28182-81-2Relevant articles and documents
Enhanced activity of CuO/ZnO catalyst on the decomposition of dimethylhexane-1,6-dicarbamate into dimethylhexane-1,6-diisocyanate
Kim, Jinsung,Jeong, Cheonwoo,Lee, Jae-Hong,Suh, Young-Woong
, p. 3787 - 3796 (2018)
To decompose dimethylhexane-1,6-dicarbamate (HDC) to hexamethylene diisocyanate (HDI), mixed CuO and ZnO catalysts with Cu/(Cu + Zn) ratio of 4 and 8% were prepared by coprecipitation (CP), sequential precipitation (SP) and incipient wetness impregnation (IW). The SP-derived CuO/ZnO catalysts showed higher HDC yields than those derived by CP and IW. The IW method produced CuO/ZnO catalysts consisting of larger CuO and ZnO particles compared to the two precipitation methods. The CP method led to substitution of Zn2+ by Cu2+ in the hydrozincite precursor phase, resulting in higher BET and Cu surface areas of CuO–ZnO catalysts due to intimate intergrowth of nano-sized particles. However, the inherent character of ZnO in the CP-derived catalysts was modified by interfacial contact between CuO and ZnO identified by UV–visible and Raman spectra. In contrast, the properties of CuO and ZnO, as well as the relatively large surface areas, were kept in the SP-derived catalysts owing to deposition of Cu precipitates to fully aged Zn precipitates. This is believed to be a benefit of the SP method for the reaction. Therefore, our preparation approach has great potential to be extended to various mixed oxide catalysts.
Synthesis of isocyanates from carboxylic acids using diphenylphosphoryl azide and 1,8-bis(dimethylamino)naphthalene
Gilman,Otonari
, p. 335 - 341 (1993)
A simple phosgene-free method for the synthesis of high-purity isocyanates from carboxylic acids was developed using diphenylphosphoryl azide and 1,8-bis(dimethylamino)naphthalene. Yields for evaluated monoisocyanates ranged from 60.0% to 81.5%.
METHOD OF PREPARING DIISOCYANATE COMPOSITION
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Paragraph 0248-0249; 0283-0285, (2021/06/11)
In the embodiments, an aqueous hydrochloric acid solution instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by controlling the size of the diamine hydrochloride composition, the b* value according to the CIE color coordinate of the diamine hydrochloride composition, or the content of water in the diamine hydrochloride composition within a specific range.
METHOD FOR PRODUCING CARBAMATE AND METHOD FOR PRODUCING ISOCYANATE
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, (2021/06/22)
The present invention provides a method for producing a carbamate that includes a step (1) and a step (2) described below: (1) a step of producing a compound (A) having a urea linkage, using an organic primary amine having at least one primary amino group per molecule and at least one compound selected from among carbon dioxide and carbonic acid derivatives, at a temperature lower than the thermal dissociation temperature of the urea linkage; and(2) a step of reacting the compound (A) with a carbonate ester to produce a carbamate.