GB1419155A - Electrolytic hydrodimerization process - Google Patents

Abstract

1419155 Electrohydrodimerization process MONSANTO CO 3 Sept 1973 [5 Sept 1972 4 April 1973 6 Aug 1973] 41390/73 Heading C2C [Also in Division C7] A process for hydrodimerizing an olefinic compound (such as acrylonitrile) having the formula R 2 C = CRX wherein -X is -CN, -CONR 2 or -COOR<SP>1</SP>, R is H or R<SP>1</SP>, and R<SP>1</SP> is C 1 -C 4 alkyl, comprises electrolysing an aqueous solution having dissolved therein (a) at least 0À1% by weight of the olefinic compound, (b) at least 10<SP>-5</SP> g. mol./l. of quaternary ammonium cations and (c) at least 0À1% by weight of conductive salt in contact with a cathodic surface, there being included in the solution in a concentration sufficient to inhibit (i.e. lower) formation of hydrogen at the cathodic surface, (d) at least one nitrilocarboxylic acid compound having the formula Y 2 N(ZÀYNÀ) n (CH 2 ) m COOM wherein Y is hydrogen, -(CH 2 ) m COOM, -(CH 2 ) m+1 OH or C 1 -C 20 alkyl, Z is a divalent C 2 -C 6 hydrocarbon radical, M is hydrogen, alkali metal or ammonium, m is 1 or 2, n is 0, 1, 2, 3 or 4 and at least one Y is -(CH 2 ) m COOM or -(CH 2 ) m+1 OH, "Quaternary ammonium" includes piperidiniums, pyrrolidiniums and morpholiniums. The conductive salt may itself be a quarternary ammonium salt or may be an alkali metal salt. Specified salts are phosphates, borates, perchlorates, carbonates and sulphates; particularly incompletely substituted salts such as Na 2 HPO 4 and K 2 HBO 3 , and alkali metal and ammonium salts of condensed acids of P and B. Electrolysis may be in a single compartment or diaphragm cell. Specified conditions are: a pH of 2-12; a temperature from the freezing point to 75‹ C. and above; pressures at or above atmospheric; solution flow adjacent the cathode of at least 1 ft./sec.; an anode cathode gap of 40 mils or less to ¢ inch or more; a cathode comprising Cd, Hg, Tl, Pb, Zn, Mn, Sn or graphite; an anode comprising Pt, Ru, Ni, Pb, PbO 2 , C steel, alloy steel Fe or magnetite; and the aqueous solution of the electrolysis medium may also contain a dispersed but undissolved organic phase. In all the examples, acrylonitrile is electrolytically hydrodimerized in undivided cells to form adiponitrile. The aqueous solution contains ethyl tributyl ammonium cations, incompletely substituted sodium orthophosphates, (borates in Examples IV, VII and VIII), and tetrasodium ethylenediamine tetracetate. The anodes are of carbon steel and the cathodes are of Cd except for Example VI where the cathode is Pb.