2.4- Dinitrobenzenesulphenyl chloride

Dinitrobenzenesulphenyl chloride 3.5- Dinitrobenzoic acid (ii) N-Nitro compounds... 

Kinetic studies of the addition of 2,4-dinitrobenzenesulphenyl chloride to cyclohexene in the presence of LiC104 have been interpreted in terms of an ion-pair mechanism. A similar conclusion has been arrived at for addition of (SCN)2 to cyclohexene and ring-substituted styrenes, RC6H4CH=CH2 (R = H, 4-Me, 4-C1, 3-C1)255. 

The alkenes are distinguished from the alkanes by their solubility in concentrated sulphuric acid and their characteristic reactions with dilute potassium permanganate solution and with bromine. Characterisation may be based upon the determination of their physical and/or spectral properties. Characterisation by way of solid adducts with nitrosyl chloride has been quite widely used in the terpene field the preparation of adducts with 2,4-dinitrobenzenesulphenyl chloride is described below (see also Section 8.1.1, p. 1128). 

Dinitrobenzenesulphenyl chloride reacts in polar solvents (acetone, 1,2-dichloroethane, acetic acid and dimethylformamide) with alkenes to yield crystalline adducts, the / -chloroalkyl-2,4-dinitrophenyl sulphides, e.g. ... 

Detailed investigation of C-14 KIE in simple electrophillic addition reactions has been presented by Kanska and Fry610-612 regarding the mechanism of addition of 2,4-dini-trobenzensulphenyl chloride to substituted styrenes labelled with C-14. Additions of 2,4-dinitrobenzenesulphenyl chlorides to / -substituted a- and -labelled styrenes have been carried out in acetic acid at 30.1 °C (equation 267) ... 

Electrophilic addition of sulphenyl halides to alkenes occurs, by all the evidence, via cyclic thiiranium ions (Mueller, 1969) and a comparison of the rates of addition to the double and triple bond would be quite interesting. Unfortunately, direct kinetic data for strictly comparable and typical cases are not available. Phenylacetylene has been reported (Kharasch and Yannios, 1964) to react 102 times slower than styrene (in acetic acid at 25°) with 2,4-dinitrobenzenesulphenyl chloride. On the other hand, Thaler (1969), by means of competitive experiments carried out in dilute paraffin solutions at — 70°, estimated that methane-sulphenyl chloride adds to mono- (and di-)alkylacetylenes 50-100 times more slowly than to the corresponding alkenes (cis) (but only ca. twice slower than to trans dialkylethylenes). The paucity of information does not allow generalizations and further work in this area seems desirable also with respect to the much larger rate differences observed in those bromine additions to triple and double bonds which also occur via bridged species. 

The effective electrophilicity of weak electrophiles, e.g. 2,4-dinitrobenzenesulphenyl chloride, are appreciably increased in addition reactions, e.g. to norbornene, in the presence of strong electrolytes such as LiC104 the proportion of Wagner-Meerwein rearrangement products is thereby increased. 

A new site-selective dehydration can convert allylic alcohols (64) and (66) into the dienes (65) and (67) respectively, using 2,4-dinitrobenzenesulphenyl chloride in triethylamine. The intermediate selenenate ester presumably undergoes [2,3] sigmatropic rearrangement to the allyl selenoxide, which then fragments to the diene. Palladium diacetate-triphenylphosphine appears to be an effective catalyst for the elimination of acetic acid or phenol from allylic acetates or phenyl ethers respectively, leading to 1,3-dienes in high yield. ... 

---