Year: 1892

page_text: Date of Application, 30th Nov., 1892-Accepted, 11th Feb., 1893

page_text: Notwithstanding the surprising resemblance of this process of producing ether,
with the method already in use for centuries and appearing no further susceptible
of improvement and consisting in preparing ether from sulphuric acid and alcohol
or strong spirit of wine, the new method offers, in comparison with this older.
and practically imperfect process, quite remarkable advantages.
:
As is commonly known, sulphuric acid is rather easily decomposed by heat
owing to oxidising processes in forming sulphurous acid, moreover sulphuric
acid retains at the temperature of reaction a larger quantity of water than is
suitable for the process of producing ether in the old process the operation had
therefore to be interrupted as soon as a relatively small quantity of alcohol
was added to the sulphuric acid. The sulphonic acids (in which the unstable
hydroxyl group of free sulphuric acid which is useless for the process of pro-
ducing ether is substituted by a negative radical bound to the sulphonic group)
differ from the sulphuric acid by a steadiness highly remarkable for the actual
purpose at the temperature of reaction with respect to the alcohol susceptible of
oxidation; moreover at the temperature of reaction sulphonic acids give off the
water far more easily than sulphuric acid; a mixture of sulphonic acid and alcohol
may therefore be maintained in a boiling state for days while continuously adding
alcohol without perceiving any notable alteration in the composition of the reaction
mixture as well as of the distillate. Small quantities of some sulphonic acid
esters are slowly taken along, it is true, by the superheated vapours, but the free
sulphonic acid can be recovered without any loss from the distillate after the
removal of the ether and alcohol by simple evaporation. Benzene-sulphonic acid
can in this manner convert, as has been proved by experiment, more than one
hundred times its weight of ethyl alcohol into ethyl ether.
The new process is distinguished from the old one not only by greater
simplicity and continuity of working-whereby the initial higher price of the
sulphonic acid in comparison with that of the sulphuric acid is largely compensated
-but also by the greater purity of the ether produced.
If to a suitably heated sulphonic acid, say, to benzene-sulphonic acid at a
temperature of about 150° C., methyl alcohol is added, the gaseous methyl ether
CH O Ch, escapes in a regular current. In the same way propyl ether
C.H, O C.H, may advantageously be obtained directly from benzene-sulphonic
acid and propyl alcohol at about 130° C. Per contra for alcohols having a
higher molecular weight it is advisable, on account of the less ready decom-
posibility of the sulphonic acid esters, to prepare the latter in a pure state prior
to the production of ethers.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is,―
1. A process of preparing simple ethers especially methyl ether ethyl ether and
their homologues and also mixed ethers such as methyl-ethyl-ether by the action of
methyl alcohol ethyl alcohol and their homologues on benzene-sulphonic acid
benzene disulphonic acid p-toluene-sulphonic acid B-naphtalene-sulphonic acid and
other sulphonic acids which by their steadiness and other properties are adapted
therefore substantially as set forth.
2. The process for preparing the ethers mentioned in the first claim by the action
of alcohols on the esters of sulphonic acids substantially as set forth.
Dated this 30th day of November 1809
W. P. THOMPSON & BOULT,
Agents for the Applicants.
W. P. THOMPSON & BOULT,
Agents for the Applicants.