申请人:Bayer Aktiengesellschaft
公开号:US04276431A1
公开(公告)日:1981-06-30
Alkali metal salts of hydroxybenzoates are claimed which are substantially anhydrous and free from hydrobenzoic acid and have the formula ##STR1## in which R.sup.1 denotes alkyl, alkenyl, cycloalkyl or aralkyl, R.sup.2 and R.sup.3 are identical or different and represent hydrogen, halogen, hydroxyl, amino, alkylamino, alkyl, alkoxy, aralkyl or aryl and Me denotes an alkali metal. Furthermore a process for the preparation of the said alkali metal salts of hydroxybenzoates, which are substantially anhydrous and free from hydrobenzoic acid, characterized in that a solution or suspension of a hydroxybenzoate of the formula ##STR2## in which R.sup.1, R.sup.2 and R.sup.3 have the abovementioned meaning, is neutralized with an alkali metal hydroxide at -10.degree. to +50.degree. C. until the degree of neutralization is 0.95 to 1.05, a degree of neutralization of 1.00 denoting the end point of the neutralization of the phenolic OH group by the alkali metal hydroxide, and the resulting solution or suspension of the alkali metal salt of the hydroxybenzoate is passed to a mild drying operation which does not damage the product and is in itself known, after a time such that the content of hydroxybenzoic acid or the alkali metal salt thereof in this solution or suspension does not reach the value of 1% by weight, relative to the amount of alkali metal salt of hydroxybenzoate contained in this solution or suspension.
本发明涉及疏水基苯羟酸的碱金属盐,其基本无水且不含羟基苯甲酸,其化学式为##STR1## 其中R1表示烷基、烯基、环烷基或芳基烷基,R2和R3相同或不同,表示氢、卤素、羟基、氨基、烷基氨基、烷基、烷氧基、芳基烷基或芳基,Me表示碱金属。此外,本发明还涉及一种制备基本无水且不含羟基苯甲酸的碱金属盐的方法,其特征在于,在-10℃至+50℃的条件下,用碱金属氢氧化物中和式##STR2## 其中R1、R2和R3具有上述含义,直至中和度为0.95至1.05的溶液或悬浮液,中和度为1.00表示碱金属氢氧化物中和酚羟基的终点。将所得的碱金属盐的溶液或悬浮液经过适量的干燥操作,该操作不会损坏产品且已知。在此之后的一段时间内,使得该溶液或悬浮液中的羟基苯甲酸或其碱金属盐的含量不超过1重量%,相对于该溶液或悬浮液中所含的羟基苯甲酸盐的量。