Methyl hydrogen sulfate

R methyl hydrogen sulfate Organo hydrogen sulfates (RO)3 O JT ... 

The only commercially important dialkyl sulfates are dimethyl sulfate and diethyl sulfate. Estimated worldwide production in 1996 for dimethyl sulfate was 90,000 metric tons per year. Dimethyl sulfate was initially made by vacuum pyrolysis of methyl hydrogen sulfate ... 

Later it was synthesized in a batch process from dimethyl ether and sulfur thoxide (93) and this combination was adapted for continuous operation. Gaseous dimethyl ether was bubbled at 15.4 kg/h into the bottom of a tower 20 cm in diameter and 365 cm high and filled with the reaction product dimethyl sulfate. Liquid sulfur thoxide was introduced at 26.5 kg/h at the top of the tower. The mildly exothermic reaction was controlled at 45—47°C, and the reaction product (96—97 wt % dimethyl sulfate, sulfuhc acid, and methyl hydrogen sulfate) was continuously withdrawn and purified by vacuum distillation over sodium sulfate. The yield was almost quantitative, and the product was a clear, colorless, mobile Hquid. A modified process is deschbed in Reference 94. Properties are Hsted in Table 3. 

Sulfuric acid can form ester derivatives with alcohols, though since it is a dibasic acid (pAla — 3, 2) it can form both mono- and di-esters. Thus, acid-catalysed reaction of methanol with sulfuric acid gives initially methyl hydrogen sulfate, and with a second mole of alcohol the diester dimethyl sulfate. Though not shown here, the mechanism will be analogous to the acid-catalysed formation of carboxylic acid esters (see Section 7.9). 

Because formamidine hydrochloride is extremely deliquescent, considerable care must be exercised in its preparation if satisfactory results are to be achieved. Furthermore, formamidine hydrochloride cannot be used directly in most condensation reactions it must be treated first with a mole of base to liberate free formamidine. The same restriction applies to the metho-sulfate salt of formamidine in addition, complications in synthesis may be anticipated in this latter case because methyl hydrogen sulfate itself is an effective methylating agent.6... 

Catalytica A catalytic process for making methanol from methane via methyl hydrogen sulfate. Both yield and selectivity are good, but the process requires the recycle of large quantities of sulfuric acid and so has proved uneconomic and has never been operated. The catalyst is a platinum compex. If a catalyst could be devised that would make the process a hundred times faster, the process might be economic. 

Alkyl Sulfates. The alkyl sulfates used most frequently are dimethyl sulfate, methyl hydrogen sulfate, and diethyl sulfate. Sulfates with longer... 

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