Europaisches Patentamt European Patent Office © Publication number: 0 363 801 Office europeen des brevets A2 © EUROPEAN PATENT APPLICATION © Application number: 89118396.4 © Int. CI.5: C07C 37/16 , C07C 39/15 © Date of filing: 04.10.89 ® Priority: 14.10.88 US 257981 © Applicant: ETHYL CORPORATION Ethyl Tower 451 Florida Boulevard © Date of publication of application: Baton Rouge Louisiana 70801 (US) 18.04.90 Bulletin 90/16 © Inventor: Livingston, Glen L. © Designated Contracting States: 1220 Watauga Street CH DE FR GB IT LI Kingsport Tennessee 37660(US) Inventor: Borges, John 1211 Austin Street Orangeburg South Carolina 29115(US) Inventor: Mina, George Louis Palmetto Place Apts., Apt. D-3 Orangeburg South Carolina 2911 5(US) © Representative: Dipl.-lng. Schwabe, Dr. Dr. Sandmair, Dr. Marx Stuntzstrasse 16 D-8000 Munchen 80(DE) ® Process for making 3,5-dialkyl-4-hydroxybenzyl-substituted aromatics. © 3,5-di-alkyl-4-hydroxybenzyl-substituted aromat- ics are made in improved yield by co-feeding 2,6-di- alkyl-4-alkoxymethyl phenol and sulfuric acid to a benzene compound, e.g., mesitylene, in an inert solvent at -10 to 50° C. < 00 CO CO CO Q. LU Xerox Copy Centre 1 EP 0 363 801 A2 2 PROCESS FOR MAKING 3,5-DIALKYL-4-HYDROXYBENZYL-SUBSTlTUTED AROMATICS The compound 1,3,5-tri-methyl-2,4,6-tri-(3,5-di- ymethyl group. The most preferred phenol reactant tertbutyl-4-hydroxybenzyl) mesitylene is a commer- is 2,6-di-tert-butyl-4-methoxymethyl phenol. cial antioxidant (Ethanox® 330, product of Ethyl The aromatic compound can be any aromatic Corporation). This compound and a method of pre- benzene compound having an unsubstituted nu- paring it by reacting 3,5-di-tert-butyl-4-hydroxyben- 5 clear position capable of substitution. These in- zyl alcohol and mesitylene together with sulfuric clude benzene, naphthalene, phenol, p-cresol, acid or a Friedel Crafts catalyst is described in durene, mesitylene and the like. Rocklin et al. U. S. 3,026,264. In a more preferred embodiment, the aromatic Another method for making the above antiox- compound is an alkylbenzene compound such as idant is described in Gurvich et al. GB 1,327,542. 10 toluene, xylene, durene, mesitylene, ethylbenzene According to Gurvich et al., 2,6-di-tert-butyl-4- and the like. The -most preferred aromatic com- methoxymethyl phenol and mesitylene acid are pound is mesitylene. mixed in an inert solvent such as methylene' chlo- The reaction is preferably carried out in an ride and stirred at 1-5° C while adding sulfuric acid. inert solvent. Useful solvents include aliphatic and The present invention is an improvement on 75 cycloaliphatic- hydrocarbons and aliphatic the process described by Gurvich et al. which halohydrocarbons. Examples are hexane, heptane, results in a substantial cost reduction. isooctane, cyclohexane, 1 ,2-dichloroethane, According to the present invention, 3,5-dialkyl- methylene chloride, methylene bromide, 1,1,2-trich- 4-hydroxybenzyl-substituted aromatic compounds loroethane and the like. The preferred solvents are are prepared in increased yield and purity by co- 20 the halohydrocarbons, especially methylene chlo- feeding 2,6-dialkyl-4-alkoxymethyl phenol and sul- ride. furic acid to an aromatic compound, such as durene The amount of solvent should be an amount or mesitylene. The new process not only improves that will serve to dissolve the aromatic compound yield but decreases the amount of 4,4 -alkylene bis and the 2,6-di-alkyl-4-alkoxymethyl phenol at reac- (2,6-dialkylphenol) formed in the process. Such 25 tion temperature. A useful range when reacting 2,6- bisphenols are effective antioxidants in their own di-tert-butyl-4-methoxymethyl phenol with right but are undesirable in the 3,5-di-alkyl-4- mesitylene using a methylene chloride solvent is hydroxybenzyl-substituted arqmatics made' by the 150-500 parts by weight and more preferably 200- present invention. 300 parts per 100 parts of mesitylene and 2,6-di- A preferred embodiment of the invention is a 30 tert-butyl-4-methoxymethyl phenol. Part of the sol- process for making a 3,5-dialkyl-4-hydroxybenzyl- vent may be charged to the reactor to dissolve substituted aromatic compound, said process com- mesitylene and part mixed with 2,6-di-tert-butyl-4- prising co-feeding (i) a 2,6-dialkyl-4-alkoxymethyl methoxymethyl phenol. phenol and (ii) sulfuric acid to an aromatic com- The ratio of 2,6-di-alkyl-4-alkoxymethyl phenol pound selected from benzene or an alkyl-substi- 35 to aromatic compound should be at least one mole tuted benzene. per equivalent of substituent positions in the ar- The 2,6-dialkyl-4-alkoxymethyl phenols include omatic compound. For example, one mole of any such compound wherein the alkyl groups con- durene has two equivalents of open nuclear posi- tain 1 to 20 or more carbon atoms. A few repre- tions and one mole of mesitylene has three equiv- sentative examples are: 2,6-di-methyl-4-methox- 40 alents of unsubstituted substituent positions. ymethyl phenol; 2,6-di-ethyl-4-ethoxymethyl phe- In a preferred embodiment 2.0-2.75 moles and nol; 2-methyl-6-ethyl-4-propoxymethyl phenol; 2,6- more preferably 2.1-2.3 moles of 2,6-di-tert-butyl-4- di-sec-butyl-4-methoxymethyl phenol; 2,6-di- methoxymethyl phenol would be used per mole of isopropyl-4-methoxymethyl phenol; 2-methyl-6-tert- durene. butyl-4-methoxymethyl phenol; 2-methyl-6-sec- 45 In another preferred embodiment 3.0-4.0 moles dodecyl-4-butoxymethyl phenol; 2,6-di-sec-eicosyl- and more preferably 3.25-3.75 moles of 2,6-di-tert- 4-dodecyloxymethyl phenol; 2,6-di-tert-octyl-4- butyl-4-methoxymethyl phenol would be used per methoxymethyl phenol and the like. mole of mesitylene. In a more preferred embodiment, at least one The sulfuric acid should be fairly concentrated. of the 2,6-dialkyl groups is a tert-alkyl group. In a so A useful concentration is 70-100 weight percent highly preferred embodiment the alkyl group in the H2SO4. In a more preferred embodiment 75-98 alkoxymethyl group is a lower alkyl group contain- weight percent H2SO4. is used. In a most preferred ing 1-4 carbon atoms. In a still- more preferred embodiment the sulfuric acid is 80-90 weight per- embodiment both alkyls in the dialkyl groups are cent H2SO+. tert-alkyls and the alkoxymethyl group is a methox- The amount of sulfuric acid should be an 2 3 EP 0 363 801 A2 4 amount which causes the reaction to go substan- A useful reaction temperature range is -10° C up to tially to completion. A useful range in which to 50 °C. More preferably the reaction is conducted at ° ° experiment is 1 -1 00 percent based on the weight of -5 C up to 25 C. the 2,6-dialkyl-4-alkoxymethyl phenol reactant. In a The manner of carrying out the co-feed pro- preferred embodiment the amount of H2SO4 in the 5 cess is shown in the following example. sulfuric acid is 0.5-0.8 parts by weight per part of 2,6-dialkyl-4-alkoxymethyl phenol. The important feature of the invention is that at Example least a part of the 2,6-di-alkyl-4-alkoxymethyl phe- nol and sulfuric acid are simultaneously co-fed to 70 the aromatic compound. In the prior art the 2,6- In a first stage, a reaction vessel was charged dialkyl-4-alkoxymethyl phenol and aromatic com- with 4.0 Kg of methylene chloride, 1.17 Kg (9.75 pound were mixed in the reactor together with a moles) of mesitylene and 13.65 Kg of 32.9 weight solvent and the sulfuric acid fed to this stirred percent solution of 2,6-di-tert-butyl-4- mixture. In the present process the aromatic com- 75 methoxymethyl phenol (17.96 moles) in methylene pound, e.g., mesitylene, and solvent, e.g., chloride containing about 2.7 weight percent of methylene chloride, are placed in the reactor. The other phenolic impurities. This solution was cooled 2,6-dialkyl-4-alkoxymethyl phenol which may op- to 5°C and while stirring, 3.8 Kg of an 84 weight tionally contain inert solvent and the sulfuric acid percent HaSO* was slowly added. The mixture was are concurrently fed to the reaction mixture over an 20 then stirred for 30 minutes at 6-7° C. extended period. The feed of each may be continu- ous or in increments during the course of the reaction. The rate of feed of each can vary but as a Co-Feed Stage guide it is preferred that each feed rate is such that the feed of each is completed at about the same 25 time. Following the first stage an additional 4.0 Kg of In a preferred embodiment, it has been found methylene chloride was added. The two streams that it is not necessary to co-feed all of the- 2,6- were co-fed to the stirred reaction mixture held at dialkyl-4-alkoxyalkyl phenol ("phenolic") and sulfu- 5-7° C. One stream was 13.65 Kg of the 32.9 ric acid. Good results have been achieved by con- 30 weight percent solution of 2,6-di-tert-butyl-4- ducting the. process in two stages. The first stage methoxymethyl phenol (17.96 moles) in methylene is conducted in a conventional manner except only chloride and the other was 4.4 Kg of 84 weight part of the total phenolic and sulfuric acid are used. percent H2SO+. The first stream was fed at about In the second stage called the "co-feed stage" the 95 g/min (143.7 min.) and the H2SO4.