Disclosed is a process for preparing a diaryl oxalate which comprises the step of transesterifying a dialkyl oxalate or/and an alkylaryl oxalate with an aryl alcohol in the presence of a tetra(aryloxy)titanium as a catalyst, wherein the tetra(aryloxy)titanium is fed into a reaction system of the transesterification as an aryl alcohol solution of the tetra(aryloxy)titanium which is prepared by reacting a tetraalkoxy titanium and an excess amount of the aryl alcohol and removing a by-producing alkyl alcohol.
A catalyst composed of an organic phosphorus compound having a trivalent or pentavalent phosphorus atom and at least one carbon-phosphorus bonding or a combination of the organic phosphorus compound and a halogen atom-containing compound is effective for decarbonylation, that is, for releasing carbon monoxide from a compound containing a moiety of -CO-CO-O- in its molecular structure.
Quaternary aryl phosphonium salts as corrosion inhibitors for iron in HCl
作者:A.H. Nahlé、T.J. Harvey、F.C. Walsh
DOI:10.1016/j.jallcom.2018.06.241
日期:2018.10
inhibition of iron in deaerated 1 M HCl at 22 °C are obtained for five synthesized phosphonium salts, 4-tolyltriphenyl-phosphonium chloride (TTPPC), 4-phenoltriphenylphosphonium chloride (PTPPC), 4-anilinetriphenylphosphonium bromide (ATPPB), 4-benzyl alcoholtriphenylphosphonium chloride (BATPPC), 4-hlorophenyltriphenylphosphonium bromide (CPTPPB), and two commercially available phosphonium salts, tetraphenylphosphonium
A diaryl carbonate is prepared at a high yield and a high selectivity by heating a diaryl oxalate in the presence of an organic phosphorous compound to release carbon monoxide therefrom. A halogen atom-containing compound can be employed in combination with the organic phosphorous compound.
A diaryl carbonate with a high degree of purity is produced at a high yield by (A) subjecting (a) a diaryl oxalate and a phenol compound or (b) an alkylaryl oxalate to transesterification reaction in one or two stages in the presence of a catalyst to prepare a diaryl oxalate, while removing a by-product from the reaction system; (B) collecting the diaryl oxalate from the resultant reaction product mixture of the step (A); (C) subjecting the diaryl oxalate to a decarbonylation reaction, preferably in the presence of a phosphorous compound-containing catalyst, to convert the diaryl oxalate to a corresponding diaryl carbonate, while removing a reaction by-product comprising carbon monoxide from the reaction system; and (D) collecting the diaryl carbonate from the reaction product mixture of the step (C).