Year: 1894

page_text: Date of Application, 27th Mar., 1894-Accepted, 12th May, 1894
C₁H, SO, OH + C,H¸OH = C₁H, SO, ОC₂H¸ + HOH;
CH, SO, OC,H + CH₂CO OH = C₁H, SO, OH + CH, CO OC,H¿.
10
1
With the raw aćetic éster produced in continuous working by means of the
sulphonic acid process there are mixed, besides water, alcohol and acetic acid, for
which reason it must be further treated with known reagents; by working
equivalent quantities of alcohol and acid, ethyl ester is formed always in very small
quantity; it can be detected and, if required, removed by distilling the previously
purified acetic ester in the column apparatus.
In exactly the same manner the esters of other acids are obtained; for instance
the butyric acid ethyl ester by adding a mixture of butyric acid and ethyl alcohol
to B-naphthalene sulphonic acid at a temperature of about 115° to 135° C.
For manufacturing esters (or ether) having a higher boiling point, the treatment
may be effected in a partial vacuum, so that the process becomes continuous, liquid
acids are added mixed with alcohols, while solid acids are preferably added
separately. If such substances having a higher boiling point are manufactured
under ordinary pressure, they may be otherwise separated from the reaction mixture
as by distilling.
1

page_text: Benzoic acid for instance is converted into benzoic acid ethyl ester by causing
ethyl alcohol to flow in a little excess at a temperature of 120° to 140° C. through
a mixture of benzoic acid and nearly the same weight of a sulphonic acid.
But the ester which boils at a temperature of 213° C. is then only partly found
in the distillate and the portion remaining in the reaction vessel can be separated
from the cooled reaction mass by adding water, and insulated by removing the
same. After the expulsion of the added water the sulphonic acid may immediately
be employed again.
The advantages of the sulphonic acid process in its above described appli-
cations as compared with the older process with sulphuric acid are based on
the properties of the sulphonic acids explained in the previous Specification above
referred to. There are however other applications of the sulphonic acids.
The sulphonic acids referred to in the beginning of this Specification are more-
over suited for etherification of those compounds, principally aromatic, in which
sulphuric acid cannot be used, because their capability of forming sulphonic acids
acts as a hindrance. In contrast to sulphuric acid, the sulphonic acids act only in
an etherifying manner forming no more sulphonic acids. It is only exceptionally,
and usually only at high temperature, that they hinder the process of etherification
by sulphonic formation.
The numerous carbon acids, not belonging to the class of fatty substances, may
therefore be converted into ethers, exactly in the same way as above described;
also phenols naphthols, diphenols etc. and their homologues and products of substi-
tution; also aromatic alcohols, such as benzylic alcohol, the tolyl alcohols, also
compounds uniting in themselves the functions of these different classes of
substances, such as aromatic oxy-acids, may be converted into ethers in the
same way.
In these and in similar cases where sulphuric acid seems to be inapplicable,
sulphonic acids may be used with more or less advantage in the etherification
process.
Thus, for instance, we obtain from phenol by means of B-naphthalene
sulphonic acid by passing-through methyl alcohol at a temperature of from 120°
to 140°, anisol (CHO CH3), the boiling point of which is 152° C.; by passing
through ethyl-alcohol we obtain the phenetol (CHO C₂H), the boiling point of
which is 172° C.
The liquid methyl ether a-C₁,H,O CH3, the boiling point of which is
about 265° C., is produced from a-naphthol by causing a solution of a-naphthol
in about four times its weight of methylalcohol, to flow through heated sulphonic
acid, such as ẞ-naphthalene sulphonic acid, at a temperature of about 140°
to 145° C. Also diphenols may be completely etherified, for instance resorcine,
which, dissolved in from six to eight times its weight of methylalcohol and
treated in exactly the same manner as the above mentioned solution of the
a-naphthol gives abundant quantities of liquid dimethylether (C.H (OCH₁)2:),
the boiling point of which is about 214° C. and which may easily be separated by
alkalies from the free resorcine or the monomethyl-ether.
But while in the carbon acids by the use of 1 or 2 molecules of the corre-
sponding alcohol a considerable production of esters is obtained, a larger excess of
alcohol is usually necessary for the etherification of the phenols; and while in the
carbon acids, also under less favorable conditions, in addition to the esters the
ethers (say besides the acetic acid ethyl ester the ethyl ether) are produced in
only very small quantities, in addition to phenetol, for instance, the ethyl ether is
easily produced in abundance. But as the ethyl ether can also easily be separated,
its production offers no serious difficulty.
The etherification of the carbon acids being much more easy as compared with
the phenols allows of the preparation by means of sulphonic acids, also of esters
of the oxyacids such as salicylic-acid-ethyl-ester, o-CH(OH)CO,C,H,, the
boiling point of which is about 226° C. This ester is produced by causing a
solution of salicylic acid in ethyl alcohol to flow through ẞ-naphthalene-sulphonic

page_text: acid at a temperature of 145 to 150° C.; the product is purified in the same.
manner as the benzoic ester above described.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what.
we claim is :-
1. The application of the process described in the Specification No. 21938.
of 1892 to the manufacture of compound ethers, acid esters by the combined
action of alcohols and acids, preferably at temperatures above 100° C. on suitable
sulphonic acids, particularly those of the aromatic series, substantially as
forth.
set.
2. The modification of the process by causing acids to act, preferably at tem-
peratures above 100° C., on esters of suitable sulphonic acids, particularly on those
of aromatic sulphonic acids, substantially as set forth.
3. The application of the process described in the Specification No. 21938 of
1892 for etherifying or esterifying phenols or naphthols and the products of sub-
stitution of the same, by causing phenols or naphtols to act either mixed with
alcohols or alone, preferably at temperatures above 100° C., on suitable sulphonic
acids, particularly those of the aromatic series, or on the esters of those sulphonic
acids, substantially as set forth.
4. The application of the sulphonic acid process for the etherification or
esterification of organic substances, when sulphuric acid cannot be used owing
to by-reactions causing hindrance particularly by formation of sulphonic acids,.
substantially as described.
Dated this 27th day of March 1894.
ABEL & IMRAY,
Agents for Applicants.