The tail-to-tail dimerization of vinyl compounds catalyzed by an N-heterocycliccarbene was found to show a very broad substrate scope and tolerance to various functional groups. The optimization o...
Method of producing hexamethylene diamine from butadiene
申请人:Degussa AG
公开号:US20030212298A1
公开(公告)日:2003-11-13
The invention relates to the production of hexamethylene diamine from butadiene. The method comprises the successively performed stages of: (i) a catalytic epoxidation of butadiene to 1,2-epoxy-3-butene; (ii) a basically catalyzed addition of hydrogen cyanide to butadiene monoxide to form a reaction mixture containing 3-hydroxy-4-pentene nitrile (3HPN) and 2-hydroxymethyl-3-butene nitrile (2HMBN); (iii) an acidically catalyzed dehydration of the cyanohydrines 3HPN and 2HMBN of stage (ii) to cis/trans-pentadiene nitrile (PDN); (iv) a basically catalyzed addition of the products of stage (iii) to form cis/trans-1,4-dicyanobutene-1 and -2 (DCB); and (v) a catalytic hydrogenation of the isomeric cis/trans-1,4-dicyanobutene of stage (iv) to hexamethylene diamine.
The kinetics and mechanism of the phosphorus-catalysed dimerisation of acrylonitrile
作者:C. Dennis Hall、Nicholas Lowther、Bruce R. Tweedy、Adam C. Hall、Gordon Shaw
DOI:10.1039/a707559f
日期:——
Isopropyl diarylphosphinites (Ar2POPri) catalyse the dimerisation of acrylonitrile (AN) to a mixture of cis- and trans-1,4-dicyanobut-1-ene (cis,trans-DCB-1), trans-1,4-dicyanobut-2-ene (DCB-2) and 2,4-dicyanobut-1-ene (MGN). The kinetics and mechanism of the reaction, which is a potential source of hexamethylenediamine, are reported in detail and the factors which govern rate and selectivity to DCB-1 and DCB-2 rather than MGN are elaborated.
are effective catalyst precursors for the tail-to-tail dimerization of acrylonitrile. Hydrogen pressure is necessary for the catalytic reaction, and the turnover number for dimers is greatly improved in neat acrylonitrile. Under the conditions of 150 °C and 25 atm of H2 (initial pressure at room temperature), the conversion of acrylonitrile is 61% and the yield of tail-to-tail dimers is 42% (selectivity
A process for dimerizing acrylonitrile to produce adiponitrile and/or 1,4-dicyanobutenes comprises contacting acrylonitrile with a catalyst at a temperature of 20 to 250 °C in the presence of hydrogen, said catalyst comprising a polymer support having a ruthenium complex bonded thereto, said polymer support comprising an organic polymer backbone having trivalent pendant atoms selected from P, As, Sb, Bi and N covalently bonded thereto and randomly distributed in said polymer, said ruthenium complex being capable of catalyzing the dimerization of acrylonitrile to adiponitrile and/or 1,4-dicyanobutenes and comprising Ru and at least two homogeneous ligands having at least four ligating bonds bonding to said Ru, the Ru in each ruthenium complex datively bonding to a pendant atom in said polymer support, the Ru/pendant atom ratio in said catalyst being at least 0.001, said complex having on the average no more than one homogeneous phosphine ligand per atom of ruthenium.
Preferred ruthenium complexes are those which are substantially free of homogeneous phosphine ligands. The organic polymer support can be a terpolymer of 2-20% divinyl benzene, 0.4 to 6% para-diphenylphosphenostyrene and the balance styrene.