Preparation of N-cyanoimidate herbicide intermediates
AssigneeE. I. Du Pont de Nemours and Company
InventorEdward K. W. Wat
Life of this patent
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Abstract
Certain N-cyanoimidates are prepared by (a) contacting a propendimidate dihydrohalide salt with two equivalents of a base to produce a bisimidate; (b) contacting the bisimidate with cyanogen chloride to produce a mixture of N-cyanoimidate and a monohydrohalide bisimidate salt; (c) isolating the N-cyanoimidate. The N-cyanoimidate may, by heating, be converted to a pyrimidine, useful as a herbicide intermediate.
Claims7
A process for preparing a pyrimidine compound of the formula ##STR4## where X and Y are independently oxygen or sulfur;
- R.sup.1 and R.sup.2 are independently C.sub.1 -C.sub.4 alkyl, (CH.sub.2).sub.n OR.sup.3, CH.sub.2 CH.sub.2 Cl or CH.sub.2 CF.sub.3 ;
- R.sup.3 is C.sub.1 -C.sub.4 alkyl;
- and
- n is 1 or 2;
- provided that:
- (1) when R.sup.1 is CH.sub.2 CH.sub.2 Cl or CH.sub.2 CF.sub.3, then X is 0;
- and
- (2) when R.sup.2 is CH.sub.2 CH.sub.2 Cl or CH.sub.2 CF.sub.3, then Y is 0;
- comprising
- (a) contacting a dihydrohalide salt of the formula:
- ##STR5## where X, Y, R.sup.1 and R.sup.2 are as defined above;
- and where Z is F, Cl or Br,
- with two mole equivalents of a base to produce a bisimidate;
- and
- (b) contacting the bisimidate with cyanogen chloride to product a mixture of an N-cyanoimidate and a monohydrohalide bisimidate salt;
- (c) isolating the N-cyanoimidate from the reaction mixture;
- and
- (d) heating the resulting N-cyanoimidate at a temperature sufficient to induce ring closure.
A process for preparing a compound of the formula ##STR6## where X and Y are independently oxygen or sulfur;
- R.sup.1 and R.sup.2 are independently C.sub.1 -C.sub.4 alkyl, (CH.sub.2).sub.n OR.sup.3, CH.sub.2 CH.sub.2 Cl or CH.sub.2 CF.sub.3 ;
- R.sup.3 is C.sub.1 -C.sub.4 alkyl;
- and
- n is 1 or 2;
- provided that:
- (i) when R.sup.1 is CH.sub.2 CH.sub.2 Cl or CH.sub.2 CF.sub.3, then X is 0, and
- (ii) when R.sup.2 is CH.sub.2 CH.sub.2 Cl or CH.sub.2 CF.sub.3, then Y is 0;
- comprising
- (a) contacting a suspension of a dihydrohalide salt of the formula ##STR7## where X, Y, R.sup.1 and R.sup.2 are as defined above, and where Z is F, Cl or Br,
- in methylene chloride with two mole equivalents of sodium or potassium carbonate at a temperature in the range of about -10.degree. to 50.degree. C. to produce a bisimidate;
- (b) contacting a solution of the bisimidate in methylene chloride with cyanogen chloride at a temperature of about 0.degree. to 80.degree. C. to produce a mixture of an N-cyanoimidate and a monohydrohalide bisimidate salt;
- (c) isolating the N-cyanoimidate;
- (d) recycling the monohydrohalide bisimidate salt by
- (i) contacting the monohydrohalide bisimidate salt with one mole equivalent of sodium or potassium carbonate under the conditions of step (a) to produce a bisimidate, and
- (ii) contacting the bisimidate with cyanogen chloride under the conditions of step (b) and isolating the N-cyanoimidate formed thereby;
- and
- (e) heating the resulting N-cyanoimidate at a temperature sufficient to induce ring closure.
Dependencies are inferred from the claim text.