Tliionyl Chloride

It may be pointed out that dehydration of p hydroxy esters with fused potassium hydrogen sulphate, acetic anhydride, phosphoric oxide or with tliionyl chloride in benzeue solution leads to ap unsiiturated esters containing some PY-unsaturated ester the proportion of the latter depends not only upon the structure of the ester but also upon the dehydrating agent used. Elehydration occasionally occurs during the reaction itself or upon attempted distillation. 

Tlie Ca substituent effects have been experimentally studied by synthesizing and investigating the A -(l,2,2,2-tetrachloroethyl)pyridinium chloride (43). Tlie synthesis of 43 follows the standard three-component reaction. Tliionyl chloride, trichloroacetaldehyde, and pyridine were reacted at 0°C in MeCN to give this salt in excellent yield (Scheme 31). 

Phosphorus pentachloride effects a gradual removal of one atom of oxygen from sulphuryl chloride, with formation of tliionyl chloride,... 

This ester acid chloride is prepared by allowing 100 g. (0.63 mole) of redistilled commercial methyl hydrogen adipate (b.p. 155 156 /7 mm., 172 173°/13 mm.) to stand overnight at room Icmpcralurc with 150 g. (1.25 moles) of tliionyl chloride. 

Phosgene (165) or tliionyl chloride in the presence of an acid catalyst (166) gives good yields of 4-chlorobutyryl chloride. Heating butyrolactone and thionyl chloride in an alcohol gives good yields of 4-chlorobutyric esters (167). 

Tliionyl chloride. Heat. Plienyimercuric chloride. Hc umanu a.iid ivochllM, /Jt r 1883, i6, 1625. 

Halogenated ribonucleotides,8 Ribonucleosides can be converted conveniently into 5 -chlorinated and 5 -brominated ribonucleosides by reaction with either tliionyl chloride or thionyl bromide in combination with HMPT. For example, 5 -chloro-5 -desoxycytidine (1) and 5 -bromo-5 -desoxyadenosine (2) have been prepared in satisfactory yields in this way. 

J. H. Russel, O. Schindler, and T. Reichstein, Heh., 43,167 (1960) Dimeth>lformaiiiide-Tliionyl chloride (Vilsmeier reagent ). 

Tliionyl halides and A-heteroaromatics are known to be in equilibrium with the corresponding A-(halosulhnyl)heteroarylium halides. N-(Chlorosulhnyl)pyridinium chloride (36), for example, readily reacts with a second molecule of pyridine to give the A-[l-chlorosulhnyl-l,4-dihydro-pyridine-4-yl]pyridinium chloride (37a). The intermediate 37a is probably involved in the preparation of A-(pyridine-4-yl)pyridinium chloride hydrochloride (37b). However, the authors could not detect either 37a or 37b in their experiments (91CB2013) (Scheme 10). 

Acetyl chloride was formerly manufactured by the action of tliionyl cliloiide [7719-09-7], Cl2OS, on gray acetate of lime, but tliis route has been largely supplanted by the reaction of sodium acetate or acetic acid and phosphorus trichloride [7719-12-2] (24). A similar route apparently is still being used in the Soviet Union (25). Both pathways are inherently costly. 

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