbon atom must have two protons attached in order to yield secondary alcohol.

An example of such a reaction is the addition of water to prop-1-ene to give propan-2-ol.

Hence Prop-1-ene and water in acidic conditions yield propan-2-ol, which is a secondary alcohol.

Step 3:To Give an example reaction Tertiary  alcohol

An example of a reaction in which tertiary alcohol is formed is the addition of water to 2-methyl-prop-1-ene in an acidic medium. The product is 2-methylpropan-2-ol, which is a tertiary alcohol.

It is important that the alkene from which the reaction starts has one carbon atom which is double substituted to ultimately yield tertiary alcohol.

Hence Addition of water to 2-methylprop-l-ene under acidic conditions gives 2-methylpropan-2-ol which is a tertiary alcohol.

To Give an example reaction Aldehyde

Aldehydes can be obtained by selective oxidation of primary alcohols.

Choose oxidizing reagents wisely as the most used oxidizing reagents are too strong and cause the oxidation of alcohol to carboxylic acids.

Hence Oxidation of ethanol to acetaldehyde

To Give an example reaction ketone

Ketones can be obtained by oxidation of secondary alcohols.

There is a wide range of oxidation reagents that can be used to oxidize secondary alcohols to ketones.

An example of such oxidation is shown below.

Hence Oxidation of propan-2-ol to propan-2-one.

To Give an example reaction Carboxylic acid

Carboxylic acids can be obtained by oxidation of primary alcohols.

Reagents such as potassium dichromate or potassium permanganate are most commonly used for this purpose.

The figure below shows the oxidation reaction of ethanol to acetic acid.

Hence Oxidation of ethanol to acetic acid.

Step 7:To Give an example reaction ester

The most common ester preparation reaction is Fisher esterification.

Fisher esterification is a reaction between an alcohol and a carboxylic acid in an acidic medium whereby the hydroxyl group is substituted with an alkoxy group, and ultimately an ester is formed.

The figure below shows the reaction of ethanol and acetic acid under acidic conditions, and the product is ethyl acetate.

Hence The reaction of ethanol and acetic acid under acidic conditions yields ethyl acetate