3069-67-8Relevant articles and documents
Investigation of Masked N-Acyl-N-isocyanates: Support for Oxadiazolones as Blocked N-Isocyanate Precursors
Gagné-Monfette, William,Vincent-Rocan, Jean-Fran?ois,Lutes, Owen C.,O'Keefe, Geneviève F.,Jeanneret, Alexandria D. M.,Blanger, Claire,Ivanovich, Ryan A.,Beauchemin, André M.
supporting information, p. 14051 - 14056 (2021/09/14)
In contrast to carbon-substituted isocyanates that are common building blocks, N-substituted isocyanates remain underdeveloped and reports on their N-acyl derivatives (i. e. amido-isocyanates) are exceedingly rare. Herein, amido-isocyanates were investiga
The invention relates to a synthetic pymetrozine intermediate [...] physiologically carbonate method
-
Paragraph 0055; 0057, (2019/04/14)
The invention discloses a method for synthesizing a pymetrozine intermediate (oxadiazole ketone) by utilizing carbonate ester. According to the method, hydrazine hydrate and an acetic acid ester are utilized as raw materials for hydrazine-ester condensation to synthesize acethydrazide; oxadiazole ketone is generated through a ring-closure reaction between acethydrazide and carbonate ester under certain conditions. Such environmental-friendly non-toxic or low-toxic dimethyl carbonate, diphenyl carbonate or dibenzyl carbonate is utilized for replacing previously common virulent phosgene, diphosgene or triphosgene as a carbonylation ring-closure reagent; under the action of catalysts, a ring-closure cyclization reaction is performed for preparation of oxadiazole ketone; virulent phosgene and a great amount of inorganic solid hazardous waste are prevented from generating during a production process, so that major hidden dangers are reduced; the method has the advantages that the process is safe and reliable, reaction conditions are mild and easy to control, after-treatment is convenient, and an environmental-friendly effect is achieved.
Process for producing 2-methyl-1,3,4-oxadiazole-5(4H)-ketone
-
Paragraph 0001-0003, (2017/07/11)
The invention discloses a process for producing 2-methyl-1,3,4-oxadiazole-5(4H)-ketone. The 2-methyl-1,3,4-oxadiazole-5(4H)-ketone is a main chemical finished product. The process comprises the following steps: 1, adding a dichloroethane solution of acethydrazide into a 5,000-liter ring formation kettle, closing a manhole cover, stirring and reducing the temperature to 10 DEG C; 2, checking and starting a tail gas absorption system; 3, after dropwise addition is completed, performing reaction for 24h in a manner that the temperature of the ring formation kettle is controlled to be below 45 DEG C, and after reaction is completed, adding a small amount of NaHCO3 to neutralize a small amount of hydrogen chloride contained in a solution; 4, after reaction is completed, keeping introducing nitrogen for 1h, and collecting and guiding generated HCl tail gas (containing trace diphosgene which does not participate in the reaction), performing two-stage water falling film absorption and one-stage liquid caustic soda bubble absorption, and then discharging through a 25m-high exhaust funnel (No. 1 exhaust funnel); 5, adding measured water into the kettle, and standing for 2h for demixing.