52331-02-9Relevant articles and documents
Preparation method of topramezone
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Paragraph 0075-0077, (2021/01/04)
The invention relates to a preparation method of topramezone. Themethod comprises the following steps of: (1) carrying out oxidation reaction on a compound 5 and an oxidant under the action of a catalyst to obtain a compound 6; (2) carrying out Grignard reaction on the compound 6, magnesium and carbon dioxide to obtain a compound 7; and (3) carrying out condensation reaction on the compound 7 and1-methyl-5-hydroxy pyrazole to obtain topramezone. The structural formula of the compound 5, the structural formula of the compound 6, the structural formula of the compound 7 are described in descriptions of the invention. The preparation method of topramezone has the advantages of few by-products, high purity and yield of topramezone, low wastewater treatment difficulty, low cost, no toxic or side effect in the production process and suitability for industrial production.
Evidence for the Reactive Spin State of 1,4-Dehydrobenzenes
Lockhart, Thomas P.,Bergman, Robert G.
, p. 4091 - 4096 (2007/10/02)
Two approaches have been used to investigate the spin state(s) of 1,4-dehydrobenzene produced in the solution thermolysis of diethynyl olefins.One method relies on the "spin correlation effect" which postulates a relationship between the spin state of a caged radical pair and the ratio of cage and escape reactions (C/E) which may occur in the pair.When the 2,3-di-n-propyl-1,4-dehydrobenzene biradical (4) abstracts hydrogen from 1,4-cyclohexadiene, a radical pair is generated.If a mixture of 1,4-cyclohexadiene-d0 and-d4 is employed, it is possible, by performing a VPC-MS analysis, to determined the C/E ratio leading from the radical pair to the reduced product, o-dipropylbenzene (10).When this method was applied to the reaction of (Z)-4,5-diethynyl-4-octene (3), C/E was found to be 0.6, independent of the concentration of 1,4-cyclohexadiene (between 0.1 and 10 M) in the chlorobenzene reaction solution.This result indicates the presence of the singlet state of 4 in the reaction of 3.Additional support for this analysis came from the reaction of 3,4-dimethyl-1,5-hexadiyn-3-ene (11) in hexachloroacetone solvent in a 1H NMR probe.The single polarized signal (emission) observed is attributed to the major product of the reaction, 1,4-dichloro-2,3-dimethylbenzene (12), obtained by chlorine abstraction from the solvent.The interpretation of this result indicates solvent trapping of the singlet state of the intermediate 2,3-dimethyl-1,4-dehydrobenzene, consistent with the chemical trapping study.These experimental approaches indicate that at least a substantial portion of the products formed from 1,4-dehydrobenzenes at elevated temperatures arise from the singlet state of the biradical.This suggests that either the singlet is the ground state or, if the triplet is lower in energy, the rate of intersystem crossing from the singlet must be 9 s-1 at 200 deg C.
