Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1997-06-24
1998-09-22
Reamer, James H.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568327, C07C 4561
Patent
active
058115854
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present process provides an improved method for making 5-chloro-2,3-dihydro-1H-inden-1-one. Said inden-1-one is useful as an intermediate for making arthropodicidal oxadiazines such as methyl disclosed in WO 92/11249.
A process for preparing 5-chloro-2,3-dihydro-1H-inden-1-one is disclosed in Olivier, M.; Marechal, E. Bulletin de la Societe Chimique de France (1973), 11, 3096-3099 where 3-chloro-1-(4-chlorophenyl)-1-propanone (alternately referred to as 3,4'-dichloropropiophenone) is treated with a mixture of aluminum chloride and sodium chloride at 180.degree. C. Although the process disclosed in this reference begins with the same precursor as is used in the present process, the large amounts of aluminum chloride and sodium chloride required are difficult to handle, especially on a commercial scale at the required elevated temperature. In addition, any unused aluminum chloride and sodium chloride reactants and any by-products of the desired reaction represent a substantial disposal problem.
SUMMARY OF THE INVENTION
The present invention relates to an improved process for making 5-chloro-2,3-dihydro-1H-inden-1-one comprising adding a solution of 3-chloro-1-(4-chlorophenyl)-1-propanone in an inert solvent to sulfuric acid at 90.degree.-150.degree. C. in a way that minimizes byproduct reactions and product decomposition and maximizes yield and product purity.
In another embodiment, the present invention relates to an improved process for making 5-chloro-2,3-dihydro-1H-inden-1-one comprising contacting 3-chloro-1-(4-chlorophenyl)-1-propanone, optionally in the presence of an inert solvent, with a solid acid catalyst at 200.degree.-425.degree. C. in a continuous flow reactor. The process of the present invention is depicted by the following equation. ##STR1##
DETAILED DESCRIPTION OF THE INVENTION
In the present process, 3-chloro-1-(4-chlorophenyl)-1-propanone (hereafter, reactant) is contacted with sulfuric acid at a temperature of between about 90.degree.-150.degree. C. or with a solid acid catalyst at 200.degree.-425.degree. C. It is believed that under these conditions the reactant will rapidly eliminate HCl to form an intermediate, probably 1-(4-chlorophenyl)-2-propen-1-one. It is further believed that this intermediate then has the potential to react along at least two competing pathways: one path involves intramolecular cyclization to form the desired 5-chloro-2,3-dihydro-1H-1-one (hereafter, product), a second path involves intermolecular reaction between molecules of intermediate to form undesired oligomeric byproducts. Oligomeric byproducts are believed to represent the primary yield loss. Under the conditions defined above, the rate of dehydrochlorination of the reactant is believed to be fast relative to the rate at which the intermediate reacts to form product or byproduct.
In the embodiment of the present invention in which sulfuric acid is used, it has been found that product yield was increased by limiting the rate of addition of reactant to the reaction mixture and by diluting the reactant in inert solvent. It is believed that decreasing the rate of addition of the reactant to the reaction mixture and providing the reactant to the reaction mixture in dilute solution lowers the concentration of the intermediate in the reaction mixture. The rate of intramolecular cyclization of intermediate (to desired product) should be unaffected by concentration of the intermediate, whereas the rate of intermolecular reaction of the intermediate (to undesired oligomeric byproduct) should decrease with decreasing concentration of the intermediate.
In the embodiment of the present invention in which sulfuric acid is used, the rate of addition of reactant to the reaction mixture is in the range of about 0.05-1.0 moles of 3-chloro-1-(4-chlorophenyl)-1-propanone per liter of sulfuric acid (based on concentrated sulfuric acid, 95% by weight assay) per hour. At faster addition rates product yield becomes unacceptably low as formation of oligomeric byproduct becomes greater. At
REFERENCES:
patent: 2815382 (1957-12-01), Carpenter et al.
patent: 3509215 (1970-04-01), Wood et al.
patent: 4568782 (1986-02-01), Pagnotte et al.
Olivier et al, Bull de la Chim de France, vol. 11, pp. 3096-3099, 1973.
Marechal et al, Bull de la Chim de France, vol. 6 pp. 1981-1989, 1969.
Corbin David Richard
Dumas Donald Joseph
Sengupta Sourav Kumar
E. I. Du Pont de Nemours and Company
Reamer James H.
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