Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
This invention relates to an improved process for the prepar-
ation of benzoyl halides and meta-halosulfonylbenzoyl halides and,
more particularly, to such process involving the reaction of benzo-
trihalide with sulfuric acid.
~ Benzoyl halides and chlorosulfonylbenzoyl halides are well
i known in the chemical industry and have been employed in as inter-
mediates 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 areemployed 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; pharma-
ceuticals; 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. Patent 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. Patent 3,290,370, to Weil and Lisanke, disclose the prep-
aration of m-chlorosulfonylbenzoyl chloride by reaction of benzotri-
chloride 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
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disposal thereof. In addition, to obtain high yields of the desired
m-chlorosulfonylbenzoyl chloride, substantial excess of the chloro-
sulfonic acid is employed, presenting additional problems of separa-
tion, and disposal or recycling thereof.
U.S. Patent 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 halobenzoylsulfonyl
halides, it will be appreciated that still further improvements in
efficient utilization of reactants is desirable as well as improve-
ments 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 prepar-
. 20 ation 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 a
sulfuric acid sulfonating agent with a benzotrihalide compound of the
formula: CX3
.' I
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
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least one Y substituent at a meta position is hydrogen. In the above
formula, the preferred alkyl groups represented by Y are those of one
to six carbon atoms and the preferred haloalkyl groups are chloro-
alkyl 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 sub-
stituents, such as nitro- or tri-halomethyl, are present on the ring.
The process is carried out by addition of the benzotrihalide to
a sulfuric acid medium. As the sulfuric acid medium, there may be
employed sulfuric acid per se or a mixture of sulfuric acid and sulfur
trioxide, commonly referred to as oleum. The co-products prepared in
this manner are benzoyl halides and meta-halosulfon~ylbenzoyl halides
characterized, respectively by the formulas:
O O
C - X C - X
Y5 ~1 and Y~
~ S02X
wherein Y is as defined herein above.
DESCRIPTION OF PREFERRED EMBODIMENTS
The preferred benzotrihalide startiny materials are benzotri-
chloride compounds characterized by the formula:
CIC13
Y2
wherein Y is chlorine or hydrogen, especially benzotrichloride and
o-chloro-, m-chloro-, and p-chlorobenzotrichloride. These compounds
are reacted with sulfuric acid or olewn, in accordance with the process
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of this invention, to prepare correspondingly substituted benzoyl
chlorides and m-chlorosulfonylbenzoyl chlorides. Thus, when benzo-
trichloride 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-chlorobenzotri-
chloride 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-
chlorobenzoyl chloride and 5-chloro-3-chlorosulfonylbenzoyl chloride.
The use of sulfuric acid or oleum 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 pre-
dictably varied, depending on the composition of the sulfuric acid
reactant.
When sulfuric acid per se is employed, it has been Found that,
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
w;ll be produced. Thus, by controlling the strength of the sulfuric
acid reactant, the proportion of co-products may be varied accord-
ingly.
When benzotrihalide is sulfonated in accordance with this inven-
tion, the use of sulfuric acid of lower strength, such as about 50 to
about 75% will result in increased proportion of benzoyl halide pro-
duced whereas the use of sulfuric acid of higher strength, such as75 to about 100% sulfuric acid, will result in an increase in the pro-
portion of halosulfonylbenzoyl halide produced. In a preferred
embodiment of the invention, where it is desired to maximize the pro-
duction of halosulfonylbenzoyl halide ard especially the meta-isolrer
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thereof, it is preferred to employ a sulfuric acid composition of
at least about 90 to about 100 percent sulfuric acid.
01eum, a mixture containing sulfur trioxide and anhydrous sul-
furic acid, is available in various compositions, depending on the
sulfuric acid, is available in various compositions, depending on
the sulfur trioxide content, and may be employed as a sulfonating
agent in accordance with this invention, in concentrations as high
as 75% or higher. The co~non commercially available olewn compo-
sitions are those containing about 20, 40, 50 and 65 percent sulfur
trioxide. The physical properties, such as specific gravity and
melting point of oleum compositions vary according to the percent
sulfur trioxide present. For example, 20 percent oleum has a melting
point of about -10 Celsius and 65 percent oleum has a melting point
of about 0 Celsius while an intermediate composition of ~5 percent
oleum melts at about 35 Celsius. The most preferred oleum compo-
sitions for use as the sulFuric acid sulfonating agents in the process
of this invention are those having about 18 to about 70 percent sulfur
trioxide, and most preferably oleum compositions having a melting
point below ambient temperature.
It has been found that when benzotrihalide is sulfonated in
accordance with this invention, the use of oleum o-F lower strength,
such as about 18 to about 25 percent sulfur trioxide will result in
increased proportion oF benzoyl halide produced whereas the use of
oleum of higher strength, such as 65~ sulfur trioxide, will result in
an increase in the proportion of halosulfonylbenzoyl halide produced.
The advantage of such controllable 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 thereof7 it is preferred to
employ an oleum composition of about 55 to about 70 percent sulfur
trioxide.
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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 or lower to as
high as 200 Celsius or higher. Temperatures as low as the freezing
point of the reaction medium, may be employed, for example, as low as
the -10 Celsius (the approximate freezing point of 20% oleum). How-
ever, such lower temperatures provide no advantage and thus are not
preferred. Similarly, higher temperatures, such as about about 200
Celsius are not preferred since it has been found that an increase in
undesirable residues may result. When the sulfonating agent is oleum,
the most preferred temperature at which the present process is carried
out is from about 10 Celsius degrees of the temperature at which sul-
fur trioxide distills out of the reaction mixtllre up to the refluxing
temperature. The temperature at which sulfur trioxide will distill
out of the reaction mixture will increase as the percentage of sulfur
trioxide in the oleum decreases. Thus, the preferred starting tem-
perature will vary depending on strength of the oleum composition
employed. Furthermore, as the sulfonation reaction progresses and
sulfur trioxide is consumed it is preferred to increase the tempera-
ture of the reaction mixture accordingly. In an alternative embodi-
ment, the content of sulfur trioxide may be maintained at a desired
level by continuous or periodic addition of sulfur trioxide to the
oleum reaction mixtures as the reaction progresses.
In a preferred mode, using 65 percent oleum as the sulFonating
agent, and adding benzotrichloride thereto, the sulfonating agent is
initially maintained at below about 60 and preferably at about 20
to about 50 Celsius. As additional benzotrichloride reactant is
added and the reaction progresses, depleting the amount of sulfur
trioxide present, the temperature is gradually increased, either con-
tinuously, or in stages, to a preferred maximum temperature in thelater stayes of reaction, as the sulfonating agent is consumed to
about 140 to about 170 Celsius. It has been found that the reaction
initially proceeds exothermically as the sulfur trioxide content of
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the oleum decreases. Thereafter, HCl is evolved, the reaction becomes
endothermic and heat input to the reaction mixture may be increased
accordingly.
When a lower strength oleum, such as 20 percent oleum is em-
ployed, higher starting temperatures, such as about 80 to 110Celsius are preferred, with an increase to about 140 to about 170
Celsius in the later stages of reaction, as the sulfonating agent is
consumed.
When sulfuric acid per se is employed as the sulfonating agent,
the preferred temperature at which the process is carried out is
about 50 to about 200 Celsius, and most preferably about 80~ to
about 180 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 benzotri-
halide to the sulfonating agent and proceeding in this manner as the
sulfonating agent is consumed. The gradual addition of the benzotri-
halide may be continuous or intermittant. Utilizing this order of
addition, it has been found that undesirable sicle reactions may be
substnatially avoided. In addition, the reaction may be cont;nued
in this manner until substantially all of the sulfonating agent and
any water formed is consumed. In practice, an excess of benzotri-
halide may be added, thus allowing substantially complete utilization
of the sulfonating agent.
The following specific examples are provided to further illus-
trate 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
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not to be construed as a limitation on the invention. In the ex-
amples, unless otherwise indicated, all parts and percentages are
by weight and all temperatures are in degrees Celsius.
EXAMPLE I
A reaction vessel, equipped with a reflux condenser, ther-
mometer, external temperature control means, and stirring means, was
charged with 46.9 parts of 20% oleum and heated to about 100~ C. A
total of 195.48 parts of benzotrichloride was added slowly over a
period of 3.2 hours. During that time the reaction temperature rose
initially to about 115 C. Then, with additional external heat the
temperature was gradually raised to about 1~0 C. and maintained
- thereat for an additional 2.5 hours following the addition of the
benzotrichloride. Simple distillation of the reaction product
yielded 84.2 parts of a first fraction containing about 70% benzoyl
chloride and about 30% unreacted BTC, and a second fraction consis-
ting of 92.6 parts of m-chlorosulfonylbenzoyl chloride. Analysis
I of the m-chlorosulfonylbenzoyl chloride product indicated approxi-
mately 95.8% meta-isomer; 0.1% ortho-isomer; and 4.0% para-isomer.
EXAMPLE II
A reaction vessel was charged with 256.7 parts of 65% oleum
and heated to about ~6 C. A total of 684.2 parts of benzotri-
chloride was added slowly to the oleum over a period of 1.5 hours.
During the first 30-40% of the addition of the benzotrichloride, the
temperature was allowed to rise (with external cooling) to about 100
C. Thereafter the temperature was increased gradually, with external
heating, to a maximum of about 150 C. during the final stages of
benzotrichloride addition and maintained thereat for an additional
2 hours. Separation and analysis of the reaction product yielded
108.9 parts of benzoyl chloride and 577.5 parts m-chlorosulfonyl-
benzoyl chloride containing 96.1% meta-isomer; 0.1% ortho-isomer;
and 3.8% para-isomer.
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EXAMPLE III
A reaction vessel, equipped with a reflux condenser, ther~
mometer, external temperature control means, and stirring means,
was charged with 51.6 parts of 95-98% H2S04 and heated to about
150 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 C. Following the addition
of benzotrichloride the temperature was maintained at about 150 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 fraction
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 examples, substituted benzotrihalides are reacted with
sulfuric acid or oleum to yield substituted benzoyl chlorides and
substituted m-halosulfonylbenzoyl halides.
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