Patent GB-828910-A (GB)
Title: Antioxidant compositions
IPC: C10L1/30
Filed: 1956-03-21
Abstract: The tendency of tetra-alkyl lead anti-knock compounds, liquid hydrocarbon fuels, or nonfluid petroleum hydrocarbon compositions, to deteriorate in the presence of oxygen, air, or ozone, is inhibited by the addition of a minor proportion of a 2,6-dialkyl phenol of formula <FORM:0828910/III/1> wherein R is methyl, ethyl, C3-C12 secondary alkyl or C4-C12 tertiary alkyl and R1 is C4-C12 tertiary alkyl.  The phenol may be added to anti-knock compositions (suitable, for example, for adding to gasoline), containing such tetra-alkyl lead compounds as tetramethyl lead, tetraethyl lead, tetrapropyl lead, dimethyl diethyl lead, trimethyl ethyl lead and mixtures thereof. Such compositions may also contain dyes, metal deactivators, diluents and halogencontaining scavengers such as chlorinated and/or brominated hydrocarbons or ethers.  Where the 2,6-dialkyl phenol employed in the antiknock composition is 2,6-di-tert.-butyl phenol, this may be used in conjunction with N,N1-disec.-butyl-p-phenylene diamine or 4-(isopropylamino)-diphenylamine, the weight ratio of the diamine to 2,6-di-tert.-butyl-phenol being from about 9 to 1 to about 1 to 9.  Many examples are given of tetra-alkyl lead compositions containing 2,6-di-tert.-butyl-phenol, 2-tert.-butyl-6-(2-decyl)-phenol, 2-methyl-6-tert.-butyl-phenol, 2-methyl-6-tert.-amyl-phenol, 2-ethyl-6-tert.-butyl-phenol or 2-isopropyl-6-tert.-butylphenol, with or without halogen-containing scavengers.  The non-fluid petroleum hydrocarbon compositions may be petroleum wax compositions or lubricating greases, and the latter may consist essentially of mineral lubricating oil and a metallic soap thickening agent derived from fats, fatty acids, woolgrease, rosin or naphthenic acids.  The mineral lubricating oil may be used in conjunction with synthetic oils, while the soap thickening agent may be used in conjunction with other thickeners such as silica gel, carbon black and clays, such as bentonite treated with quaternary ammonium compounds or attapulgus clay treated with surface-active agents.  Synthetic oils mentioned are oils derived from coal, alkylene oxide polymers and esters, such as esters of alkylene oxide polymers, dicarboxylic acid esters, polyesters, esters of polyhydric alcohols and esters of acids of phosphorus and silicon. The greases may contain additional ingredients such as monohydric and polyhydric alcohols (e.g. glycerol), alkaline substances (e.g. excess alkali), moisture and fillers.  In examples: (a) 2-methyl-6-tert.-butyl-phenol is added to microcrystalline wax or to a grease prepared from mineral lubricating oil, lithium hydroxide, palm oil, hydrogenated fish oil fatty acids, naphthenic acid and acetic acid; (b) 2,6-di-tert.-butyl-phenol is added to an N.L.G.I. No. 2 grease containing lithium soap, or to a lubricating grease prepared from mineral lubricating oil, lime, 12-hydroxy-stearic acid and boric acid, or to a lubricating grease prepared from mineral lubricating oil, aluminium stearate and lithium stearate; (c) 2,6-di-tert.-amyl-phenol is added to a lubricating grease prepared from mineral lubricating oil, lime, stearic acid, partially hydrogenated castor oil and hydracrylic acid, and (d) 2-ethyl-6-tert.-butyl-phenol is added to a lubricating grease prepared from mineral lubricating oil, barium petroleum sulphonate, ethane sulphonic acid and barium hydroxide.ALSO:2,6-Dialkyl phenols of formula <FORM:0828910/IV (b)/1> wherein R is methyl, ethyl, C3-C12 secondary alkyl or C4-C12 tertiary alkyl and R1 is C4-C12 tertiary alkyl, are employed as antioxidants for tetra-alkyl lead anti-knock compounds, liquid hydrocarbon fuels and non-fluid petroleum hydrocarbon compositions (see Group p  III).  These dialkyl phenols may be prepared by alkylation of a phenol with an olefin in the presence of an aluminium phenoxide catalyst.  Thus, 2-methyl-6-t-amyl-phenol may be prepared by alkylating o-cresol with 2-methylbutene-1 in the presence of aluminium o-cresolate, while 2-isopropyl-6-t-butyl-phenol may be prepared by alkylating phenol first with propylene and then with isobutylene in the presence of aluminium phenoxide.ALSO:The tendency of solid hydrocarbon polymers which have a molecular weight of at least 10,000 and which may contain small amounts of nitrogen or sulphur to deteriorate in the presence of oxygen, air, or ozone, is inhibited by the addition of a minor proportion of a 2,6-dialkylphenol of formula <FORM:0828910/IV (a)/1> wherein R is methyl, ethyl, C3-C12 secondary alkyl or C4-C12 tertiary alkyl and R1 is C4-C12 tertiary alkyl.  Polymers mentioned are natural rubber (whether vulcanized or not), GR-S and GR-N rubbers, butyl rubber, methyl rubber, polybutene rubber, butadiene rubbers, piperylene rubbers, dimethyl-butadiene rubbers, polystyrene, polybutadiene, polyisobutylene, polyethylene and isobutylene-styrene copolymer.  In examples, 2,6-di-tert.-butyl phenol is added to (a) a synthetic rubber mix consisting of GR-S rubber, zinc propionate, zinc stearate, carbon black, road tar, sulphur and mercaptobenzothiazole, (b) a synthetic rubber mix consisting of GR-N rubber, zinc stearate, carbon black, road tar, sulphur and mercaptobenzothiazole, (c) a natural rubber mix consisting of smoked sheets, carbon black, zinc oxide, stearic acid, pine tar oil, sulphur and mercapto benzothiazole, (d) a natural rubber mix consisting of pale crepe rubber, zinc oxide, titanium dioxide, stearic acid ultramarine blue, sulphur and mercaptobenzothiazole, (e) polyethylene or (f) polystyrene; 2-methyl-6-tert-butyl phenol is added to (a), (c), (e) or (g) polybutadiene; 2-isopropyl-6-tert.-butyl phenol is added to (h) a synthetic rubber mix similar to (a) but containing no zinc propionate or to (i) polyisobutylene; 2-methyl-6-tert.-amyl phenol is added to (f); 2-ethyl-6-tert.-butyl phenol is added to (j) butyl rubber; and 2,6-di-tert.-amyl phenol is added to (k) natural rubber.