Described are multi-ring antioxidant products comprising at least one sulfur-bridged aromatic hydrocarbon compound substituted on at least one of its aromatic rings by at least one sterically hindered 3,5-dihydrocarbyl-4-hydroxybenzyl moiety. Such products have the formula:
R—S.sub.n—R[—S—R].sub.m
wherein each R is, independently, an aromatic hydrocarbon group having 6-12 carbon atoms, wherein m is 0-20, wherein n is 1-6 when m is 0, and when n is 1, m is 1-20; and wherein at least one of R, R.sup.1, and R.sup.2 is substituted by at least one such sterically hindered moiety. The preparation of such products and their use as antioxidants in compositions normally susceptible to oxidative degradation in oxygen or air, e.g., liquid fuel and lubricants, are also described.

A composition comprising a fuel and at least one compound characterized by Formula I:

##STR00001##

wherein X is carbon, oxygen, or sulfur; R.sup.1 and R.sup.2 each independently are hydrogen, a C.sub.1 to C.sub.20 alkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.3 and R.sup.3 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; R.sup.4 and R.sup.4 each independently are hydrogen, a C.sub.1 to C.sub.4 alkyl, a C.sub.4 to C.sub.10 cycloalkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.5 and R.sup.5 each independently are a C.sub.4 to C.sub.10 alkyl; R.sup.6 and R.sup.6 each independently are hydrogen or a C.sub.1 to C.sub.6 alkyl; and R.sup.7 and R.sup.7 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; and wherein the compound of Formula I when subjected to GC-MS using electron ionization at greater than about 70 eV produces at least one ion having a mass-to-charge ratio of from 300 to 600.

A composition comprising a fuel and at least one compound characterized by Formula I: ##STR00001##
wherein X is carbon, oxygen, or sulfur; R.sup.1 and R.sup.2 each independently are hydrogen, a C.sub.1 to C.sub.20 alkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.3 and R.sup.3 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; R.sup.4 and R.sup.4 each independently are hydrogen, a C.sub.1 to C.sub.4 alkyl, a C.sub.4 to C.sub.10 cycloalkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.5 and R.sup.5 each independently are a C.sub.4 to C.sub.10 alkyl; R.sup.6 and R.sup.6 each independently are hydrogen or a C.sub.1 to C.sub.6 alkyl; and R.sup.7 and R.sup.7 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; and wherein the compound of Formula I when subjected to GC-MS using electron ionization at greater than about 70 eV produces at least one ion having a mass-to-charge ratio of from 300 to 600.

A synergistic mixture comprising from 1 to 99.9% by weight of compounds having structural elements (I) ##STR00001##
in which the free valencies on the oxygen atom and on the nitrogen atom may be combined to form a five-, six- or seven-membered ring and the benzene ring may also bear substituents at one or more of the free positions, and from 0.1 to 99% by weight of sulfur-containing organic compounds with antioxidant action. This synergistic mixture is suitable as a stabilizer for stabilizing inanimate organic material, especially mineral oil products and fuels, against the action of light, oxygen and heat.

A method of forming a composition comprising contacting a fuel and at least one compound of Formula I: ##STR00001##
wherein X is carbon, oxygen, or sulfur; R.sup.1 and R.sup.2 each independently are hydrogen, a C.sub.1 to C.sub.20 alkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.3 and R.sup.3 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; R.sup.4 and R.sup.4 each independently are hydrogen, a C.sub.1 to C.sub.4 alkyl, a C.sub.4 to C.sub.10 cycloalkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.5 and R.sup.5 each independently are a C.sub.4 to C.sub.10 alkyl; R.sup.6 and R.sup.6 each independently are hydrogen or a C.sub.1 to C.sub.6 alkyl; and R.sup.7 and R.sup.7 each independently are hydrogen or C.sub.1 to C.sub.4 alkyl; and wherein the compound of Formula I when subjected to GC-MS using electron ionization at greater than 70 eV produces at least one ion having a mass-to-charge ratio of 300 to 600.

A synergistic mixture comprising from 1 to 99.9% by weight of compounds having structural elements (I) ##STR00001##
in which the free valencies on the oxygen atom and on the nitrogen atom may be combined to form a five-, six- or seven-membered ring and the benzene ring may also bear substituents at one or more of the free positions, and from 0.1 to 99% by weight of sulfur-containing organic compounds with antioxidant action. This synergistic mixture is suitable as a stabilizer for stabilizing inanimate organic material, especially mineral oil products and fuels, against the action of light, oxygen and heat.