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Chapter 18: Problem 413

Chloroform was at one time synthesized commercially by the action of sodium hypochlorite on ethanol. Formulate the reactions that might reasonably be involved. What other types of alcohols might be expected to give haloforms with halogens and base?

Short Answer

Expert verified
The synthesis of chloroform from ethanol and sodium hypochlorite occurs through the haloform reaction mechanism, which involves conversion of ethanol to acetaldehyde, followed by the formation of chloroform. The overall balanced reaction for this process is: \(CH_3CH_2OH + 4NaOCl \rightarrow CHCl_3 + NaHCOO + 3NaCl + 2H_2O\). Suitable alcohols for the haloform reaction include primary and secondary alcohols, such as methanol, 1-propanol, 1-butanol, isopropanol, and cyclopentanol, which can be oxidized to carbonyl compounds containing a hydrogen atom bonded to the carbonyl carbon.

Step by step solution

01

Identify the reactants

In this case, we are given the reactants: sodium hypochlorite (NaOCl) and ethanol (CH3CH2OH).
02

Write the haloform reaction mechanism

The haloform reaction involves the conversion of an alcohol to a haloform through the use of a halogen and a base. For the synthesis of chloroform, the halogen is chlorine (Cl) and the base is sodium hypochlorite (NaOCl). Here is a general mechanism for the haloform reaction: 1. The sodium hypochlorite (NaOCl) dissociates into \(Na^+\) and \(OCl^-\) ions in the solution. 2. The hydroxide ion (from the base) reacts with the alcohol, converting it into a carbonyl compound. 3. The halogen (here, Cl) reacts with the carbonyl compound to form a haloform and a carboxylate ion.
03

Formulate the reaction for chloroform synthesis

Using the general mechanism from Step 2, we can write the reaction for chloroform synthesis as follows: 1. Dissociation of sodium hypochlorite: \(NaOCl \rightarrow Na^+ + OCl^-\) 2. Conversion of ethanol to acetaldehyde: \(CH_3CH_2OH + OCl^- \rightarrow CH_3CHO + Cl^- + H_2O\) 3. Formation of chloroform: \(CH_3CHO + 3OCl^- \rightarrow CHCl_3 + 3Cl^- + HCOO^-\) 4. Complete balanced reaction: \(CH_3CH_2OH + 4NaOCl \rightarrow CHCl_3 + NaHCOO + 3NaCl + 2H_2O\)
04

Identify other suitable alcohols

The haloform reaction occurs with alcohols that can be oxidized to carbonyl compounds containing a hydrogen atom bonded to the carbonyl carbon. This includes primary and secondary alcohols. Primary alcohols will yield methyl ketones, while secondary alcohols will yield haloforms directly. Some examples of primary alcohols that might give haloform are methanol, 1-propanol, and 1-butanol. Examples of secondary alcohols include isopropanol and cyclopentanol.

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