Non-carbonated overbased magnesium salts prepn. - from hydrocarbyl-substd. hydroxylic aromatic carboxylic acid, useful as additives for lubricants and fuels

摘要

Prepn. of overbased Mg salts with an Mg:acid equiv. ratio of 1.5:5.0:1 comprises reacting a hydrocarbyl-substd. hydroxylic aromatic carboxylic acid (I), or its salts or saponifiable derivs., with a stoichiometric excess (=5 equivs.) of an Mg base (oxide, hydroxide or alcoholate) in the presence of >=0.1 (pref. 0.1-10) ole of H2O per equiv. of Mg base at >=25 degrees C, and then refluxing the mixt. for >=0.5 hr. Proviso is that the reaction is effected in the absence of significant amts. of inorganic acids and carboxylic acids other than (I). Specifically, the hydrocarbyl substituent in (I) contains =10 wt. % of polar gps. selected from SH, halogen, NO2, NH2, NO, SO3H, keto and oxo. The prods. are useful as dispersant, detergent and/or antioxidant additives for lubricant's of fuels (esp. for lubricants used in railway diesel engines). They are also stated to be useful as stabilisers for polymers, e.g. PVC. The process obviates the need to use inorganic acids (e.g. CO2) or promoters (e.g. alcohols or phenols).