Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1993-08-10
1997-06-10
Higel, Floyd D.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
549512, 549519, 568 18, 568 22, 568 27, 568 32, C07D30102, C07C38100, C07C38112
Patent
active
056377274
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/GB92/00248 filed Feb. 12, 1992.
This invention relates to the preparation of epoxides from carbonyl compounds using either trimethylsulphonium hydrogen sulphate and/or bis(trimethylsulphonium) sulphate or trimethylsulphoxonium hydrogen sulphate and/or bis(trimethylsulphoxonium) sulphate. It also relates to trimethylsulphonium hydrogen sulphate, trimethylsulphoxonium hydrogen sulphate and bis(trimethylsulphoxonium) sulphate, which are novel compounds, and to processes for their preparation. The invention further relates to processes for preparation of sulphonium ylide, (CH.sub.3).sub.2 S.sup.+ --.sup.- CH.sub.2 and sulphoxonium ylide, (CH.sub.3).sub.2 S.sup.+ (O)--.sup.- CH.sub.2 using these intermediates and a process for the preparation of fungicides and insecticides using these intermediates.
It is well known to prepare epoxides from carbonyl compounds using sulphonium or sulphoxonium salts. In particular, it is known to react dimethyl sulphide with dimethyl sulphate in an organic solvent, and then to contact the trimethylsulphonium methylsulphate so formed with a carbonyl compound in the presence of a strong base to form an epoxide. This epoxidation reaction is believed to proceed via the intermediate generation of the sulphonium ylide, (CH.sub.3).sub.2 S.sup.+ --.sup.- CH.sub.2 or sulphoxonium ylide, (CH.sub.3).sub.2 S.sup.+ (O)--.sup.- CH.sub.2. A disadvantage of the known process is that organic material, in the form of an alkali metal methylsulphate, is present in the effluent. As yell as being environmentally undesirable, methylating agent is lost and this is chemically inefficient. A further disadvantage is that dimethyl sulphate is a carcinogen.
According to the present invention there is provided a process for transforming a carbonyl compound into its corresponding epoxide, which comprises contacting the carbonyl compound with either trimethylsulphonium hydrogen sulphate and/or bis(trimethylsulphonium) sulphate or trimethylsulphoxonium hydrogen sulphate and/or bis(trimethylsulphoxonium) sulphate, in the presence of a base.
The compounds, trimethylsulphonium hydrogen sulphate having the formula: (CH.sub.3).sub.3 S.sup.+.HSO.sub.4.sup.-, trimethylsulphoxonium hydrogen sulphate having the formula: (CH.sub.3).sub.3 S(O).HSO.sub.4, and bis(trimethylsulphoxonium) sulphate having the formula: ((CH.sub.3).sub.3 S(O).).sub.2 SO.sub.4, are novel and form another aspect of the present invention.
The compound, trimethylsulphonium hydrogen sulphate, is a novel compound. Although it is mentioned by name in Czechoslovakian Patent No 254,032, no method or reference is given for its preparation.
Therefore, according to yet another aspect of the present invention, there is provided a process for preparing trimethylsulphonium hydrogen sulphate which comprises reacting together dimethylsulphide, methanol and sulphuric acid at a temperature of from -20.degree. C. to +100.degree. C. (in a sealed system) or from -20.degree. C. to +40.degree. C. (at atmospheric pressure).
Suitably, from 1 to 10 moles of dimethylsulphide, normally about 2 moles, and from 1 to 10 moles of sulphuric acid, normally from 1 to 2 moles, are used for each mole of methanol. The dimethyl sulphide, before it is consumed in the reaction, and any excess used will act as a solvent. Excess sulphuric acid will require to be neutralised at the epoxidation stage by the addition of extra base.
In a typical preparation, the methanol is added slowly, for example dropwise, to a molar excess of dimethyl sulphide, for instance, 2 moles of dimethyl sulphide for each mole of methanol used in the reaction, at a temperature preferably below 25.degree. C., when the reaction is carried out at atmospheric pressure. Concentrated sulphuric acid such as commercially available 98% sulphuric acid solution, may then be added gradually to the stirred mixture maintaining the temperature below 25.degree. C. The time taken for the reaction will depend inter alia on its scale. Where half a mole of methanol (i.e. 16 g) is used, the methanol addi
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Jones Raymond V. H.
Simpson Elizabeth S. C.
Higel Floyd D.
Thomson Marian T.
Zeneca Limited
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