Reed reaction

Sulfochlorination as it denotes the replacement (substitution) of hydrogen through the Chlorsulfongruppe ( SO2Cl ) in alkanes. This reaction is a free radical substitution and is also referred to as Reed - reaction.

Overview reaction

Alkanes react with a mixture of sulfur dioxide and chlorine to alkylsulfonyl chlorides:

As a byproduct hydrogen chloride.

Reaction sequence

Start reaction

The chain reaction is initiated by the supply of suitable energy, such as light. So it comes to homolytic bond cleavage of the Cl - Cl bond:

The chlorine molecule is cleaved homolytically. That is shared ( in contrast to the heterolytic ) into two equal halves (chlorine radicals). The forced bond breaking by electromagnetic radiation is also known as radiolysis.

Propagation reactions

A chlorine radical reacts with the alkane to form an alkyl radical, and hydrogen chloride:

Subsequently, the alkyl radical combines with the sulfur dioxide:

Finally, the alkylsulfonyl created with the release of a new chlorine radical:

The chain reaction begins again, ie, chlorine radical is formed in the final step, reacts with the alkane to form an alkyl radical, and hydrogen chloride, etc.

Chain termination reactions

Chain termination occurs by recombination of radicals:

The excess energy is degraded by Stoßrelaxation.

The green compound is drawn for the newly formed bond between the radicals. The sulfochlorination is not selective, that is, one often obtains a mixture stellungsisomerer alkylsulfonyl chlorides.

Variants of the reaction

Under certain conditions ( 40-80 ° C) takes place only chlorination of alkane:

Application

The alkylsulfonyl produced by this reaction are important intermediates in the industrial synthesis of detergents.