Process for preparing 3-isochromanone

Details Process for preparing 3-isochromanone Process for preparing 3-isochromanone

1999-12-08

2001-02-06

Aulakh, Charanjit S. (Department: 1612)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C570S101000

Reexamination Certificate

active

06184392

ABSTRACT:

This invention relates to a chemical process and more particularly to a process for preparing 3-isochromanone which is useful in the manufacture of certain agricultural products.
3-Isochromanone is a well known compound and a number of methods for its preparation are described in the chemical literature. In particular, a process is described in WO97/00850 which comprises reacting an o-xylene-&agr;,&agr;′-dihalide derivative with carbon monoxide and water in an organic solvent in the presence of a catalyst and a hydrogen halide capturing agent followed by treatment with an acid. It has now been found that the final acid treatment can be obviated by careful control of the pH during reaction, thereby providing a simpler process.
Thus, according to the present invention, there is provided a process for the preparation of 3-isochromanone which comprises reacting an o-xylene-&agr;,&agr;′-dihalide with carbon monoxide and water in the presence of a catalyst, characterised in that the pH of the reaction is maintained between 7 and 11.
The o-xylene-&agr;,&agr;′-dihalide starting material has the general formula:
where X is a halogen atom such as chlorine, bromine or iodine, especially chlorine or bromine. o-Xylene-&agr;,&agr;′-dichloride is a particularly convenient starting material.
The pH of the reaction is maintained by having present at the beginning a sufficient amount of a suitable base, or by the controlled addition during the reaction of a suitable base at a suitable rate, or by buffering. Alternatively, it may be maintained by a combination of these methods. Suitable bases include inorganic bases such as alkali metal or alkaline earth metal carbonates, bicarbonates or hydroxides, for example, sodium or magnesium carbonate, potassium or sodium bicarbonate or calcium or magnesium hydroxide, or organic bases such as carboxylate salts, for example acetate salts. Quantities and rates of addition of the base should be sufficient to maintain the pH in the range of 7 to 11, suitably 7 to 10, for example, 8 to 10.
Conveniently the process is carried out in an organic solvent which is inert to the reactants. Any suitable organic solvent may be used, either water soluble or water immiscible. Examples are saturated or aromatic hydrocarbons or halogenated derivatives thereof, such as chlorinated or fluorinated derivatives, for example methylene chloride, toluene or chloro- or fluorobenzene, polar aprotic solvents such as N,N-dimethylformamide, ethers such as cyclic ethers, for example tetrahydrofuran, aliphatic ethers, for example dialkyl ethers, aromatic ethers, for example phenyl alkyl ethers and polyethers such as polyethylene glycols and variants thereof, for example, end-capped polyether glycols, alcohols such as t-butanol, nitrites, amines, ketones and esters. The choice of solvent may be influenced by the use to which the 3-isochromanone will be put. Of particular interest are C
1-6
and especially C
1-4
dialkyl ethers like methyl t-butyl ether and methyl t-amyl ether. It is envisaged, however, that the reaction may be carried out in water with no solvent present. One example of this is to carry out the process at a temperature above the melting point of the o-xylene-&agr;,&agr;′-dihalide, which, in the case of o-xylene-&agr;,&agr;′-dichloride is about 55° C. As 3-isochromanone melts at 82 to 84° C., a reaction temperature below this may be of advantage in allowing 3-isochromanone to crystallise out and allowing isolation of 3-isochromanone by filtration or extraction in a suitable solvent.
The total water requirement may be introduced at the start of reaction, added continuously or stepwise during reaction or formed in situ.
The carbon monoxide will normally be added by feeding a continuous supply of the gas into the reaction mixture either at atmospheric pressure or at pressures up to 100 atmospheres, for example at from 1 to 5 atmospheres. The pressure chosen will depend on the equipment in which the reaction is carried out and the required reaction rates and yield.
Any suitable carbonylation catalyst may be used in the process of the invention, particularly Group VIII (first, second and third triads) metal catalysts, for example palladium, cobalt or iron catalysts. Especially suitable are palladium catalysts, for example palladium (0) and palladium (II) catalysts, which may be water-soluble or water-insoluble, supported on a carrier, such as carbon, silica, calcium carbonate, a clay such as Montmorillonite, a polymer or other inert solid, or unsupported. Supported catalysts have the advantage of facilitating catalyst recovery and recycling. Ligands such as triphenylphosphine may be used in conjunction with certain palladium catalysts or it may be beneficial to pre-reduce the catalyst with hydrogen, or another suitable reducing agent.
Suitable water-soluble palladium catalysts in the form of phoshine complexes are described, for example, by J. Kiji et al in
Chem. Lett.,
957-960 (1988). Suitable water-insoluble palladium catalysts include bis(triphenylphosphine)palladium dichloride and tetrakis(triphenylphosphine)palladium (0) which are described by L. Cassar et al in
J. Organometallic Chem.,
121 (1976), C55-56, in DE-A-2526046 and by X. Huang et al in
Chem.
&
Ind., Sep.
3, 1990, 548. Palladium (II) catalysed carbonylation reactions are also discussed by V. Grushin et al in
Organometallics,
12 (5), 1890-1901 (1993). The use of a supported carbonylation catalyst in the form of palladium-black is described by T. Ito et al in
Bull. Chem. Soc. Japan,
48 (7), 2091-2094 (1975). The use of soluble triphenylphosphine ligands to activate palladium catalysts is described by D. Bergbreiter et al in
J. Mol. Catalysis,
74 (1992), 409-419. Other suitable catalysts and ligands, including water soluble ones, are described in WO 97/00850. The ligands may be used in amounts up to 20 mole equivalents of palladium, and suitably in the range of from 0.5 to 5.0 mole equivalents of palladium. The amount of palladium catalyst used may be in the range of 0.000001 to 0.5 mole equivalents of the o-xylene-&agr;,&agr;′-dihalide.
When the process is carried out in a two-phase system, for example when a water-immiscible solvent is used, it may be advantageous to include a phase transfer catalyst. By the term “phase transfer catalyst” is meant a substance which, being at least partly present in or wetted by a first (usually organic) phase, promotes reaction between a reactant in the first phase and a reactant which it transfers to the first phase from a second (usually aqueous but sometimes solid) phase. After reaction, the phase transfer catalyst is released for transferring further reactant. Phase transfer catalysts are reviewed by E. V. Dehmlow in
Angewante Chemie
(International Edition), 13 (3), 170 (1974). Other reviews are by Jozef Dockx in
Synthesis
(1973), 441-456 and by C. M. Starks in JACS., (93) 1, Jan. 13, 1971, 195-199.
Suitably the phase transfer catalyst is a quaternary ammonium or phosphonium salt preferably containing bulky organic groups, usually alkyl or aralkyl groups, to make it soluble in the organic phase. It is preferred that the phase catalyst is a tetraalkyl or aralkyl (eg benzyl) trialkyl ammonium or phosphonium salt in which the total number of carbon atoms attached to each nitrogen or phosphorus atom is greater than 10. There is little advantage in the number being above 70. It is especially preferred that the number should be in the range of from 16 to 40.
Examples of quaternary ammonium salts are: cetyltrimethylammonium bromide, dicetyldimethylammonium chloride, octyltributylammonium bromide, trioctylmethylammonium chloride (available as Aliquat™ 336), benzyldimethyllaurylammonium chloride, benzyltriethylammonium chloride, dilauryldimethylammonium chloride, tetrabutylammonium bromide and dieicosyldimethylammonium chloride. Examples of quaternary phosphonium salts are cetyltripropylphosphonium bromide and triphenylethylphosphonium bromide. Other phase transfer catalysts which may be suitable include crown ethers and pol

Affiliated with

Also associated with

Rating

Process for preparing 3-isochromanone does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for preparing 3-isochromanone, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing 3-isochromanone will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2581450