- Preparation method of 2, 6-dichloropyrazine
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The invention discloses a preparation method of 2, 6-dichloropyrazine. The method comprises the following steps: taking glycine and glyoxal as raw materials, carrying out ammoniation and cyclization reactions to prepare 2-hydroxypyrazine sodium; and reacting 2-hydroxypyrazine sodium with thionyl chloride under the catalytic action of N,N-diisopropylethylamine to prepare 2-chloropyrazine; wherein pyridine is used as a solvent, and 2-chloropyrazine is subjected to chlorination of chlorine to obtain 2,6-dichloropyrazine. The method has the advantages that the raw material namely glycine is cheapand easily available, and phosphorus oxychloride is not used as a chlorination reagent, so that the generation of organic phosphorus-containing wastewater is greatly reduced, and an effective way is provided for efficient green industrial production of 2, 6-dichloropyrazine.
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Paragraph 0034; 0040; 0053-0061
(2020/04/22)
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- Novel pyrazines from the myxobacterium Chondromyces crocatus and marine bacteria
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The volatiles released by two strains of the myxobacterium Chondromyces crocatus and seven strains of marine Alpha-proteobacteria from the North Sea were collected using the CLSA or SPME headspace methods and analysed by GC-MS. In the extracts of C. crocatus 27 pyrazines were identified, belonging to different classes. 2,5-Dialkylpyrazines and related 3-methoxy-2,5- dialkylpyrazines dominated. Several pyrazines like 2-(1-methylethenyl)-5-(1- methylethyl)-pyrazine (7) and 3-methoxy-2,5-dialkylpyrazines with methyl, isopropyl, isobutyl or sec-butyl side-chains were obtained from natural sources for the first time. It was essential for the identification to rely on synthetic reference materials, which were obtained using Fuerstner's iron-catalysed coupling of chloropyrazines with Grignard reagents or condensation of azido ketones as key steps. The synthetic material allowed the identification of two previously unknown attractants of bacterial origin for the pineapple beetle Carpophilus humeralis, namely 3-methoxy-2-(1-methylpropyl)-5-(2-methylpropyl) pyrazine (17) and 3-methoxy-2,5-bis(1-methylpropyl)pyrazine (52). Several 2,5-dialkylpyrazines were identified in the extracts of the marine Alphaproteobacteria. The unique 2,5-dimethyl-3-(methylsulfanyl)pyrazine (67) represents a new type of natural pyrazine. Our results, together with literature reports, show that pyrazines are an important class of bacterial volatiles which might be more widespread than previously thought. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Dickschat, Jeroen S.,Reichenbach, Hans,Wagner-Doebler, Irene,Schulz, Stefan
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p. 4141 - 4153
(2007/10/03)
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- Studies on Pyrazines. 29. High Regioselective Synthesis of Chloropyrazines from 3-Substituted Pyrazine 1-Oxides
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Reaction of 3-methoxy- or 3-chloropyrazine 1-oxides with refluxing phosphoryl chloride in the presence of amine led to a high regioselective formation of 3-substituted 2-chloropyrazines.In contrast, the use of chloroacetyl chloride instead of phosphoryl chloride enabled different regioselectivity to yield 6-substituted 2-chloropyrazines, particularly 3-methoxycarbonylpyrazine 1-oxide was almost exclusively converted into methyl 6-chloropyrazinecarboxylate under conditions without the amine.
- Sato, Nobuhiro,Fujii, Megumi
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p. 1177 - 1180
(2007/10/02)
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