Process for the preparation of benzoyl halide and halosulfonylbenzoyl halide

A process for the preparation of benzoyl halide and meta-halosulfonyl benzoyl halide comprises adding to sulfuric acid and reacting therewith a benzotrihalide compound characterized by the formula: ##STR1## wherein X is bromine or chlorine and Y is individually selected from the group consisting of fluorine, chlorine, bromine, iodine, alkyl, preferably of one to six carbon atoms, halosubstituted alkyl, preferably trichloromethyl or tribromomethyl, aryl, preferably phenyl, and hydrogen, with the proviso that at least one Y substituent at a meta position is hydrogen.

BACKGROUND OF THE INVENTION 
This invention relates to an improved process for the preparation of 
benzoyl halides and meta-halosulfonylbenzoyl halides and, more 
particularly, to such process involving the reaction of benzotrihalide 
with sulfuric acid. 
Benzoyl halides and chlorosulfonylbenzoyl halides are well known in the 
chemical industry and have been employed in as intermediates for a variety 
of known and useful end products. Benzoyl halides, are highly reactive 
acid halides, useful in a variety of reactions to introduce the benzoyl 
group into organic compounds, especially through Friedel-Crafts reactions. 
Benzoyl halides are employed in the preparation of perfumes, 
pharmaceuticals, dyes, resins and pesticides. Similarly, 
halosulfonylbenzoyl halides are known to be useful for a variety of 
purposes and have been employed, for example, as polymerization catalysts 
and as intermediates in the preparation of pharmaceuticals and azo dyes. 
In addition, meta-halosulfonylbenzoyl halides, may be desulfonylated in a 
known manner to prepare m-halobenzoyl halides, which, in turn, are useful 
for various purposes in the chemical industry, including, for example, as 
chemical intermediates for the preparation of dyes; pharmaceuticals; 
agricultural chemicals; as well as various other organic chemical end 
products. 
Various methods for the preparation of benzoyl halides or 
meta-sulfonylbenzoyl halides are known in the art. It is known, for 
example, from U.S. Pat. No. 3,691,217, that benzoyl chlorides and 
benzaldehydes may be produced by reacting benzo polychloromethanes, such 
as benzotrichloride, with an organic carboxylic acid in the presence of a 
tin chloride catalyst. 
U.S. Pat. No. 3,290,370, to Weil and Lisanke, disclose the preparation of 
m-chlorosulfonylbenzoyl chloride by reaction of benzotrichloride with 
chlorosulfonic acid. The stoichiometry of the reaction is such that, even 
under ideal conditions, for each mole of desired product, two moles of 
mineral acid are produced, with the need for disposal thereof. In 
addition, to obtain high yields of the desired m-chlorosulfonylbenzoyl 
chloride, substantial excess of the chlorosulfonic acid is employed, 
presenting additional problems of separation, and disposal or recycling 
thereof. 
U.S. Pat. No. 3,322,822 to Gelfand, discloses the preparation of 
m-chlorosulfonylbenzoyl chloride by reaction of benzotrichloride and 
sulfur trioxide. With the use of substantial excess of sulfur trioxide 
reactant, yields of m-chlorosulfonylbenzoyl chloride as high as 65% are 
shown to be obtainable. 
Although the prior art provides a variety of processes for the preparation 
of either benzoyl halides or halosulfonylbenzoyl halides, it will be 
appreciated that still further improvements in efficient utilization of 
reactants is desirable as well as improvements in the yield of the 
meta-isomer of halosulfonylbenzoyl halide obtainable. 
Accordingly, it is an object of this invention to provide an improved 
process for the preparation of halosulfonylbenzoyl halides wherein the 
meta-isomer thereof may be selectively produced in high yields. It is a 
further object to provide a process for the preparation of co-products, 
benzoyl halides and halosulfonylbenzoyl halides wherein the proportional 
yield of each may be controllably varied. 
SUMMARY OF THE INVENTION 
This invention provides a process for the co-production of benzoyl halides 
and m-halosulfonylbenzoyl halides by reaction of sulfuric acid with a 
benzotrihalide compound of the formula: 
##STR2## 
wherein X is bromine or chlorine and Y is individually selected from the 
group consisting of hydrogen, fluorine, chlorine, bromine, iodine, alkyl, 
halosubstituted alkyl, and aryl, with the proviso that at least one Y 
substituent at a meta position is hydrogen. In the above formula, the 
preferred alkyl group represented by Y are those of one to six carbon 
atoms and the preferred haloalkyl groups are chloroalkyl and bromoalkyl of 
one to six carbon atoms, and most preferably trichloromethyl or 
tribromomethyl. The preferred aryl substituents are phenyl or substituted 
phenyl wherein electron-withdrawing substituents, such as nitro- or 
tri-halomethyl, are present on the ring. 
The process is carried out by addition of the benzotrihalide to sulfuric 
acid. The co-products prepared in this manner are benzoyl halides and 
meta-halosulfonylbenzoyl halides characterized, respectively by the 
formulas: 
##STR3## 
wherein Y is as defined herein above. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
The preferred benzotrihalide starting materials are benzotrichloride 
compounds characterized by the formula: 
##STR4## 
wherein Y is chlorine or hydrogen; especially benzotrichloride and 
o-chloro,-m-chloro-, and p-chlorobenzotrichloride. These compounds are 
reacted with sulfuric acid, in accordance with the process of this 
invention, to prepare correspondingly substituted benzoyl chlorides and 
m-chlorosulfonylbenzoyl chlorides. Thus, when benzotrichloride is employed 
as the starting material, the co-products obtained by the process of this 
invention will be benzoyl chloride and m-chlorosulfonylbenzoyl chloride. 
Utilizing p-chlorobenzotrichloride as the starting material results in the 
co-production of p-chloro-benzoyl chloride and 
4-chloro-3-chlorosulfonylbenzoyl chloride. Starting with 
m-chlorobenzotrichloride yields, as co-products, m-chloro-benzoyl chloride 
and 5-chloro-3-chlorosulfonylbenzoyl chloride. 
The use of sulfuric acid as a sulfonating agent in the process of this 
invention provides specific advantages in terms of the high yield of 
meta-isomer obtained in the halosulfonylbenzoyl halide product and, in 
addition, provides an advantageous degree of control over the proportional 
yield of the co-products obtained. It has been found that the proportional 
yield of co-products may be predictably varied, depending on the 
composition of the sulfuric acid reactant. In general, the higher the 
strength of the sulfuric acid employed (and thus the lower the amount of 
water present), the higher the proportion of m-halosulfonylbenzoyl halide 
that will be produced. Conversely, the greater the amount of water present 
(i.e. the weaker the sulfuric acid), the higher the proportion of benzoyl 
halide that will be produced. Thus, by controlling the strength of the 
sulfuric acid reactant, the proportion of co-products may be varied 
accordingly. 
It has been found that when benzotrihalide is sulfonated in accordance with 
this invention, the use of sulfuric acid of lower strength, such as about 
50 to about 75% will result in increased proportion of benzoyl halide 
produced whereas the use of sulfuric acid of higher strength, such as 75 
to about 100% sulfuric acid, will result in an increase in the proportion 
of halosulfonylbenzoyl halide produced. The advantage of such conrollable 
variation of co-products resides in the ease with which the process may be 
varied to increase or decrease the proportional yield of either 
co-product, depending on market needs, economic factors or other 
considerations prevailing at any given time. In a preferred embodiment of 
the invention, where it is desired to maximize the production of 
halosulfonylbenzoyl halide and especially the meta-isomer thereof, it is 
preferred to employ a sulfuric acid composition of about 90 to about 100 
percent sulfuric acid. 
The temperature at which the process of this invention may be carried out, 
under atmospheric conditions, may vary considerably, for example from 
temperatures as low as about 20.degree. or lower to as high as 200.degree. 
Celsius or higher. Temperatures as low as the freezing point of the 
sulfuric acid reactant may be employed, however, such lower temperatures 
provide no advantage and thus are not preferred. Similarly, higher 
temperatures, such as above about 200.degree. Celsius are not preferred 
since an increase in undesirable residues may result. 
The preferred temperature at which the present process is carried out is 
from about 50.degree. to about 200.degree. Celsius, and most preferably 
about 80.degree. to about 180.degree. Celsius. 
The temperature considerations suggested are premised on the basis of a 
reaction at about atmospheric pressure. Sub-atmospheric pressures may be 
employed but are not preferred. Super-atmospheric pressures may be 
employed with appropriate changes in preferred temperatures in accordance 
with the vapor pressure changes resulting from such pressure increase. 
It has been found particularly advantageous to carry out the process of 
this invention by the gradual addition of the benzotrihalide to the 
sulfuric acid sulfonating agent and proceeding in this manner as the 
sulfonating agent is consumed. The gradual addition of the benzotrihalide 
may be continuous or intermittant. Utilizing this order of addition, it 
has been found that undesirable side reactions may be substantially 
avoided. In addition, the reaction may be continued in this manner until 
substantially all of the sulfonating agent and water present is consumed. 
In practice, an excess of benzotrihalide may be added. thus allowing 
substantially complete utilization of the sulfonating agent. 
The following specific examples are provided to further illustrate this 
invention and the manner in which it may be carried out. It will be 
understood, however, that the specific details given in the examples have 
been chosen for purpose of illustration and are not to be construed as a 
limitation on the invention. In the examples, unless otherwise indicated, 
all parts and percentages are by weight and all temperatures are in 
degrees Celsius.

EXAMPLE 1 
A reaction vessel, equipped with a reflux condenser, thermometer, external 
temperature control means, and stirring means, was charged with 51.6 parts 
of 95-98% H.sub.2 SO.sub.4 and heated to about 150.degree. C. A total of 
223.5 parts of benzotrichloride was added slowly over a period of 3.7 
hours, during which time the reaction temperature was maintained at about 
150.degree. C. Following the addition of benzotrichloride the temperature 
was maintained at about 150.degree. C., with stirring for an additional 
hour. The reaction mixture was then distilled at reduced pressure to yield 
91.3 parts of a first fraction containing about 90% benzoyl chloride and a 
second fracation of 106.3 parts of m-chlorosulfonylbenzoyl chloride. 
Analysis of the m-chlorosulfonylbenzoyl chloride produce indicated 
approximately 95.2% meta-isomer; 0.06 ortho-isomer; and 4.8% para-isomer. 
In a similar manner, following the general procedure of the foregoing 
example, substituted benzotrihalides are reacted with sulfuric acid to 
yield substituted benzoyl chlorides and substituted m-halosulfonylbenzoyl 
halides.