Process for the Production of Orthotoluolsulpho Acid from Ortho- thiocresol by Oxidation with the Aid of Concentrated Nitric Acid.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Process for the Production of Orthotoluolsulpho Acid from Ortho-
thiocresol by Oxidation with the Aid of Concentrated Nitric
Acid.
I, Dr. FRITZ HAUFF, of Feuerbach, near Stuttgart, Germany, Manufacturer, do
hereby declare the nature of this invention to be as follows:-
In the method of producing orthotoluolsulpho acid described in the Specification
of the British Patent No. 10810 of 1897 mention is made of permanganate
of potassium as the oxidizing agent. Although as regards the yield and purity of
the product thus obtained, the results are satisfactory, the process still labours under
disadvantages that the oxidizing agent is expensive, its re-generation associated
with considerable outlay for plant, and that in consequence of the extensive dilution of
the dissolvent, large quantities of water must be evaporated in order to arrive at a
suitable dry material for the further saccharine manufacture. These disadvantages
are all obviated if nitric acid be employed as the oxidizing agent instead of
manganate of potassium. As product of reduction of the nitric acid, nitrous gas
results, and which, by the aid of the atmospheric oxygen can easily be re-con-
verted into nitric acid.
per-
The necessary surplus of nitric acid for a complete re-action can be completely
recovered by distillation, so that if suitable apparatus be employed in working, the
outlay for the oxidizing agent (nitric acid) is quite unimportant. In this way, it is
possible to produce an exceedingly cheap and pure preliminary or working product
for the purposes of the saccharine manufacture.
The oxidation proceeds according to the following equation:

page_text: The following has proved to be the best recipe:
Orthothiocresol
12 kilogrammes
Contents of the stone pot, into which the thiocresol and the concentrated nitric
acid uniformly flow :
Nitric acid (60%)
Nitric acid (95%)
Simultaneously flowing in with the thicresol
Nitric acid (95%)
-
Temperature 30-40° Celsius
3 kilogrammes
2 kilogrammes
20 kilogrammes
After the contents of the pot have been entirely freed from the superfluous acid
by free distillation in vacuo, it is poured into a little water whereby a small quantity
of disulphide, which appears as a by-product, is separated, then neutralised wit
soda, dried by steam, and at once further prepared as orthotoluolsulphochloride
orthotoluolsulfamid, and finally as saccharine.
Process for the Production of Orthotoluolsulpho Acid from Ortho-
thiocresol by Oxidation with the Aid of Concentrated Nitric
Acid.
I, Dr. FRITZ HAUFF, of Feuerbach, near Stuttgart, Germany, Manufacturer, 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 method of producing orthotoluolsulpho acid described in the Specification
of the British Patent No. 10810 of 1897, mention is made of permanganate of
potassium as the oxydizing agent. Although as regards the yield and purity of
the product thus obtained, the results are satisfactory, the process still labours
under the disadvantages that the oxydizing agent is expensive, its re-generation
associated with considerable outlay for plant, and that in consequence of the
extensive dilution of the dissolvent, large quantities of water must be evaporated in
order to arrive at a suitable dry material for the manufacture of saccharine. These
disadvantages are all obviated if nitric acid be employed as the oxydizing agent
instead of permanganate of potassium.
As product of reduction of the nitric acid, nitrous gas results, and which by the
aid of the atmospheric oxygen can be easily re-converted into nitric acid. The
necessary surplus of nitric acid for a complete re-action can be completely recovered
by distillation, so that if suitable apparatus be employed in working, the outlay for
the oxydizing agent (nitric acid) is quite unimportant. In this way, it is possible to
produce an exceedingly cheap and pure initial or raw product for the purposes of
the saccharine manufacture.

page_text: The clear watery solution of the ortho-toluolsulpho-acid is now neutralised by
soda and then evaporated till dryness, whereby the natron salt of the ortho-
toluolsulpho-acid is obtained, which according to known methods by means of
phosphorus-pentachloride is oxidised into ortho-toluolsulpho-chloride, then the latter
with watery ammonia is oxidised into orthotoluolsulfamid and finally the said
sulfamid by oxidation with permanganate of potassium is oxidised into
saccharine.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
The process for the production of ortho-toluolsulpho acid from orthothiocresol by
oxidation with the aid of concentrated nitric acid substantially as described.
ms
H. GARDNER,
Patent Agent, 166, Fleet Street, London.
Agent for the said :-
DR. FRITZ HAUFF.