The Manufacture or Production of Benzamide Orthosulphonic Acid, and of Saccharin and other Derivatives thereof.
Year: 1895

page_text: Date of Application, 23rd Feb., 1895
Complete Specification Left, 23rd Nov., 1895-Accepted, 28th Dec., 1895
PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE FARBENFABRIKEN, vormals FRIEDRICH
BAYER & Co., of Elberfeld, Germany,]
The Manufacture or Production of Benzamide Orthosulphonic Acid,
and of Saccharin and other Derivatives thereof.
I HENRY EDWARD NEWTON of The Office for Patents, 6 Bream's Buildings,
Chancery Lane in the County of London, Patent Agent, do hereby declare the
nature of this invention to be as follows:-
The present invention relates to the manufacture or production of benzamide
orthosulphonic acid, and of saccharin and other derivatives thereof.
Sulphonic acids of benzamide or benzamide sulphonic acids, have not yet been
produced. It is known that Engelhardt has described (see Jahresberichte der
Chemie, of the year 1858, page 278) a product which is formed by sulphonating
cyano-benzene, but the compound thus formed is not ascertained to be a sulphonic
derivative of benzamide.
According to the researches of my foreign correspondents, the usual method of
preparing amides of aromatic acids, which consists in treating the acids with
phosphor haloids, and in subsequently allowing ammonia, or the like, to act on the
first formed acid chlorides, cannot be used for producing a sulphonic derivative of
benzamide from benzene sulpho carboxylic acid, as the action of phosphor haloids on
benzene sulpho carboxylic acid proceeds in such a manner that the sulphonic group is
changed at once. Owing to this fact, the production of benzoylchloride sulphonic
acid (sulphonic derivative of benzoylchloride) cannot be effected in the last-named
way.
My foreign correspondents have now found a new and simple method of pro-
ducing the orthosulphonic derivative of benzamide, or benzamide orthosulphonic
acid, which product possesses technical value according to the researches of my
foreign correspondents.
This process, in general, consists in heating benzene ortho sulpho carboxylic acid,
or salts thereof, with ammonium sulphocyanate, which, as is known, melts with
readiness. It is to be noted that this method of producing amides of aromatic
carboxylic acids has not been hitherto applied to sulphonic derivatives of aromatic
carboxylic acids, and it could not be foreseen whether the sulphonic group would
or would not prevent the formation of the amides.
One of the methods which can be used for producing the orthosulphonic deriva-
tive of benzamide is illustrated by the following example, which is merely typical.
The parts are by weight.

page_text: product thus obtained is sufficiently pure for practical use.
It is obtained in pure
state by recrystallization from water or dilute alcohol, and forms then large glass-
like crystals. It possesses the following formula:-
The potassium salt of benzamide ortho-sulphonic acid dissolves very readily in
water, and differs by this property from the potassium salt of benzene ortho sulpho
carboxylic acid. When boiled for a longer period with dilute soda lye, the amide
is saponified, ammonia being disengaged.
In producing the aforesaid benzamide ortho sulphonic acid, my foreign corre-
spondents do not limit themselves to the directions given in the preceding first
example, as these can be varied. For instance the proportions of the ingredients
used, the temperature, and the duration of heating, can vary within certain limits,
without departing thereby from the nature of this part of the invention.
According to the researches of my foreign correspondents, the benzamide ortho-
sulphonic acid hereinbefore defined can profitably be used as initial material for
producing benzoic sulphimide or saccharin. This method differs from these
hitherto known, and in use, for preparing saccharin, that is to say, from those
methods which consist either in oxidising ortho-toluene sulphonic amide (see
Berichte der Deutschen Chemischen Gesellschaft, Volume 12, page 469, and the
German Patent No. 35211), or in "amidising" benzene ortho-sulpho-carboxylic
acid, for which purpose the benzene ortho sulpho carboxylic dichloride must be
used (see the Berichte der Deutschen Chemischen Gesellschaft, Volume 12,
page 473).
The process of converting benzamide orthosulphonic acid, or salts thereof, into
saccharin, in general, consists in treating the alkaline salts of the benzamide ortho-
sulphonic acid by means of phosphorus oxychloride (or agents acting in a similar
manner, such as phosphorus pentachloride or the like), converting the benzamide
ortho-sulphonic chloride thus produced into the corresponding sulphonic amide, viz.,
benzamide orthosulphonic amide, by a suitable treatment with ammonia or other
agents producing the same result; subsequently saponifying, for instance, by
boiling, with alkalies, the benzamide group contained in the aforementioned
benzamide ortho sulphonic amide; and finally in precipitating the saccharin by
acidulating with acids, or in any other suitable manner.
This new process compared with that process which here is to be taken into view,
and for which the benzene ortho sulphonic carboxylic acid is employed as initial
material, possesses the following advantages:-
1. The benzamide ortho sulphonic chloride is readily obtainable, even by means
of phosphorus oxychloride, whereas the conversion of benzene-ortho-sulphonic
carboxylic acid, into benzene ortho sulphonic carboxylic dichloride, necessitates
the use of phosphorus pentachloride, the employment of which, on a large scale is
attended with considerable difficulty.
2. The conversion of benzamide ortho sulphonic acid into benzamide ortho
sulphonic chloride, is effected by means of molecule of phosphorus oxychloride,
whilst 2 molecules of phosphorus pentachloride are necessary for converting the
benzene orthosulphonic carboxylic acid into the dichloride, as in this case the
hydroxy group of the carboxylic group must also be replaced by chlorine.
3. The benzamide ortho sulphonic chloride, owing to its greater stability, can be
transformed into the benzamide ortho sulphonic amide by means of watery ammonia
liquid, whilst the benzene ortho-sulphonic carboxylic dichloride is converted but

page_text: slightly into the sulphonic amide, and therefore ammonia gas, or ammonium
carbonate, is necessary for this conversion.
In view of these advantages, it is no matter if the uew process herein before
defined starts from the benzamide ortho sulphonic acid, particularly as but a slight
quantity of the cheap ammonium sulpho-cyanate is necessary for producing this
benzamide ortho sulphonic acid.
In order to illustrate the new process, the following example is given, which is
merely typical. The parts are by weight.
CONVERSION OF BENZAMIDE ORTHO SULPHONIC ACID INTO BENZOIC
SULPHIMIDE (SACCHARIN).
A nixture prepared from 500 parts of benzamide ortho sulphonate of potassium
and 500 parts of phosphorus oxychloride, is heated, during 2 hours, in a vessel
provided with a reflux condenser. The phosphorus oxychloride used in excess is
then distilled off. The resulting solid mass, after pulversing, is treated with cold
water, and the benzamide ortho sulphonic chloride which remains in the form of a
white crystalline powder, insoluble in water, is filtered off. It is gradually intro-
duced into 500 parts of ammonia liquor (containing 20 per cent. of pure ammonia),
while cooling by means of ice. The resulting liquid mixture is finally heated during
a short time on a water bath. The benzamide ortho sulphonic chloride is thus
entirely converted into the benzamide ortho sulphonic amide, which forms a heavy
white crystalline powder. In order to saponify the benzamide group, the benzamide
sulphonic amide is boiled, during about 4 hours, with about five times the quantity
of soda lye (containing 4 per cent. of sodium hydroxide). The saccharin is finally
precipitated by adding mineral acids to the resulting alkaline liquid, or in any other
suitable manner.
In order to convert benzamide ortho sulphonic acid, or its salts, into the herein-
before mentioned intermediate products, and finally into saccharin, my foreign
correspondents do not limit themselves to the particulars given in the foregoing
second example. The directions can be varied. For instance, the proportions of
the ingredients used can vary within certain limits; the phosphorus oxychloride
used can be replaced by other agents acting in the like or a similar manner (such
as phosphorus pentachloride or the like); stronger or weaker ammonia liquors may
be used in place of the ammonia liquor herein employed, and containing 20 per cent.
of pure ammonia; or the ammonia liquor may be replaced by other agents capable
of producing the same effect (such as ammonia gas, in which case closed vessels are
required to be used, or ammonium carbonate, or the like). Such or similar
modifications do not alter this part of the present invention.
Dated this 23rd day of Kebruary 1895
NEWTON & SON,
Agents for the Applicant.
The Manufacture or Production of Benzamide Orthosulphonic Acid,
and of Saccharin and other Derivatives thereof.
I HENRY EDWARD NEWTON of The Office for Patents, 6 Bream's Buildings,
Chancery Lane in the County of London, Patent Agent, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
The present invention relates to the manufacture or production of benzamide-
ortho-sulphonic acid, and of saccharin and other derivatives thereof.

page_text: It is well known that benzamide ortho sulphonic acid has been prepared by
C. Fahlberg and R. Barge (see Berichte der Deutschen Chemischen Gesellschaft,
Volume 22, page 759) by the action of ammonia or ortho-sulpho-benzoic-anhydride,
and later on, by Jesurun (sce Berichte der Deutschen Chemischen Gesellschaft,
Volume 26, page 2288), by heating ortho-cyano-benzene-sulphonic chloride with
water or alcohol.
These two methods, however, are of no practical value, as the materials required
can be obtained only with considerable difficulty.
My foreign correspondents have discovered a new and simple method of producing
the ortho-sulphonic derivative of benzamide, or benzamide-ortho-sulphonic acid,
the which product they find is of technical value..
This process,
in general terms, consists in heating benzene, ortho-sulpho carboxylic
acid, or salts thereof, with ammonium sulpho-cyanate.
One of the methods which can be used in practically producing the ortho
sulphonic derivative of benzamide, is illustrated by the following typical example.
The parts are by weight.
EXAMPLE A.
PRODUCTION OF BENZAMIDE-ORTHO-SULPHONIC ACID.
500 parts of the acid potassium salt of benzene-ortho-sulpho-carboxylic acid are
mixed with 300 parts of ammonium sulpho-cyanate, and the mixture is heated at
from 180 to 200 degrees Centigrade, during from 20 to 30. hours,, being stirred
meanwhile. The mass sets to a stiff cake, on cooling.. It is finely ground, and
digested with boiling alcohol, and the potassium. salti of the benzamide-ortho-
sulphonic acid which is left in the form of sandy crystals, is separated by filtration.
It is obtained in a
The product thus obtained is sufficiently pure for practical use.
purer state by re-crystallization from water or dilute alcohol, and then forms large
glass-like crystals. It is represented by the following formula:-
The potassium salt of benzamide ortho-sulphonic acid dissolves very readily in
water, differing in this respect from the potassium salt of benzene ortho-sulpho-
carboxylic acid. When boiled for a longer period with diluted soda-lye, the amide
is hydrolysed, ammonia being disengaged.
In producing the aforesaid benzamide-ortho-sulphonic acid, my foreign corre-
spondents do not limit themselves to the directions given in the preceding
Example A, as these can be varied. For instance, the proportions of the
ingredients used, the temperature, and the duration of heating, can vary within
certain limits, without departing thereby from the nature of this part of the
invention.
According to the researches of my foreign correspondents, the benzamide-ortho-
sulphonic acid herein before defined can be profitably used initially as material in
producing benzoic sulphimide or saccharin. This method differs from those
hitherto known and used in preparing saccharin, that is to say, from those methods,
which consist either in oxidising ortho toluene-sulphonic amide (see Berichte der
Deutschen Chemischen Gesellschaft, Volume 12, page 469, and the German Patent
No. 35211), or in "amidising" benzene-ortho-sulpho carboxylic acid, for which
purpose the benzene ortho-sulpho-carboxy-dichloride must be used (see the
Berichte der Deutschen Chemischen Gesellschaft, Volume 12, page 473).

page_text: The process of converting benzamide-ortho-sulphonic acid, or salts thereof, into
saccharin, in general terms, consists in treating the alkaline salts of the benzamide-
ortho-sulphonic acid with phosphorus oxychloride (or agents acting in a similar
manner, such as phosphorus penta-chloride or the like), converting the benzamide-
ortho-sulphonic-chloride thus produced into the corresponding sulphonic amide, viz.,
benzamide-ortho-sulphonic-amide by a suitable treatment with ammonia or other
agents producing the same result, and subsequently by boiling with alkalies, for
instance; hydrolysing the benzamide group contained in the aforementioned
benzamide-ortho-sulphonic amide; finally precipitating the saccharin by acidulating
with acids, or in any other suitable manner.
This new process; in comparison with the known process which must here be
taken into consideration, in which benzene-ortho-sulphonic-carboxylic acid is used
initially, possesses the following advantages:
--
1) Benzamide-ortho-sulphonic-chloride is readily formed, even by means of
phosphorus oxychloride, whereas the conversion of benzene ortho sulphonic
carboxylic acid into benzene ortho sulphonic carboxylic dichloride necessitates the
use of phosphorus pentachloride, the use of which ou a large scale is attended
with considerable difficulty.
2) The conversion of benzamide ortho sulphonic acid into benzamido ortho
sulphonic chloride is effected by means of a molecular proportion of phosphorus
oxychloride, whilst 2 molecular proportions of phosphorus pentachloride are
necessary to convert benzene ortho sulphonic carboxylic acid into the dichloride,
as in this case the hydroxy group of the carboxylic group must also be displaced
by chlorine.
3) Benzamide ortho sulphonic chloride, owing to its greater stability can be
transformed into benzamide ortho sulphonic amide by means of aqueous ammonia,
whilst the benzene ortho sulphonic carboxylic dichloride is but partially converted
into the sulphonic amide by this agent, and therefore ammonia gas or ammonium
carbonate is necessary to effect the conversion.
In view of these advantages, it is immaterial that the new process herein before
defined starts from benzamide ortho sulphonic acid, particularly as but a relatively
small quantity of the cheap ammonia sulpho cyanate is required to produce this
benzamide-ortho-sulphonic acid.
In order to illustrate the new process, the following typical example is given..
CONVERSION OF BENZAMIDE-ORTHO-SULPHONIC ACID INTO BENZOIC
SULPHIMIDE (SACCHARIN).
A mixture of 500 parts of benzamide ortho-sulphonate of potassium and 500 parts-
of phosphorus oxychloride, is heated during 2 hours in a vessel provided with a
reflux condenser. The phosphorus oxychloride present in excess is then distilled
off. After pulverizing the solid mass, it is treated with cold water, and the
benzamide-ortho-sulphonic chloride, which remains in the form of a white crystalline
powder, insoluble in water, is filtered off. It is gradually introduced into 500 parts
of ammonia solution (containing 20 per cent. of pure ammonia), kept cool by means
of ice. The liquid mixture is afterwards heated during a short time on a water-
bath. The benzamide-ortho-sulphonie chloride is thus entirely converted into the
benzamide-ortho-sulphonic amide, which forms a heavy white crystalline powder.
In order to hydrolyse the benzamide group, the benzamide sulphonic amide is
boiled during, say, 4 hours with about five times its weight of soda-lye (containing
4 per cent. of sodium hydroxide). Finally, the saccharine is precipitated by adding
mineral acids to the alkaline liquid, or in any other suitable manner.
In order to convert benzamide ortho sulphonic acid, or its salts, into the
hereinbefore mentioned intermediate products, and finally into saccharin, my
foreign correspondents do not limit themselves to the particulars given in the

page_text: foregoing Example B. The directions can be varied. For instance, the pro-
portions of the ingredients used can vary within certain limits; in place of the
phosphorus oxychloride used other agents acting in the like or a similar manner
(such as phosphorus pentachloride or the like) can be taken; stronger or weaker
ammonia solutions may be used in place of the ammonia solution herein specified, and
containing 20 per cent. of pure ammonia; or instead of the ammonia solution,
other agents capable of producing the same effect (such as ammonia gas, in which
case closed vessels are requisite, or ammonium carbonate or the like) may be used.
Such or similar modifications do not alter this part of the present invention.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed (as communicated to me
from abroad), I declare that what I claim is :-
1. The production of benzamide ortho sulphonic acid from benzene ortho sulpho
carboxylic acid.
2. The process for producing benzamide ortho sulphonic acid, which process
consists in fusing at elevated temperatures benzene ortho sulpho carboxylic acid, or
salts thereof, with ammonium sulphocyanate.
3. The conversion of benzamide ortho sulphonic salts into benzamide ortho
sulphonic chloride.
4. The process for producing benzamide ortho sulphonic chloride, which process
consists in heating benzamide ortho sulphonic salts with phosphorus oxychloride,
or the like agents, acting in the same or a similar manner.
5. The transformation of benzamide ortho sulphonic chloride into benzamide
ortho sulphonic amide, or ortho-sulpho-benzoic diamide.
6. The process for producing benzamide ortho sulphonic amide by allowing
ammonia, or the like agents, to act on benzamide ortho sulphonic chloride.
7. The production of saccharin from benzamide ortho sulphonic amide.
8. The process for producing saccharin, which process consists in hydrolysing
benzamide ortho sulphonic amide by means of alkalies, and subsequently isolating
the saccharin in a suitable manner.
9. The manufacture of benzoic sulphimide (saccharin) from benzamide ortho
sulphonic acid, or from benzamide ortho sulphonic chloride, which process consists
in heating benzamide ortho sulphonic salts with phosphorus oxychloride, or other
agents acting in the same or a similar manner; converting the so formed benzamide
ortho sulphonic chloride by a treatment with ammonia or the like agents into
benzamide ortho sulphonic amide (ortho sulpho benzoic diamide), hydrolysing the
benzamide group contained in the latter product by means of alkalies, and finally
isolating the saccharin by a treatment with mineral acids, or in any other suitable
manner.
10. As new products of manufacture :-
a) Benzamide ortho sulphonic chloride;
b) Benzamide ortho sulphonic amide produced in the manner hereinbefore
defined, or in any other way affording the same result.
בד
31° 00 1 1
CAT
1005
NEWTON & SON,
Agents for the Applicant.