Improvements in the Treatment or Purification of Commercial Toluol-sulpho-amide.
Year: 1894

page_text: Date of Application, 27th Mar., 1894
Complete Specification Left, 26th Oct., 1894-Accepted, 1st Dec., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Treatment or Purification of Commercial
Toluol-sulpho-amide.
I, BENJAMIN WILLCOX, of 47 Lincoln's Inn Fields, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by the Firm of Dr. F. von Heyden
Nachfolger of Radebeul near Dresden in the Empire of Germany) to be as
follows:-
Commercial toluol-sulpho-amide consists mainly of ortho and para-amide.
Up to the present time, only one of these substances namely the ortho-amide has
been of commercial value, that is to say as the initial material for the manufacture
of ortho-benzo-sulpho-imide (saccharine).
In this manufacture the para-amide is merely ballast which is not only superfluous,
but also greatly increases the cost of manufacture by reason of the increased
consumption of oxydizing agents, because, whereas the ortho-toluol-sulpho-amide
becomes oxidized to form the sweet benzoe-sulpho-imide, the para-amide is at the
same time oxidized to form the sour para-sulphamine-benzoic acid.
The new method according to this invention of separating para-amide from
mixtures of the two isomeres, is based on the fact that these amides are capable of
forming solid crystallized salts of the alkalies, and that the ortho-salts are less
soluble than the para-salts.
I will now proceed to describe this invention by the aid of the following
examples.
The melting point of pure ortho-amide is from 155° to 156° Centigrade and the
melting point of pure para-amide is 137° Centigrade. Mixtures have of course a
lower melting point.
EXAMPLES.
1. 34 kilogs. of a mixture of coloured toluol-sulpho-amide having a melting point
of from 125° to 139° Centigrade are dissolved cold in 12 litres of soda lye or
solution (105 litres of the soda lye contain 80 kilogs. of caustic soda and 50 litres
of water). After a short time crystallization commences.
After standing for several days the crystallized portion is separated from the
liquid mother liquor B by any suitable means for instance by decantation or by
centrifugal action.
There is thus obtained an almost white mass of crystals of toluol-sulpho-amide
of sodium, which readily dissolves in cold water, and which when precipitated by
acids, yields 10 kilogs. of white purified toluol-sulpho-amide having a melting
point of from 152° to 155° Centigrade. The mother liquor B contains almost all
the coloring matters of the raw amide mixture, and, when (acidulated, yields
22 kilogs. of colored waste or residual amide having a melting point of about
125 Centigrade.
2. 34 kilogs. of coloured toluol-sulpho-amide having a melting point of from
120° to 138° Centigrade are dissolved cold in 40 litres of soda lye containing
8 kilogs. of caustic soda. After standing for several days the crystallized
sodium salt is separated from the mother liquor, is dissolved in cold water and is
acidulated. There results about 12 kilogs. of purified, slightly colored amide
having a melting point of from 150° to 156° Centigrade, whilst from the salt that

page_text: has remained liquid, there is obtained, by acidulation, 20 kilogs. of coloured waste
or residual amide having a melting point of from 115° to 133° Centigrade.
3. 34 kilogs. of amide having a melting point of from 120° to 137° Centigrade
are dissolved in 37.5 litres of soda lye, containing 8.2 kilogs. of caustic soda, and
there results 14 kilogs. of purified slightly coloured amide having a melting point
of from 144° to 156° Centigrade and 17.5 kilogs. of coloured waste or residual
amide having a melting point of from 106° to 118° Centigrade.
4. 34 kilogs. of amide having a melting point of from 126° to 128° Centigrade
are dissolved in cold soda lye of 35.5 litres of water and 8.2 kilogs. of caustic soda.
The results are:
16 kilogs. of purified slightly coloured amide having a melting point of from
138° to 150° Centigrade and 16.8 kilogs. of coloured waste or residual amide
having a melting point of from 115° to 135° Centigrade.
The waste or residual amide may be subjected again to the same process of
purification, because in most cases it still contains considerable quantities of
ortho-amide.
Of course this purifying process will only be continued so long as it is
commercially profitable. In other words, the separation will have to be carried
out in such a manner that the loss accruing through the ortho-amide still
remaining in the residual amide shall be at least covered or balanced by the saving
effected by the absence of the separated portion of para-amide in the further
conversion of the purified amide into saccharine, consequently, before subjecting a
large amount of raw amide to the purifying process, a number of small preliminary
experiments should be made in order to ascertain in such special case the most
favorable ratio of amide to H,O and NaOH. Hydrated oxide of potassium is
much less suitable than the hydrated oxide of sodium.
Dated the 27th day of March 1894.
Improvements in the Treatment or Purification of Commercial
Toluol-sulpho-amide.
1, BENJAMIN WILLCOX of 47 Lincoln's Inn Fields in the County of London
Patent Agent do hereby declare the nature of this invention (which has been
communicated to me from abroad by Dr. F. von Heyden Nachfolger of Radebeul
near Dresden in the Empire of Germany) and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement :-
Commercial toluol-sulpho-amide consists mainly of ortho and para amide. Up
to the present time only one of these substances, namely the ortho amide has been
of commercial value that is to say as the initial material for the manufacture of
ortho benzo-sulpho imide (saccharine).
In this manufacture the para amide is merely ballast which is not only superfluous
but also greatly increases the cost of manufacture by reason of the increased
consumption of oxidizing agents, because whereas the ortho-toluol-sulpho amide
becomes oxidized to form the sweet benzo sulpho-imide, the para-amide is at the
same time oxidized to form the sour para-sulphamine benzoic acid.
The new method according to this invention of separating para-amide from
mixtures of the two isomeres is based on the fact that these amides are capable of
forming solid crystallized salts of the alkalies, and that the ortho-salts are less
soluble than the para salts.
I will now proceed to describe this invention by the aid of the following
examples.
The melting point of pure ortho amide is from 155° to 156° Centigrade and the

page_text: MAAMPLES.
1. 34 kilogs. of a mixture of coloured toluol sulpho amide having a melting
point of from 125° to 139° Centigrade are dissolved cold in 12 litres of soda lye or
solution (105 litres of the soda lye contain 80 kilogs. of caustic soda and 50 litres
of water. After a short time crystallization commences.
After standing for several days the crystallized portion is separated from the
liquid mother liquor B by any suitable means for instance by decantation or by
centrifugal action.
There is thus obtained an almost white mass of crystals of toluol-sulpho-amide of
sodium, which readily dissolves in cold water, and which when precipitated by acids,
yields 10 kilogs. of white purified toluol-sulpho-amide having a melting point of
from 152° to 155° Centigrade. The mother liquor B contains almost all the
colouring matters of the raw amide mixture, and when acidulated yields. 22 kilogs.
of coloured waste or residual amide having a melting point of about 125° Centigrade.
2. 34 kilogs. of coloured toluol-sulpho-amide having a melting point of from
120° to 138° Centigrade are dissolved cold in 40 litres of soda lye containing
8 kilogs. of caustic soda.
After standing for several days the crystallized sodium salt is separated from
the mother liquor, is dissolved in cold water and is acidulated. There results
about 12 kilogs. of purified, slightly coloured amide having a melting point of
from 150° to 156° Centigrade, whilst from the salt that has remained liquid, there
is obtained, by acidulation 20 kilogs. of coloured waste or residual amide having a
melting point of from 115° to 133° Centigrade.
3. 34 kilogs. of amide having a melting point of from 120° to 137° Centigrade
are dissolved in 37.5 litres of soda lye containing 8.2 kilogs. of caustic soda and
there results 14 kilogs. of purified slightly coloured amide having a melting point
of from 144° to 156° Centigrade and 17.5 kilogs. of coloured waste or residual
amide having a melting point of from 106° to 118 Centigrade.
4. 34 kilogs. of amide having a melting point of from 126° to 128° Centigrade
are dissolved in cold soda lye of 35.5 litres of water and 8-2 kilogs. of caustic soda.
The results are:-16 kilogs. of purified slightly coloured amide having a melting
point of from 138° to 150° Centigrade and 16-8 kilogs. of coloured waste or
residual amide having a melting point of from 115° to 135° Centigrade.
The waste or residual amide may be subjected again to the same process of
purification, because in most cases it still contains considerable quantities of
ortho-amide.
Of course this purifying process will only be continued so long as it is commercially
profitable.
In other words the separation will have to be carried out in such a manner that
the loss accruing through the ortho-amide still remaining in the residual amide
shall be at least covered or balanced by the saving effected by the absence of the
separated portion of para-amide in the further conversion of the purified amide
into saccharine. Consequently, before subjecting a large amount of raw amide to
the purifying process, a number of small preliminary experiments should be made
in order to ascertain in such special case the most favourable ratio of amide
to H₂O and NaOH.
Hydrated oxide of potassium is much less suitable than the hydrated oxide of
sodium.
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 separating para toluol-sulpho-amide from mixtures thereof with

page_text: ortho-toluol-sulpho-amide by partial crystallization of the alkali salts preferably of
the sodium salts of toluol-sulpho-amide substantially as herein before described.
Dated the 26th day of October 1894.
JOHNSONS & WILLCOX,
Agents.