14795-13-2Relevant academic research and scientific papers
Interpretation of the mechanism of 3,3′-dichloro-4,4′-diamino diphenylmethane synthesis over HY zeolites
Ruan, Xiao,Wang, Qiang,Wei, Feng,Yang, Li,Zhao, Yingxian
, p. 34719 - 34728 (2020/10/12)
Catalytic activities of zeolites HY, Hβ and HZSM-5 in the heterogeneous synthesis of 3,3′-dichloro-4,4′-diaminodiphenyl methane (MOCA) fromo-chloroaniline and formaldehyde were pre-screened in an autoclave, and HY demonstrated better performance than others. Kinetic behaviors of MOCA synthesis over HY(11) were further investigated in a fixed bed continuous flow reactor, and under the conditions of the catalyst bed volume = 20 mL (8.14 g),n(o-chloroaniline) : n(HCHO) = 4 : 1, LHSV = 3.5 h?1, 0.5 MPa and 443 K, HCHO conversion and MOCA selectivity steadily fluctuated at high levels of 90-92% and 75-77% during 16 h, respectively. Catalysts were characterized by BET, NH3-TPD and XRD, products analyzed by HPLC, and reaction intermediates identified by LC/MS and1H NMR. The mechanism of MOCA synthesis has been interpreted in detail, which also suggested that deposition of basic intermediates on active sites and accumulation of polymeric by-products in pore channels of the catalyst could cause significant decay of HY(11) activity and selectivity under severe conditions. Supplementary tests on catalyst regeneration confirmed that the acidity and surface area of spent HY(11) could be well recovered after burning off the deposited by-products.
Method for continuously preparing 3, 3'-dichloro-4, 4'-diaminodiphenyl methane
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Paragraph 0036; 0046-0047; 0052-0053; 0058-0059; 0064; 0070, (2020/09/30)
The invention relates to a method for continuously preparing 3, 3'-dichloro-4, 4'-diaminodiphenyl methane, which comprises the following steps: respectively continuously and simultaneously dropwise adding a hydrochloric acid solution, o-chloroaniline and a formaldehyde aqueous solution into a primary reaction kettle to carry out salification and condensation reaction; carrying out continuous rearrangement reaction and neutralization reaction by adopting a double-kettle switching mode; and carrying out continuous oil-water separation and continuous washing on the product. The purity and chromaticity stability of the obtained MOCA product are obviously improved. According to the invention, the ubiquitous problems of easy discoloration of MOCA and unreacted o-chloroaniline due to long-time heat storage, unstable chroma of the MOCA product, limited capacity scale and the like in the prior art are effectively solved, moreover, the synthesis process is automatically and continuously controlled, the overall production efficiency is remarkably improved, the acid consumption, the alkali consumption and the salt-containing wastewater discharge amount are remarkably reduced, the environmentalprotection effect is remarkably enhanced, the operation is simple, the economic cost is low, the capacity scale of a single production line is large, and the method is suitable for popularization andapplication.
Method for preparing polyurethanes using 3,9-bis(2-hydrazidoethyl)-2-4,8,10-tetraoxaspiro-[5,5]-undecane as chain extender
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, (2008/06/13)
Polyurethane is prepared by reacting a prepolymer having terminal isocyanate groups with 3,9-bis(2-hydrazidoethyl)-2,4,8,10-tetraoxaspiro-[5,5]-undecane.
