Question

How us butan -2-ol prepared from ethanal by using grignard reagent?

Answer 1

Ethanol and PCC react to give ethanal(aldehyde).

Ethanal and dilute NaOH or KOH react with heating to form aldol product.

With H2/ Ni, alkene group(double bond) becomes into alkane group and aldehyde group becomes to a alcoholic group.

Answer 2

Answer:

A chemical addition reaction in which a nucleophile forms a sigma bond with an electron-deficient molecule is known as a nucleophilic addition reaction.

Explanation:

When ethanal (CH₃CHO) is treated with ethyl magnesium bromide (CH₃CH₂MgBr) i.e., Grignard reagent followed by the workup step, it results in the formation of 2-butanol or butan-2-ol (CH₃CH(OH)CH₂CH₃).

The reaction is as follows below:

CH₃CHO + CH₃CH₂MgBr → CH₃C(OMgBr)(H)CH₂CH₃ → CH₃CH(OH)CH₂CH₃

So, the above reaction is a nucleophilic addition reaction. In general, nucleophilic addition reactions of carbonyl compounds may be divided into three phases.

• A sigma bond is formed between the nucleophile and the electrophilic carbonyl carbon.

• The carbon-oxygen pi bond has now been broken, resulting in the formation of an alkoxide intermediate (the bond pair of electrons are transferred to the oxygen atom).

• The alcohol derivative is produced by the protonation of the alkoxide.

Hence, the butan-2-ol prepared from ethanal by using Grignard reagent i.e., ethyl magnesium bromide.

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