Improvements in the Manufacture of Saccharine.
Year: 1899

page_text: Date of Application, 29th Sept., 1899
Complete Specification Left, 7th Dec., 1899-Accepted, 13th Jan., 1900
ommunicated from abroad by CHEMICAL WORKS, formerly Sandoz, of Basle, in the
Republic of Switzerland.]
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Saccharine.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, do hereby declare the nature
of this invention to be as follows:-
By oxydizing orthotoluolsulfamide with permanganate in alkaline solution
saccharine is produced as well as varying quantities of orthosulfamidobenzoic acid.
The yield of this byproduct can be increased to a high degree by raising the
percentage of alkali (sodalye) in the solution of the oxydation. Hitherto however no
economical process was known to convert the orthosulfamidobenzoic acid thus formed
into saccharine. It is true, that in "Beilstein's Hanbuch der organischen
Chemie" III edition, II volume page 1295 orthosulfamidobenzoic acid is said to be
transformed completely into saccharine by heating at 180° C. After our researches
however this transformation takes place only to, at the best, 50%, the other part
being converted into the ammoniasalt of the orthosulfobenzoic acid, according to the

page_text: Improvements in the Manufacture of Saccharine.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, do hereby declare the
nature of this invention and in what manner the same is to be pérformed, to be
particularly described and ascertained in and by the following statement :--
By oxidizing orthotoluolsulfamide with permanganate in an alkaline solution,
according to Fahlberg & List, Berichte der deutschen chemischen Gesellschaft,
21, 242, saccharine is produced as well as varying quantities of orthosulfamidobenzoic-
acid.
The yield of this byproduct can be increased to a high degree by raising the
percentage of alkali (sodalye) in the oxidizing solution. By this means slightly
more than the theoretical quantities of permanganate is sufficient for the complete
oxydation of the orthotoluolsulfamide; by an appropriate choice of the degree of
the dilution, the proportions of the alkali and the temperature, the oxydation
process may be carried with nearly quantitative yield to the formation of a mixture
of saccharine and orthosulfamidobenzoic acid, their decomposition into valueless
byproducts as orthosulfobenzoic acid and oxalic acid being almost entirely avoided.
Hitherto however no economical process was known to convert the orthosulfamido-
benzoic acid thus formed into saccharine. It is true, that in "Beilstein's Handbuch
der organischen Chemie" III edition, If volume page 1295 orthosulfamidobenzoic
acid is said to be transformed completely into succharine by heating at 180º.. C:
After our researches however this transformation takes place only to, at the best 50%;
the other part being converted into the ammoniasalt of the orthosulfobenzoic acid,
according to the equation
2 CH
=CH
NH + CHẠ
CO OH
SO
CO OH
By heating the salts of the orthosulfamidobenzoic acid at about 200° C. according
to a note of Fahlberg and Brage, Berichte der deutschen chemischen Gesellschaft,
22,754 the yield of saccharine will be much below 50%.
Now a very economical process for the aforesaid transformation has been discovered,
according to which approximately the theoretical yields are obtained, by treating the
dry orthosulfamidobenzoic acid or its salts with dehydratizing agents such as
chlorsulfonic acid or more economically strong sulfuric acid or fuming sulfuric acid.
By the use of this process i.e. by conducting the oxydation of the orthotoluolsul-
famide first to the orthosulfamidobenzoic acid and afterwards converting this into
saccharine, the latter can be obtained in greater yields and cheaper than by the
methods hitherto known.
The orthosulfamidobenzoic acid being of greater acidity than its anhydrid the
saccharine, and the latter being of greater acidity than the parasulfamidobenzoic
acid the parasaccharine, pure orthosulfamidobenzoic acid can be very readily obtained
from unpurified toluolsulfamide by oxidizing for instance a mixture of about 70-75%
of orthotoluolsulfamide and 25-30% of paratoluolsulfamide in an alkaline solution
(dilute sodalye) with permanganate and boiling the concentrated solution of
saccharine, ortho- and parasulfamidobenzoic acid thus obtained with sodalye until the
whole saccharine is saponified. to orthosulfamidobenzoic acid. The parasaccharine
can be precipitated quantitatively from the resulting solution by adding at a
temperature not exceeding 35° C. while well stirring, dilute mineral acid as for

page_text: instance muriatic acid of 10% until a weak acid reaction on Congopaper takes place.
Under these conditions not a trace of orthosulfamidobenzoic acid is precipitated; the
pure parasaccharine may be filtered out and from the resulting solution pure ortho-
sulfamidobenzoic acid, absolutely free from parasaccharine may be precipitated by a
further addition of mineral acids.
It is then filtered off, washed, dried and is now ready for direct transformation
into pure saccharine 550, melting at 225-227° C.
The improved process may be carried into practice as follows:
40 kilos. of orthosulfamidobenzoic acid are introduced slowly by well stirring into
120 kilos. of fuming sulfuric acid of 20%, care being taken that the temperature
does not exceed 40° C. The clear, slightly yellowish solution thus obtained is now
allowed to stand at the ordinary temperature for about 24 hours; it is then poured
upon a mixture of 300 kilos. of ice and 100 kilos. of water. The precipitation of
saccharine is filtered, washed with cold water and dried. The actual yield thus
obtained is 95% of the theoretical one.
The quantitative result of the transformation is nearly the same, when in the
foregoing example the fuming sulfuric acid is substituted by chlorsulfonic acid,
sulphuric acid monohydrate, or strong sulphuric acid of 66° Bé."
Having now particularly described and ascertained the nature of the said invention
and in what manner the saine is to be performed, as communicated to me by my
foreign correspondent, I declare that what I claim is :-
A process for the manufacture of saccharine, which consists in treating ortho-
sulfamidobenzoic acid or its salts with dehydratizing agents such as fuming sulphuric
acid, chlorsulfonic acid, sulphuric acid monohydrate, or strong sulphuric acid..
Dated this 7th day of December 1899.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.