How is butanoic acid prepared starting fromi.An alcoholii.An alkyl halideiii.An alkene

Butanoic acid, also known as butyric acid, can be prepared using different methods starting from various starting materials. Here's how it can be prepared from each of the mentioned starting materials:

i. Preparation from an alcohol:
To prepare butanoic acid from an alcohol, a two-step process can be followed.

Step 1: Oxidation of alcohol to aldehyde:
The alcohol (butanol) is oxidized to the corresponding aldehyde (butanal) using an oxidizing agent such as potassium dichromate (K2Cr2O7) in the presence of sulfuric acid (H2SO4). This reaction is known as alcohol oxidation.

Butanol + [O] → Butanal + H2O

Step 2: Oxidation of aldehyde to carboxylic acid:
The aldehyde (butanal) obtained from the first step is further oxidized to butanoic acid using a stronger oxidizing agent like potassium permanganate (KMnO4) or chromic acid (H2CrO4).

Butanal + [O] → Butanoic acid

ii. Preparation from an alkyl halide:
To prepare butanoic acid from an alkyl halide, a reaction called hydrolysis is employed.

The alkyl halide (such as 1-bromobutane) is reacted with aqueous sodium or potassium hydroxide (NaOH or KOH) under reflux conditions. This reaction is known as nucleophilic substitution.

1-Bromobutane + NaOH → Butanoic acid + NaBr

iii. Preparation from an alkene:
To prepare butanoic acid from an alkene, a two-step process involving hydroboration-oxidation can be utilized.

Step 1: Hydroboration:
The alkene (such as 1-butene) is reacted with borane (BH3) in the presence of a solvent (e.g., tetrahydrofuran, THF). This reaction is called hydroboration and results in the formation of an organoborane compound.

1-Butene + BH3 → Butylborane

Step 2: Oxidation:
The organoborane obtained from the first step is oxidized with hydrogen peroxide (H2O2) and a basic solution (such as sodium hydroxide, NaOH). This oxidation converts the organoborane into butanoic acid.

Butylborane + H2O2 + NaOH → Butanoic acid

These are some common methods for preparing butanoic acid from different starting materials. Keep in mind that there may be alternative or more specific methods depending on the starting material and reaction conditions.