Process for the preparation of substituted aromatic compound...

Details Process for the preparation of substituted aromatic compound... Process for the preparation of substituted aromatic compound...

2000-10-10

2003-04-15

Padmanabhan, Sreeni (Department: 1621)

Chemistry of hydrocarbon compounds

Aromatic compound synthesis

By condensation of entire molecules or entire hydrocarbyl...

C568S332000, C568S628000, C568S734000, C568S928000

Reexamination Certificate

active

06548722

ABSTRACT:

FIELD OF THE INVENTION
A process for the preparation of substituted aromatic compounds employing Friedel-Crafts reaction and using a basic anionic clay hydrotalcite-type solid catalyst. This invention particularly relates to a process for the alkylation or acylation of aromatic compounds by an alkylating or acylating agent for preparing alkylated or acylated aromatic compounds, using basic anionic clay hydrotalcite-type solid catalyst.
BACKGROUND AND PRIOR ART REFERENCES
The process for this invention could be used for the preparation of alkylated or acylated aromatic compounds, which are fine chemicals and/or used as intermediates in the preparation of fine chemicals or specialty chemicals in dyes and pharmaceutical industries and other chemical industries.
Both the homogeneous and heterogeneous catalyzed liquid phase Friedel-Crafts processes for the preparation of alkylated and acylated aromatic compounds are known in the prior art.
Friedel-Crafts Type Reactions Catalysed by Homogeneous Acid Catalysts
The Friedel-Crafts type reactions, such as alkylation and acylation of aromatic compounds by various alkylating or acylating agents, using homogeneous Lewis acid catalysts, such as AlCI
3
, BF
3
, ZnCl
2
and other metal chlorides and protonic acid catalysts, such as H
2
SO
4
, H
3
PO
4
, HF, etc., are well known in the prior art [ref. G. A. Olah, in Friedel-Crafts and related reactions: vol. Ill, Acylation and related reactions, Wiley-Interscience Publ., New York, 1964].
A use of CuCl
2
as a homogeneous catalyst in the benzylation of benzene or substituted benzenes by benzyl chloride is disclosed in two US patents: U.S. Pat. No. 3,678,122(1972) and U.S. Pat. No. 3,679,760(1972). A French patent, FR 2,144,578(1973), disclosed benzylation of p-substituted phenols by benzyl halides in the presence of homogeneous ZnCl
2
catalyst. A USSR patent, U.S. Ser. No. 394,353(1973), disclosed a use of SnSO
4
or SnCl
2
as homogeneous catalyst for the benzylation with benzyl chloride of m-dimethoxy benzene. A Japanese patent, JP 7399,154(1973), disclosed preparation of dibenzyl benzene derivatives by benzylation of benzene or substituted benzenes using AlC
3
, FeCl
3
and 98% H
2
SO
4
. A use of H
2
SO
4
or H
3
PO
4
and optionally 4-CH
3
C
6
H
4
SO
3
H, ZnCl
2
, BF
3
, ect. in the preparation of o-benzyltoluenes by the reaction of &agr; o-chloromethyltoluene with a benzene derivative is disclosed in a German patent, Ger. Offen 2,456,747 (1976). A use of phosphoric acid and optionally H
2
SO
4
or a Friedel-Crafts type metal halide in the benzylation of benzene with benzylether is disclosed in a US Patent, U.S. Pat. No. 4,049,733 (1977).
A German patent, Ger. offen 2,451,037 (1976), disclosed the use of HF as a catalyst for the benzoylation of aromatic compounds.
A French patent, FR 2,496,097 (1982) disclosed the acylation of benzene by phthalic anhydride using HF—BF
3
mixture.
More recently, an European Patent, EP 53.8,704 (1993), disclosed a process for the preparation of p-substituted o-benzylphenols by treating phenols, p—R C
6
H
4
OH (R=halo, alkyl, OH, alkoxy, alkylmercapto, aryl, aryloxy or arylmercapto), with ArCH
2
X (Ar=corresponding aryl nucleus; X=halo, arylcarboxy, phenylsulfatoxy, hydroxy, alkoxy etc.) in a continuously functioning distillation apparatus in the presence of dissolved acid catalyst.
The main disadvantages of the Friedel-Crafts processes based on the use of homogeneous acid catalyst are as follows:
1) The separation and recovery of the dissolved acid catalysts from the liquid reaction mixture is difficult.
2) The disposal of the used acid catalysts creates environmental pollution.
3) The homogeneous acid catalysts also pose several other problems such as high toxicity, corrosion, spent acid disposal and use of more than the stoichiometric amount.
Friedel-Crafts Type Reactions Catalysed by Heterogeneous Solid Acid Catalysts
A German patent, Ger.Offen 2,547,030 (1977), disclosed the preparation of o-benzyl toluenes by the reaction of o-methylbenzyl halides with substituted benzenes in the presence of Al-silicate. The 2-CH
3
C
6
H
4
CH
2
Cl was stirred with toluene and Al-silicate (25% Al
2
O
3
) at 110° C. to give 81% 2-methylbenzyltoluene. According to a Japanese patent, JP 59,186,937 (1984), o-benzylphenol was prepared by the liquid phase reaction of benzyl alcohol with phenol in the presence of &ggr;-Al
2
O
3
. For example 7.5 g &ggr;-Al
2
O
3
was added to a mixture of 32.5 g benzyl alcohol and 47 g phenol at 190° C. under stirring to give a product-containing 49.9% o-benzylphenol. A German Patent, Ger. Offen DE 3,700,917 (1988), disclosed the preparation of p-substituted o-benzylphenols by alkylation of p-substituted phenols with benzylalcohol in the presence of Na—Y type zeolite. A mixture of 0.5 mole 4-ClC
6
H
4
OH, 0.1 mole C
6
H
5
CH
2
OH and 0.6 g of Na—Y type zeolite was heated at 200° C. for 3 hrs to give 25.4% 2-benzyl-4-chlorophenol.
A French patent, FR 2,667,063 (1992), disclosed the preparation of 4-substituted benzophenones by acylation of substituted benzenes by substituted benzoic acid in the presence of H&ggr;-and H&bgr; type zeolites. Accordingly, 4-ClC
6
H
4
COOH and PhMe were heated 4 h at 200° C. under 2×10
5
Pa in the presence of calcined zeolite H&bgr; to give 84.4% 4-(4-Cl C
6
H
4
CO)C
6
H
4
Me.
A recent paper by Vincent et al. (ref. Tetrahedron Lett. 35, 1994, 2601), disclosed that H-ZSM-5 zeolite can catalyze the acylation by benzoyl chloride of phenol and anisole but not the acylation with benzoyl chloride of benzene, halobenzene and naphthalene, at 120° C. for 5 h.
A German patent, Ger. Offen DE 3,836,780 (1990), disclosed the process for the preparation of benzylbenzenes from benzenes and benzyl alcohols in the presence of activated bleaching earth and a diluent at 90-140° C. According to Japanese patent, fP 03,170,442 (1991), benzylbiphenyls are manufactured by alkylating biphenyl and diphenylmethane with ≧1 compound from benzyl halides, benzyl alcohol, benzyl ether in the presence of a zeolite or silica-alumina catalyst. An European patent, EP 428,081 (1991), disclosed a process of alkylation of alkylbenzenes with benzyl chloride in the presence of H—Y or H—L zeolite catalyst. A German patent, Ger. Offen DE 4,038,933 (1992), disclosed a process for alkylation of aromatics using technical carbon catalysts.
Alkylation or acylation of aromatic compound involves electrophilic substitution of H from the aromatic nucleus of the aromatic compound. It is well known in the prior art that the electrophilic substitution is favored by the presence of electron donating groups, such as OH, alkyl, alkoxy, phenoxy, amine, alkyl amine, SH, etc., in the aromatic compound. Whereas the electrophilic substitution is inhibited by the presence of electron withdrawing groups such as halo, nitro, cyano, carboxy, aldehyde, etc., in the aromatic compound [ref. G.A.Olah, in Friedel-Crafts and related reactions, Wiley-Interscience Publ, New York, 1963].
Although some limitations of the homogeneous acid catalyzed processes are overcome in the prior art of heterogeneous solid catalyzed processes described above, the alkylating or acylating activity of the solid acid catalysts used in the prior art processes is low, particularly when no electron donating group is present in the aromatic compound, such as benzene, naphthalene and anthracene, to be alkylated or acylated. Both the homogeneous and heterogeneous acid catalysts of the prior art are highly moisture sensitive, and hence demand moisture-free or thoroughly dried reactants, solvents and catalyst for the Friedel-Crafis processes. In presence of moisture in the reaction mixture, both the above homogeneous and heterogeneous catalysts show poor activity in the Friedel-Crafts type processes. Hence there is a great practical need for finding more efficient and also moisture insensitive solid catalyst for the alkylation or acylation of aromatic compounds. There is also a need for finding highly efficient non-acidic or basic solid catalyst for alkylating or

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