This invention relates to the reaction products of secondary alkyl amines having alkyl groups in the range of 16 to 40 carbon atoms, and preferably 16 to 24 carbon atoms in a straight chain, with ortho phthalic acid or phthalic anhydride to form amides and/or salts useful as additives for distillate fuel oils, where they may be used in combination with wax crystal modifiers, for controlling the size of wax crystals that form in the oil at low temperatures, and for inhibiting agglomeration of the wax crystals. Various reaction products of long chain amines and dicarboxylic acids are known as fuel oil additives.
U.S. Pat. No. 3,095,286 teaches C.sub.4 to C.sub.30 alkyl phthalamic acids and their salts with C.sub.4 to C.sub.30 primary amines as distillate fuel oil additives to inhibit screen clogging, sedimentation and rust.
U.S. Pat. No. 3,166,387 discloses di-C.sub.10 to C.sub.22 alkyl ammonium salts, including dihydrogenated tallow amine salts, of a non-aromatic carboxylic acid, e.g. aliphatic carboxylic acids, as pour point depressants in distillate fuel oils. These salts may also be used as a synergist for hydrocarbon pour point depressants in distillate fuel oil.
U.S. Pat. Nos. 3,444,082 and 3,544,467 teach di-N,N-C.sub.14 to C.sub.28 alkyl substituted C.sub.14 to C.sub.28 alkenyl succinamic acids as additives for distillate fuel oils, which can be used in combination with ethylene copolymer wax crystal modifiers, such as copolymers of ethylene and vinyl acetate.
U.S. Pat. No. 3,658,493 teaches amides and salts of mono and di-carboxylic acids, which acids may be aliphatic or aryl, with amines including secondary amines, but wherein the amine has a single long chain alkyl group, as distillate fuel oil additives in combination with ethylene copolymeric pour point depressants.
U.S. Pat. No. 3,846,481 teaches di-N-octadecyl amine salts of aromatic monocarboxylic acids, such as benzoic acid, as a pour point depressant additive in distillate fuel oils.
U.S. Pat. No. 3,982,909 teaches salts and/or amides of dicarboxylic acids or its monoester, e.g. salts and amides of dicarboxylic acids such as maleic anhydride and ditallow amine, as middle distillate fuel oil additives or in combination with ethylene backbone pour point depressant or waxy hydrocarbons.
In addition to use in fuel oil compositions as noted above, various reaction products of long chain amines and cyclic dicarboxylic acids are also shown by the following for other uses.
U.S. Pat. No. 2,101,323 discloses N,N-dialkyl phthalamic acids and their alkali and alkali metal salts and wherein at least one of the alkyl groups is C.sub.8 to C.sub.18. The amine salts of the long chain compounds, presumably mono- and dialkyl phthalamic acids are said to show wetting and detergent properties.
U.S. Pat. No. 2,892,778 teaches salts and alkyl esters of N-monoalkyl terephthalamic acid as a blending agent for grease.
U.S. Pat. No. 2,915,464 teaches salts of C.sub.8 to C.sub.18 aliphatic amine and N-monoalkylphthalamic acid containing C.sub.8 to C.sub.18 alkyl groups as lubricating oil additives.
U.S. Pat. No. 2,971,027 teaches N,N'-dialkyl diamides of terephthalic acid as thickening agents for lubricating oil compositions.
U.S. Pat. No. 3,887,754 teaches di-N,N'-C.sub.8 to C.sub.22 alkyl diamides of phthalic, dihydrophthalic and tetrahydrophthalic acids.
An anonymous Research Disclosure 17052 of 1978 describes metal salts derived from phthalic acid and dihydrogenated tallow amine such as a salt of a phthalamic acid useful as lubricant additives.