| 摘要 |
<p>Parent patent describes prepn. of p-benzoquinone diketals of formula (I) (where R is H, 1-4C alkyl or halogen by anodic oxidn. of benzene or anisole substd. in 0- or m-posn. by 1-4C alkyl or halogen. Electrochemical process takes place in MeOH contg. 5 wt.% water and 0.2-15 wt.%, w.r.t. electrolyte, of >=1 of NH4- or alkali fluoride, -perchlorate, -nitrite, -tetrafluoborate, -hexafluorosilicate, -hexafluorophosphate or p-toluene sulphonate, as conductive salt, and opt. of 0.5-10 wt.% base oxidised with a difficulty. Anodic oxidn. takes place at pH 7-10, using a graphite, Pt gp. metal or alloy or PbO2 anode, at -20 to +60 degrees C. In this addn. further conductive salts, opt. replacing those of parent patent, are used. Salts consist of >=1 alkali- and/or ammnium benzene sulphonate and/or >=1 quaternary ammonium- and/or phosphonium salt having formula AxB4-xZ+Y- (where A is 1-4C alkyl; B is Ph; x is integer 1-4; Z is N or P and Y is F or SO4Me). Quat. ammonium- and phosphonium cpds. have higher solubility than conductive salts of Parent Patent. They can be used in up to 30 wt. % concn., w.r.t. electrolyte. An example describes prepn. of p-benzoquinone tetramethyl diketal by electrolysis of benzene. Electrolyte contained NMe4F and MeOH.</p> |
