The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 22, 2015
Filed:
Dec. 09, 2013
Kingchem Llc., Allendale Park, NJ (US);
Zheqing Wang, Union City, CA (US);
Angang Wang, Dalian, CN;
Yongcan Wang, Dalian, CN;
Zhenwei Li, Dalian, CN;
KINGCHEM LLC., Allendale Park, NJ (US);
Abstract
The disclosure provides a process for the preparation of alkyl 3-difluoromethyl-1-methyl-1H-pyrazole-4-caboxylate and its analogs. The process includes a reaction workup method for Claisen condensation, wherein the enolate salt is acidified after removing remaining starting material and byproducts such as, ethanol and excessive ethyl acetate. The process also includes a method for completely drying alkyl difluoroacetoacetate and its analogs before use in the next step by reacting trialkyl orthoformate with the residual water. The process includes using NaCOand/or KCOto promote the ring-closure reaction to produce the alkyl 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylate. The process also includes effectively removing the regioisomer, alkyl 3-difluoromethyl-2-methyl-1H-pyrazole-4-caboxylate formed as a byproduct of the ring closure by a precipitation in a mixed solvent system and thereby eliminating the need for recrystallization of the final product.