S-Cl bond

Hydrolysis of sulfonyl chlorides to sulfonic acids is often important because many of these acids can best be obtained pure by first preparing and then hydrolysing their chlorides and moreover sulfonyl chlorides are accessible by a variety of routes. 

The most elegant method of converting alkanesulfonyl chlorides into the sulfonic acids is alcoholysis 683 no ester is formed in the absence of acidbinding agents  

Most arenesulfonyl chlorides are readily hydrolysed to the sulfonic acids by boiling with water, alkali, aqueous alcohol, aqueous acetic acid, or concentrated formic acid. Sulfonic esters are formed when alcohols or phenols are used with an acid-binding agent.684,685 

Alkyl benzenesulfonates 686 20-30% sodium hydroxide solution is added dropwise, with vigorous shaking, to benzenesulfonyl chloride (1 part) and the alcohol (1 part), until the alkaline reaction is permanent after considerable shaking and the oil that separates is completely free from chlorine. Benzene and water are added, the two layers are separated, the organic layer is washed and dried, and the solvent and alcohol are removed in a vacuum by means of a water-bath at 30-40° (not higher). This process has afforded the allyl (explosive decomposition on distillation), 2-chloroethyl, b.p. 184°/9mm, 2-bromoethyl, b.p. 185-187°/ 16 mm, and 2-chloro-l-(chloromethyl)ethyl ester, b.p. 200-205°/20 mm, m.p. 50° (from benzene). 

Roos and his co-workers687 have described a general method of preparing simple alkyl toluenesulfonates. Pyridine has been used as acid-binding agent in the preparation of alkyl methanesulfonates,688 yields averaging 80%. 

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Whether the breaking of the C—O and the S—Cl bonds occurs simultaneously, or whether the former occurs first, is still a matter of debate. 

The additional sulfur atom seems to reduce the reactivity of the S—Cl bond to nucleophilic attack cmly to a slight extent. Hydrolysis yields, here too, the symmetrically disubstituted iV,A -bis(trifluoromethylmer-captosulfenyl) urea ... 

According to the first reaction, the S—Cl bond is homolytically cleaved. The radicals thus formed react [Eqs. (b) and (d)] to give the precursor of the end product, which is produced according to Eqs. (c) and (e) together with the newly formed radicals of reaction (a). The appearance of the free radicals CFgS", Cl , and ClFoCS is supported by the presence... 

Di-Ar-chlorothioimino-3,4-dicyanothiophene (384) containing the rare S-chloro-sulfurimino group has been prepared by reaction of 2,5-diamino-3,4-dicyanothiophene with sulfur dichloride (80JA4283). The molecule is planar, with the S—Cl bonds folded inwards. 

It is clear from existing evidence that this reagent suffers S—Cl bond rupture, and may consequently be regarded as an analog of hydrogen chloride in which the place of the proton Juw been taken by a 2,4-dinitrophenylsulfenyl cation The fact that pyridine is a required catalyst suggests that ita function is to assist dissociation of the reagent, perhaps by the process depicted in Eq. (037). 

SOCU from S02, and a breakage at b will result in exchange of active sulfur, which is not observed. Thus, if the S02+ is formed, it is either solvated through the sulfur atoms of solvent molecules (as represented in II) or nonsolvated. It is more likely, however, that only one chloride is lost from each SOCU molecule. The solvated SOC1+ ion, represented as III, retains one S—Cl bond, and upon removal of solvent, the S—0—S linkage is broken at position a but not at 6. 

The intermediate contains a tricoordinate sulfur cation or sulfonium salt. The chloride ion now attacks the other sulfur atom of this intermediate and two molecules of RSC1 result. Each atom of the original disulfide has formed an S-Cl bond. One sulfur atom was a nucleophile towards chlorine and the other an electrophile. 

This reaction is carried out on a large scale in which activated charcoal or FeCl3 is used as a catalyst. The S-Cl bonds in 02SC12 are very reactive, so it is a useful reagent for synthesizing numerous other compounds. 

This compound can function as an acid, but it also contains a highly reactive S-Cl bond that will react with water, alcohols, and so forth. 

If in the molecule S2CI2, the energy of the S—S bond is taken as 52 kcals, each S—Cl bond has an energy of 61 kcals. Such an apportionment of the energy of the molecule is only approximate since in addition to the normal homopolar structure Cl—S—S—Cl, the ionic forms ... 

In the crystal structure at 133 K the sulfur atom has a 3+3-coordination with three secondary intermolecular S--F contacts (2.720-2.972 A) besides the extremely long intramolecular S-C bond (1,978 A) and two S-Cl bonds (1.959 A). A normal-coordinate analysis supports the structural data (310). 

NMR can be used for the characterization of axial hypervalent S-Cl bond and S- O close contact in chloro-A -sulfanes and sulfonium salts 24-26 with or7,4o-substitution in the aromatic ring. The solvent effect has also been investigated CDCI3 is the most favorable for stabilizing the hypervalent S-Cl bond (see Table 5) <2001J(P2)339>. 

We estimate the S-Cl bond length to lie between those for SCI2 and S2CI2 (1.). The value of is calculated from the adopted... 

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