Patent ID: 7740668

Claim:
A method for reducing the level of toluene insolubles in aminated unleaded aviation gasoline while retaining good water shedding properties wherein such unleaded aminated aviation gasoline comprises (i) an unleaded aviation gasoline having a base MON of less than 98, and (ii) an amount of at least one aromatic amine effective to boost the motor octane number of the base fuel to at least 98, the aromatic amine having the formula wherein R x is C 1 -C 10 alkyl, a halogen or a mixture thereof, n is an integer from zero to 3 and wherein when n is 1 or 2 and R x is an alkyl group, the alkyl group occupies the meta and/or para position on the phenyl ring, by adding to such aminated unleaded aviation gasoline up to about 1000 wppm of a deposit control additive selected from the group consisting of high molecular weight hydrocarbyl amine, and mixtures of 2-6 ditertbutyl hydroxy toluene (BHT) and N,N disalicylidene-1,2 propane diamine (MDA) wherein the high molecular weight hydrocarbyl group has a weight average molecular weight of about 400-2800 Mw, and optional carrier oil(s), and wherein said unleaded animated aviation gasoline is characterized by toluene insoluble deposits of 0.8 mg or less measured by a test in which a metal nub is cycled between 150° C. and 300° C. in 9 minute cycles while about 40 ml of the aminated unleaded aviation gasoline is dripped on the nub in an air atmosphere, the nub weighed to five decimal places (0.00001 g) before and after the aminated unleaded gasoline aviation gasoline is dripped onto it, the nub then being washed with n-heptane and weighed and with toluene and weighed to determine the toluene insoluble deposits and water shedding properties as determined by MSEP/water shedding test method ASTM D3948 Rev. A setting B using the yellow cell of at least 70.