Process for the Production of Dimethyl Ether of Sulphuric Acid.
Year: 1899

page_text: Date of Application, 1st Apr., 1899
Complete Specification Left, 8th Dec., 1899---Accepted, 13th Jan., 1900
PROVISIONAL SPECIFICATION.
Process for the Production of Dimethyl Ether of Sulphuric Acid.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
in the County of London, Consulting Engineer and Chartered Patent Agent, do
hereby declare the nature of this invention (as communicated to me from abroad by
Actien Gesellschaft für Anilin Fabrikation, of Berlin, in the Empire of Germany,
Chemical Manufacturers) to be as follows:-
IL
was first obtained by Dumas and Peligot in connection with their fundamental
researches on methyl alcohol (compare Annales de Chimie et de Physique (2) 58, 32).
The same compound was later on prepared by Claesson and Lundvall (Compare
Berichte der deutschen chemischen Gesellschaft XIII, 1669) by distillation in vacuo
of anhydrous methyl sulphuric acid.
Dumas and Peligot have already stated that the dimethyl ether of sulphuric acid
is readily decomposed by the action of water or alkalies, one methyl group being
split off and methyl sulphuric acid being formed by this treatment. This property
indicates that dimethyl sulphate could be used for methylating phenols etc. Dumas
and Peligot have indeed obtained the methyl ether of benzoic acid by treating
potassium benzoate with the said dimethyl ether of sulphuric acid. The use of this
ether as a methylating agent would be of great advantage, as its boiling point is as
high as 188° C., and therefore methylisation by means of this agent could be
performed in open vessels, whereas in using methyl-chloride or salts of methyl
sulphuric acid, closed vessels are required. On the other hand it would be of
advantage to substitute for the expensive methyl iodide the methyl ether of sulphuric
acid if only it could be produced at a reasonably cheap price. The dimethyl ether
would moreover have that advantage in comparison with the salts of methyl sulphuric
acid that it contains in one molecule two methyl groups which under favourable
conditions can both be eliminated.
Up to the present time however the dimethyl ether of sulphuric acid has never
been used industrially because the methods for its production hitherto known give
only a very bad yield and are much too expensive and complicated.
My correspondents have now discovered a new process for the production of
dimethyl sulphate giving a much better yield of the product and being effected
without any complicated operations. This process is based on the observation that
the dimethyl ether of sulphuric acid is very easily obtained by treating methyl
alcohol with fuming sulphuric acid and thereupon distilling the product of the
reaction in vacuo. This observation is the more unexpected as Müller, (Berichte der
deutschen Chemischen Gesellschaft VI, 1031) has found that by the action of fuming
sulphuric acid on methyl alcohol oxymethane sulphonic acid,

page_text: is formed. My foreign correspondents have found that this different result obtained
by Müller is caused by his working at a more elevated temperature. Under these
conditions the dimethylether of sulphuric acid formed is decomposed again, especially
during the distillation of the reaction product under ordinary pressure, by the action
of the excess of the sulphuric acid, the sulphonic acid above mentioned, methyl
ether (CH3)2O and other bye-products being formed. If however these unfavourable
conditions are avoided and if the dimethyl sulphate is removed from the reaction
product at the lowest possible temperature the process yields a quite different result
from that obtained by Müller and gives a very good yield of the pure dimethyl ether
of sulphuric acid.
The new process is illustrated by the following example:
400 kilos. of fuming sulphuric acid containing 25 per cent. of anhydride are mixed
with 100 kilos. of methyl alcohol, while stirring well, care being taken to keep the
temperature at from 30° to 40° C. The product of the reaction is then distilled off
in vacuo at 20 mm. pressure. The dimethyl ether of sulphuric acid which is distilled
over is washed with a diluted sodium carbonate solution and can, if desirable, be once
more distilled in vacuo.
The properties of the product thus obtained are the same as described by the above
named investigators for the dimethyl ether of sulphuric acid prepared by them by
other methods.
L
14 dow of Anvil 1900
ABEL & IMRAY,
Agents for the Applicant.
Process for the Production of Dimethyl Ether of Sulphuric Acid.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chainbers, Southampton Buildings,
in the County of London, Consulting Engineer and Chartered Patent Agent, do
hereby declare the nature of this invention (as communicated to me from abroad by
Actien Gesellschaft für Anilin Fabrikation, of Berlin, in the Empire of Germany,
Chemical Manufacturers) and in what manner the same is to be performed to be a
particularly described and ascertained in and by the following statement :--
The dimethyl ether of sulphuric acid
was first obtained by Dumas and Peligot in connection with their fundamental
researches on methyl alcohol (compare Annales de Chimie et de Physique
(2) 58, 32).
The same compound was later on prepared by Claesson and Lundvall (compare
Berichte der deutschen chemischen Geselichaft XIII, 1669) by distillation in vacuo
of anhydrous methyl sulphuric acid.
Dumas and Peligot have already stated that the dimethyl ether of sulphuric acid is
readily decomposed by the action of water or alkalies, one methyl group being split
This property
off and methyl sulphuric acid being formed by this treatment.
Dumas
indicates that dimethyl sulphate could be used for methylating phenols etc.
and Peligot have indeed obtained the methyl ether of benzoic acid by treating
The use of this
potassium benzoate with the said dimethyl ether of sulphuric acid.
ether as a methylating agent would be of great advantage as its boiling point is as
high as 180° C., and therefore methylisation by means of this agent could be per-
formed in open vessels, whereas in using methyl-chloride or salts of methyl sulphuric

page_text: acid, closed vessels are required. On the other hand it would be of advantage to
substitute for the expensive methyl iodide the methyl ether of sulphuric acid if only
it could be produced at a reasonably cheap price. The dimethyl ether would moreover
have that advantage in comparison with the salts of methyl sulphuric acid that it
contains in one molecule two methyl groups which under favourable conditions can
both be eliminated.
Up to the present time however the dimethyl ether of sulphuric acid has never
been used industrially because the methods for its production hitherto known give
only a very bad yield and are much too expensive and complicated.
My correspondents have now discovered a new process for the production of
dimethyl sulphate giving a much better yield of the product and being effected
without any complicated operations. This process is based on the observation that
the dimethyl ether of sulphuric acid is very easily obtained by treating methyl alcohol
with fuming sulphuric acid and thereupon distilling the product of the reaction in
vacuo. This observation is the more unexpected as Müller, (Berichte der deutschen
Chemischen Gesellschaft VI, 1031) has found that by the action of funning sulphuric
acid on methyl alcohol oxymethane sulphonic acid
SO₂H
is formed. My foreign correspondents have found that this different result obtained
by Miller is caused by his working at a more elevated temperature.
Under these conditions the dimethyl ether of sulphuric acid formed is decomposed
again, especially during the distillation of the reaction product under ordinary pressure,
by the action of the excess of the sulphuric acid, the sulphonic acid above mentioned,
methyl ether (CH), and other bye-products being formed.
If however these unfavourable conditions are avoided and if the dimethyl sulphate
is removed from the reaction product at the lowest possible temperature the process
yields a quite different result from that obtained by Müller and gives a very good
yield of the pure dimethyl ether of sulphuric acid.
The new process is illustrated by the following example :-
400 kilos. of fuming sulphuric acid containing 25 per cent, of anhydride are mixed
with 100 kilos. of methyl alcohol, while stirring well, care being taken to keep the
temperature at from 30° to 40° C. The product of the reaction is then distilled off
in vacuo at 2 m.m. pressure. The diamethyl ether of sulphuric acid which is
distilled over is washed with a diluted sodium carbonate solution and can, if
desireable, be once more distilled in vacuo.
The properties of the product thus obtained are the same as described by the above
nained investigators for the dimethyl ether of sulphuric acid prepared by them by
other methods.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what I
claim is:
The herein described manufacture of dimethyl ether of sulphuric acid by allowing
fuming sulphuric acid to act at moderate temperature such as 30° to 40° C. on
methyl alcohol and distilling the product of the reaction in vacuo.
Dated this oth does
when 1000
ABEL & IMRAY,
Agents for the Applicant.