Patent GB-688704-A (GB)
Title: Improvements in and relating to the stabilisation of organic compounds
Inventor: COWIE CHARLES THOMSON YOUNG
IPC: C09K15/08
Filed: 1950-05-25
Abstract: Organic compounds, other than formaldehyde, liable to deterioration arising from peroxide formation are stabilized by incorporating a small amount of a 2,3,5,6-tetra-alkylated phenol of formula <FORM:0688704/IV (b)/1> wherein R2 and R3 are methyl or ethyl, R1 is an alkyl group having at least 3 C atoms, and at least one H atom attached to the carbon atom adjacent to the benzene ring, and R4 is an alkyl group.  Preferably 0.001-1 per cent of phenol is used and R1 and R4 contain not more than 8 C atoms.  Compounds specified for stabilization are liquid aldehydes, ethers, petrols, animal or vegetable fatty oils, and ester or hydrocarbon lubricating oils.  The phenols may be made by reacting phenols of formula <FORM:0688704/IV (b)/2> or <FORM:0688704/IV (b)/3> with an olefine, an alcohol R1OH or a halide R1X in the presence of an alkylation catalyst at an elevated temperature, usually about 30 DEG  C.  Acidic alkylation catalysts are preferred, e.g. sulphuric and phosphoric acid, boron trifluoride and Friedel-Craft catalysts.  Oleum of 2 per cent in an amount of 5-15 per cent of the phenol is especially suitable.  Propylene, butene-1 and butene-2 are specified olefines, n-propanol, isopropanol, n-butanol and isobutanol are specified alcohols and n-propyl-, isopropyl-, and n-butyl- and isobutyl-chlorides specified halides.  2,6-Di-isopropyl-3,5-dimethyl- and 6-isopropyl-2,3,5-trimethyl-phenols, which are new compounds, are made respectively by reacting gaseous propylene in the presence of oleum with 3,5-dimethyl phenol at 70 DEG  C. or 2,3,5-trimethyl phenol at 110-120 DEG  C.  The benzoates of both phenols are described and the former is converted to 3,5-di-isopropyl-2,6-dimethyl-4-hydroxy-41-nitro-azobenzene, and 2,6-di - isopropyl - 3,5 - dimethyl - 1,4 - benzoquinone and -hydroquinone, the dibenzoate of the latter compound being obtained. 3-Methyl-5-ethyl-phenol is also specified for alkylation.  In examples: (1) nonaldehyde and (2) thermally cracked petrol are stabilized with the above two new phenols.  The Provisional Specification includes 2,3,5-trialkylated phenols and the various R1s are any alkyl groups except that the R in the 2-position has at least 3 C atoms and has at least one H atom attached to the C atoms adjacent the benzene ring.ALSO:3,5 - Di - isopropyl - 2,6 - dimethyl - 4 - hydroxy - 41 - nitro - azobenzene is made by reacting 2,6 - di - isopropyl - 3,5 - dimethyl phenol with diazotized p-nitraniline in acetic acid solution.ALSO:Petrols and lubricating oils, e.g. hydrocarbon or ester lubricating oils, liable to deterioration by peroxide formation, are stabilized by incorporating a small amount of a phenol of formula <FORM:0688704/III/1> wherein R2 and R3 are methyl or ethyl, R1 is an alkyl group having at least 3 C atoms, and at least one H atom attached to the C atom adjacent to the benzene ring, and R4 is an alkyl group.  Preferably 0.001-1 per cent of phenol is used and R1 and R4 contain not more than 8 C atoms. 2, 6-di isopropyl-3, 5 dimethyl- and 6-iso-propyl-2, 3, 5-trimethyl-phenols are specified.  In Example 2 thermally cracked petrol is stabilized with 0.04 per cent of each of the above specified phenols.