Improvements in the Manufacture of Saccharine, or Compounds thereof, or Mixtures Containing the same, and in the Production and Treatment of Materials for Use therein.
Year: 1896

page_text: Date of Application, 6th Aug., 1896-Accepted, 17th Oct., 1896
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Saccharine, or Compounds
thereof, or Mixtures Containing the same, and in the Production
and Treatment of Materials for Use therein.
I, CONSTANTIN FAHLBERG Doctor of Philosophy of Salbke Westerhüsen near
Magdeburg in the Kingdom of Prussia German Empire Manufacturing Chemist
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:-
In the Specification of Letters Patent No. 10955 of 1895 I have described a
method of separating para-toluene sulphonic acid from ortho-toluene sulphonic:
acid by means of magnesium salts. I have now found by trial and experiment
that by the zinc salts of the two toluene sulphonic acids the separation of the
para-toluene-sulphonic acid from the ortho-toluenesulphonic acid can be effected:
(owing to the former being less soluble than the latter) in nearly the same propor--
tion as in the case of magnesium salts described in the said Specification of
Letters Patent No. 10955 of 1895.
In order to effect the said separation the toluene sulphonic acids resulting from
the treatment of toluene with sulphuric acid are first converted into their calcium
salts and these latter are acted upon by sulphate of zinc in order to produce
calcium sulphate which can be filtered off and the aqueous solution of zinc toluene
sulphonates are evaporated which may be done in the same manner as in the case
of employing the magnesium salts and the sulphonates being allowed to crystallize.
The para zinc toluene sulphonate will crystallize out whereas the ortho zine toluene
sulphonate, with some portion of the para zinc toluene sulphonate which is not
crystallized out, will remain in solution.
The second method of obtaining zinc salts of toluene sulphonic acids is by
treating the said acids with oxide of zinc and the resultant zinc toluene sulphonates,.
are then treated in the manner herein before described.
The portion which is still a mixture of ortho and para toluenesulphonate of zinc
can then be utilised as mentioned in the aforesaid Specification of Letters Patent
No. 10955 of 1895 in the process described therein for the purpose of making
saccharine.
The para zinc toluene sulphonate obtained by crystallization from the above
mixture can be subjected to treatment with sulphuric acid and superheated steam.
in order to regenerate toluene and sulphate of zinc and the latter can be used
over and over again in a cycle for producing fresh quantities of zinc toluene
sulphonates.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In the manufacture or preparation of saccharine or benzoic sulphinide or
compounds or mixtures containing the same the use of oxide of zinc or a salt of
zinc for the purpose of separating the ortho compound from the bulk of the para
compound of toluene sulphonic acids by the formation of zinc salts of those acid
bodies by crystallization as hereinbefore explained.
2. In the manufacture or preparation of saccharine or benzoic sulphinide or
compounds or mixtures containing the same the separation of ortho-toluene

page_text: sulphonic acid from a mixture of ortho-toluene sulphonic acid and para-toluene,
:sulphonic acid, or the salts of these acids, by oxide of zinc, or a salt of zinc
whereby the corresponding sulphonates are formed the bulk of the less soluble
para-toluene sulphonate of zinc being separated from the mixture by crystallization
as hereinbefore explained.
3. The cycle substantially as herein before described in the manufacture or
preparation of saccharine or benzoic sulphinide or mixtures or compounds con-
taining the same by which oxide of zinc or a salt of zinc is used over and over
again as herein before set forth.
Dated this 6th day of August 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.