| 摘要 |
1,208,325. Production of dichlorophen. BDH CHEMICALS Ltd. 15 April, 1969 [22 April, 1968], No. 18903/68. Heading C2C. Dichlorophen is continuously produced by permitting p-chlorophenol, an aliphatic watermiscible alcohol and 85-95% sulphuric acid to flow together through at least three refrigerated vessels inter-connected in series and supplying to each of the said vessels formaldehyde in a molar percentage which favours the formation of dichlorophen rather than polymers, the molar percentage of formaldehyde supplied to the first vessel being less than 76%, and maintaining the vessels at a temperature between - 10‹ and + 5‹ C. The aliphatic water-miscible alcohol is, for example, methanol, ethanol or isopropanol. The initial concentration of sulphuric acid is preferably between 90 and 95% and the weight thereof is preferably at least four times that of the p-chlorophenol. An aqueous solution of formaldehyde of 35-40% formaldehyde content may be used and at least one mole of formaldehyde is preferably used for each two moles of p-chlorophenol. The first vessel is optionally half-filled initially with a seed mixture comprising methanol, 93% sulphuric acid and 20% w/v. dichlorophen in suspension at ambient temperature. |
