Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1998-08-31
2000-04-11
Padmanabhan, Sreeni
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568785, 568793, C07C 3714
Patent
active
060490152
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a novel process for the C-alkylation of hydroxylated aromatic compounds having at least one hydrogen atom ortho or para to the hydroxyl group. The invention relates in particular to the preparation of 2,5-di-tert-octyl-hydroquinone.
The synthesis of 2,5-di-tert-octylhydroquinone by reaction between hydroquinone and diisobutylene, and more generally the synthesis of hydroxylated aromatic compounds having at least one hydrogen atom ortho or para to the hydroxyl group, has formed the subject of many reaction condition variants in order to improve the yield.
CS patent No. 111,292 proposes the alkylation of 2-methylhydroquinone, 2-tert-butylhydroquinone and 2-tert-octylhydroquinone by diisobutylene with catalysis by concentrated sulphuric acid in the presence of inert solvents (chloroform) or reactive solvents such as ice-cold acetic acid or excess diisobutylene. The yields listed are of the order of 35%. See also in the same respect J. Pospisil and L. Taimr in Collect. Czech. Chem. Commun. 29 (1964), 381-5.
Patent GB-A-1,469,896 describes a process for the synthesis of a hydroxy-(1,1,3,3-tetramethylbutyl)-benzene by reaction between a hydroxybenzene having one or more hydroxyl groups and being optionally substituted, in particular hydroquinone, and a 2,4,4-trimethylpentene, i.e. one of its .alpha.-diisobutylene and .beta.-diisobutylene isomers, or a mixture of the two, in the presence of highly concentrated sulphuric acid and ethylene glycol. As regards that patent, the expression highly concentrated sulphuric acid means a concentration in water of greater than 90% and preferably of about 95.+-.3%. The yield listed is of the order of 60% starting from hydroquinone.
CS patent 273,290 proposes to prepare 2,5-bis-(1,1,3,3-tetramethylbutyl)hydroquinone by alkylation of hydroquinone by diisobutylene with sulphuric acid as catalyst, in a mixture of methanol and aliphatic hydrocarbons. The yield listed is of the order of 65%.
Lastly, patent U.S. Pat. No. 3,373,210 proposes to carry out the alkylation reaction in the presence of methanol and with sulphuric acid as catalyst, for a listed yield of 25%.
In practice, it often turns out to be difficult to obtain the yields listed in these documents. In addition, non-negligible polymerization problems are encountered.
There is thus still a need for a synthetic process which leads simply and reproducibly to advantageous yields, and which furthermore minimizes the risks of polymerization.
The object of the invention is to propose such a process.
The subject of the present invention is thus a process for the C-alkylation of a hydroxylated aromatic compound having at least one hydrogen atom ortho or para to the hydroxyl group, in which process this aromatic compound is placed in the presence of a strong protonic acid and of a compound leading to the formation of a carbocation in the presence of the acid, the reaction being carried out in the presence of a solvent formed of a water/alcohol couple.
The term "aromatic" is taken here in its classical notion as defined in the book by Jerry March, Advanced Organic Chemistry, 4th Edition, published by John Wiley & Sons, 1992.
The starting aromatic compound will be referred to hereinbelow as hydroxybenzene. It can in particular have the formula: ##STR1## in which n=0 to 4, in particular 0 or 1, preferably 1 alkyl, which can optionally have one or more hetero atoms (Cl, Br, O, N, etc.) for example CF.sub.3, O, etc.), the alkyl corresponding to the above definition, for example an alkoxy group, in particular a C1 to C4 and preferably a C1 to C2 alkoxy, for example also methylsulphide or dimethylamine,
They can also be compounds with a heteroaromatic ring, for example hydroxypyridine, or bicyclic aromatic compounds.
In particular, in the case of formula (1), 2 groups R placed on 2 adjacent carbon atoms can form, together with the carbon atoms which bear them, 1 optionally substituted aromatic ring.
The expression formation of carbocation should be understood to mean the formation of carbocation with or wit
REFERENCES:
patent: 3373210 (1968-03-01), Nishio et al.
patent: 4461916 (1984-07-01), Alfs et al.
Chemical Abstracts, vol. 62, No. 6, Mar. 15, 1965, Columbus, Ohio, Abstract No. 6434a, col. 6434, XP002008358.
Collection of Czechoslovak Chemical Communications, vol. 29, No. 2, Feb. 1964, Prague, CS, pp. 381-389, XP002008357, J. Pospisil et al, "Alkylierung von Hydrochinon mit Isobutylen und Diisobutylen".
Chemical Abstracts, vol. 119, No. 13, Sep. 27, 1993, Columbus, Ohio, Abstract No. 138864s, p. 838; XP002008359.
Collection of Dzechoslovak Chemical Communications, vol. 31, No. 1, 1966, Prague, CS, pp. 98-105, XP002024507, J. Popisil et al, Antioxydantien und Stabilisatoren X. Bermerkung zur Darstellung einiger Hydrochinon-alkylderivate.
Journal of the American Chemical Society, vol. 64, No. 4, Apr. 1942, Washington, D.C. pp. 937-940, P002024508, P.F. Oesper et al, "The reduction of dipole moment by steric hindrance in di-t-butylhydroquinone and its dimethyl ether".
Collection of Czechoslovak Chemical Communications, vol. 34, No. 7, 1969, Prague CS, pp. 1991-2001, XP002024509, I. Buben et al, "Oxidation of pyrocatechol. VII. Oxidation of 4-tert-alkylpryocatechols and 2-tert-alkylhydroquinones by oxygen in an alkaline medium".
Collection of Czechoslovak Chemical Communications, vol. 30, No. 4, 1965, Prague, CS pp. 1092-1103, XP002024510, J. Popisil et al, "Antioxydantien und Stabilisatoren V. Darstellung von tert-Butyl-und tert-Octylderiaten des Brenzcatechins", see p. 1100-1103, table l.
Chemical Abstracts, vol. 117, No. 9, Aug. 31, 1992, Columbus, Ohio, Abstract No. 89901z, S.D. Kim et al, "A study on the tert-butylation of hydroquinone", see p. 743, XP002024511, see abstract & Hwahak Koghak, vol. 30, No. 1, 1992, pp. 18-25.
Chemical Abstracts, vol. 67, No. 5, Jul. 31, 1967, Columbus, Ohio. Abstract No. 21664, p. 2049, XP002024512, see abstract & * CS 119 828 A (J. Popisil et al).
Cruciani Paul
Desmurs Jean-Roger
Dury Michel
Serrano Cecile
Padmanabhan Sreeni
Rhodia Chimie
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