Chemistry, asked by ragiribhavyasre9228, 1 year ago

How to convert benzene into benzyl alcohol

Answers

Answered by siril
46

First, we will have to do Friedal crafts Alkylation to form Toluene.


Then, toluene is oxidized with KMnO₄ and then reduced with LiAlH₄ to get Benzyl alcohol.


The explanation is in the attachment below:


hope it helps!!

Attachments:

parinistha: after benzoic acid can we just add koH to it to form benzyl alcohol??
Answered by sadiaanam
0

Answer:

Benzyl alcohol is an organic compound in which a hydroxyl group is attached to a $ - {{C}}{{{H}}_2}$ group which is attached to the benzene ring. This cannot be done in one step. It involves several processes and formation of different compounds.

Explanation:

Benzyl alcohol is an organic compound in which a hydroxyl group is attached to a [Math Processing Error]

group which is attached to the benzene ring. This cannot be done in one step. It involves several processes and formation of different compounds.

Complete step by step answer:

The structures of benzene and benzyl alcohol are given below:

   

Benzene is a very stable organic compound. Thus it is very difficult for the direct substitution of the hydroxyl group. So it takes place in several steps:

First we have to do the Friedel-Crafts alkylation reaction of benzene. This is done by reacting the benzene with [Math Processing Error]

in the presence of aluminium chloride as catalyst. So the methyl group gets substituted in the benzene ring. The chemical reaction is given below:

Now this toluene is oxidized with potassium permanganate solution to give benzoic acid. The methyl group outside the benzene ring gets oxidized to form a carboxylic acid. This reaction must be in the basic medium followed by the addition of acidic hydrogen ions. We can use any oxidizing agents, but for oxidation of benzene, [Math Processing Error]

is used.

Now the benzoic acid has to be reduced to get benzyl alcohol. We have to use a suitable reducing agent like [Math Processing Error]

Thus benzene is converted to benzyl alcohol.

Note: There is another method for converting toluene to benzyl alcohol. Toluene is chlorinated first and then it is heated with aqueous sodium hydroxide or potassium hydroxide. When toluene is chlorinated, it forms benzyl chloride and then it forms benzyl alcohol when it reacts with sodium hydroxide or potassium hydroxide. The chemical reaction is given below:

Preparation. Benzyl alcohol is produced industrially from toluene via benzyl chloride, which is hydrolyzed: C6H5CH2Cl + H2O → C6H5CH2OH + HCl. Another route entails hydrogenation of benzaldehyde, a by-product of the oxidation of toluene to benzoic acid.

Benzyl alcohol (also known as α-Cresol) is an aromatic alcohol with the formula C6H5CH2OH. The benzyl group is often abbreviated "Bn" (not to be confused with "Bz" which is used for benzoyl), thus benzyl alcohol is denoted as BnOH. Benzyl alcohol is a colorless liquid with a mild pleasant aromatic odor. It is a useful solvent due to its polarity, low toxicity, and low vapor pressure. Benzyl alcohol has moderate solubility in water (4 g/100 mL) and is miscible in alcohols and diethyl ether. The anion produced by deprotonation of the alcohol group is known as benzylate or benzyloxide.

Natural occurrences

Benzyl alcohol is produced naturally by many plants and is commonly found in fruits and teas. It is also found in a variety of essential oils including jasmine, hyacinth and ylang-ylang.[2] It is also found in castoreum from the castor sacs of beavers.[3] Benzyl esters also occur naturally.[4]

Preparation

Benzyl alcohol is produced industrially from toluene via benzyl chloride, which is hydrolyzed:

C6H5CH2Cl + H2O → C6H5CH2OH + HCl

Another route entails hydrogenation of benzaldehyde, a by-product of the oxidation of toluene to benzoic acid.[5]

For laboratory use, Grignard reaction of phenylmagnesium bromide (C6H5MgBr) with formaldehyde and the Cannizzaro reaction of benzaldehyde also give benzyl alcohol. The latter also gives benzoic acid, an example of an organic disproportionation reaction.

Reactions

Like most alcohols, it reacts with carboxylic acids to form esters. In organic synthesis, benzyl esters are popular protecting groups because they can be removed by mild hydrogenolysis.[6]

Benzyl alcohol reacts with acrylonitrile to give N-benzylacrylamide. This is an example of a Ritter reaction:[7]

C6H5CH2OH + NCCHCH2 → C6H5CH2N(H)C(O)CHCH2

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