Reed reaction

The Reed reaction is a chemical reaction that utilizes light to oxidize hydrocarbons to sulfonyl chlorides. The reaction performs via the free radicals. First, the light makes a molecule of chlorine dissociate homolytically, then an chlorine atom produced attacks the hydrocarbon chain to form hydrogen chloride what results in the formation of alkyl free radical. Then SO₂ as an electron donor bonds to the reaction center, forming an sulfonyl radical. Finally, the least one attacks another chlorine molecule to produce an sulfonyl chloride and a new chlorine atom which continues the reaction chain.

See also: Chain reaction

The Reed reaction

Chain initiation:

$Cl_{2}{\xrightarrow {h\nu }}2Cl\cdot .$

Chain propagation steps:

$R-H+\cdot Cl\longrightarrow R\cdot +HCl$

$R\cdot +:\!SO_{2}\longrightarrow R-{\dot {S}}O_{2}$

$R-{\dot {S}}O_{2}+Cl_{2}\longrightarrow R-SO_{2}-Cl+Cl\cdot .$

The resulting sulfonyl chlorides are widely used in the detergent industry as a raw material.

Under particular circumstances (40–80 °C) only chlorination of alkane may take place.

$R-H+SO_{2}Cl_{2}\rightarrow \ R-Cl+SO_{2}+HCl$

References

• C. F. Reed, U.S. patent 2,046,090; U.S. patent 2,174,110; U.S. patent 2,174,492.
• Asinger, F. et al. Ber. 1942, 75, 34.
• Asinger, F. et al. Ber. 1942, 75, 42.
• Asinger, F. et al. Ber. 1942, 75, 344.
• Helberger, J. H.; Manecka, G.; Fischer, H. M. Ann. 1949, 562, 23.