Investigations on the Lewis-Acids-Catalysed Electrophilic Aromatic Substitution Reactions of Thionyl Chloride and Selenyl Chloride, the Substituent Effects, and the Reaction Mechanisms. (December 2013)

• Record Type: Journal Article
• Authors: Sun, Xiaoping; Haas, David; McWilliams, Samantha; Smith, Benjamin; Leaptrot, Katrina
• Is Part Of: Journal of chemical research. Volume 37:Number 12(2013)
• Page Start: 736
• Page End: 744
• Publication Date: 2013-12
• Subjects: organosulfur -- organoselenium -- auto-redox -- aromatic -- CH substitution -- functionalisation; Chemistry -- Research -- Periodicals; Chemistry -- Periodicals; 540.5
• DOI: 10.3184/174751913X13842832780853
• Languages: English
• ISSNs: 1747-5198

Abstract

The previously established aluminium-chloride-(AlCl3 )-catalysed electrophilic aromatic substitution (EAS) of benzene (PhH) with thionyl chloride (SOCl2 ) has been extended to toluene (PhCH3 ), chlorobenzene (PhCl), and phenol (PhOH). –CH3 was found to be mainly a para -director with a minor ortho -directing effect on the EAS reactions giving diaryl sulfoxides (Ar2 SO). –Cl was found to be exclusively a para -director for formation of Ar2 SO. All the –CH3, –Cl, and –OH groups were shown to be exclusive para -directors for formation of diaryl sulfides (Ar2 S) from the EAS reactions. Although the reactions of PhH and PhCH3 with SOCl2 in the presence of AlCl3 gave the major Ar2 SO and minor Ar2 S at ambient temperature, the phenol (PhOH) reaction was shown to give only the reduced sulfide ( p -HOC6 H4 )2 S with no sulfoxide ( p -HOC6 H4 )2 SO formed. The mixed diaryl sulfoxides ArSOAr' (Ar, Ar'=C6 H5, p -CH3 C6 H4 ; C6 H5, o -CH3 C6 H4 ; and C6 H5, p -ClC6 H4 ) were produced in the AlCl3 -catalysed reactions of SOCl2 with molar 1:1 PhH–PhX mixtures (X=CH3 and Cl). Efforts to enhance the yield of S -aryl arenesulfonothioates ArSO2 SAr (Ar=Ph, p -CH3 C6 H4, and p -ClC6 H4 ) from the AlCl3 -catalysed EAS reactions of SOCl2 were made, showing that decreasing the molar ratios of ArH/SOCl2 or lowering the temperature resulted in an increase in the product yield. A detailed mechanism has been proposed to account for the formation of ArSO2 SAr. The Lewis-acid-MCl3 -(M=Al and Fe)-catalysed EAS reactions of PhH with selenyl chloride (SeOCl2 ) were demonstrated to give the reduced diphenyl selenide (Ph2 Se) and diphenyl diselenide (PhSeSePh) via novel auto-redox processes in selenium of the key EAS intermediates.