Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1986-08-14
1988-01-26
Terapane, John F.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568928, C07C 7910
Patent
active
047218215
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method for synthesis of bibenzyl systems with nitro groups as substituents. Such compounds are important intermediates for pharmaceuticals.
According to the method toluene derivates with nitro groups, preferably in o- or p-position, are coupled oxidatively with air (oxygen) in methanolic KOH-solution under influence of small amounts of metal catalysts.
Several methods for the synthesis of nitrobibenzyl systems are known: ##STR1## This method needs handling of KOtBu or NaOEt. The best yield, about 70%, was reached by bubbling oxygen through the reaction mixture. The recovery of the product needs handling of ether and without equivalent amount of iso amyl formiate the yield will come down to 40%. Using NaOMe about 55% is obtained. KOtBu must be used in ether. The reaction time is long, about 24 hours at 0.degree. C. ##STR2## Pure oxygen must be used. The yield is low, about 30%. Ethylene diamine is a catalyst. ##STR3## Yields 51-60%. The reaction time is short but large amounts of liquid ammonia must be used. NaNH.sub.2 is prepared in situ from NH.sub.2. It is a drawback that sodium must be handled.
The earlier methods have several drawbacks as in certain cases bad yields, handling of chemicals with risks for the environment and comparatively expensive raw materials.
SUMMARY OF THE INVENTION
In the method according to the present invention more inexpensive raw materials are used, air is used instead of oxygen and the catalysts are only used in small amounts. The method is superior to earlier methods as to economy as well as to safety.
The synthesis according to the present method can be illustrated as follows: ##STR4## Examples: o-Nitrotoluene, p-nitrotoluene.
As metal catalysts metal acetonylacetonate, Me(AcAc).sub.2, metal acetonylacetonate+crown ether, metal salt+crown ether or metal-tetraphenylporphin (porphyrin type) are used. ##STR5##
In the method inexpensive starting materials, suitable for full-scale production, as o-nitrotoluene, KOH, air and catalytic amounts of metal complex are used. Handling of Na or NaOEt in technical scale is avoided as well as the handling of NaNH.sub.2. Oxygen is replaced by air (but it is possible to use oxygen).
The method will be further illustrated by the following non-limiting examples.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Example 1
Preparation of 2,2'-dinitrobibenzyl
A catalytic amount of a metal catalyst (0.01 g metal porfin or 0.005 g metal (AcAc).sub.2 +0.01 g crown-ether) was added to a 33% methanolic KOH-solution, (34 g KOH in 100 ml methanol). The reaction mixture was cooled to 25.degree. C., 2-nitrotoluene (13.7 g, 0.1 mol) was added and air was passed through the reaction mixture, the temperature of the reaction mixture being kept at 25.degree. C. After 12 hours the passsing through of air was interrupted and 150 ml water and 50 ml methanol was added. The reaction mixture was filtered. The filter layer was dissolved in boiling toluene (benzene), was filtered when hot, was cooled and was filtered again. Recrystallisation from ethanol gave a product with m.p. 120.degree.-121.degree. C. Yield 24-27%. As a by-product o-nitrobenzoic acid was formed.
Example 2
Preparation of 4,4'-dinitrobibenzyl from p-nitro-toluene
The preparation was analogous to the previous example. Yield 91-99%. M.p. 179.degree.-181.degree. C.
Example 3
Preparation of 4,4'-dichloro-2,2'-dinitrotoluene from
2-nitro-4-chloro-toluene
The preparation was analogous to example 1. The product was precipitated from toluene with petroleum ether. Yield 23%. The IR-spectrum of the product was in accordance with the data of the literature.
The following table gives a summary of the performed experiments according to the method described above. The reaction time was 12 hours in all experiments and the ratio nitrotoluene/metal catalyst was 6.10.sup.3.
TABLE 1 ______________________________________
Yield
Nitrotoluene
Catalyst % Product
______________________________________
o-Nitrotoluene
VO(AcAc).sub.2
REFERENCES:
patent: 2596108 (1952-05-01), Treves
patent: 2965681 (1960-12-01), Stansbury, Jr. et al.
patent: 3006972 (1961-10-01), Fields et al.
patent: 3716590 (1973-02-01), Caraclacu et al.
patent: 3895055 (1975-01-01), Itatani et al.
patent: 3950434 (1976-04-01), Kominami et al.
Journal of the American Chemical Society, vol. 70, No. 2, Mar. 1948 (Caston), G. R. Treves, "Investigation of the Oxidative Condensation of 2-Methoxy-4-nitrotoulene, the Use of Oxidative Catalysts", pp. 875-876.
Chemical Dynamics Development AB
Terapane John F.
Wolffe Susan
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