Improvements in the Manufacture of Salicylic Acid Esters
Year: 1886

page_text: Date of Application, 16th June, 1886.
Complete Left, 16th Mar., 1887.
. Complete Accepted, 22nd Apr., 1887.
Improvements in the Manufacture of Salicylic Acid Esters."
We, MARCEL VON NENCKI of Bern Switzerland, Professor and Doctor of
Philosophy and Dr. CARL KOLBE, doing business under the style of Dr. F. von
Heyden Nachfolger of Radebeul near Dresden, Saxony, in the Empire of Germany,
do hereby declare the nature of this invention to be as follows :-
Acids of the fat series and of the aromatic compounds give with phenols, when
heated alone or when treated with dehydrating substances (such as sulphuric acid,
zinc chloride, stannic chloride, aluminium chloride,) ketons with separation of water.
For example if acetic acid be heated together with resorcin and zinc chloride,
resacetophenol is formed, (Journal für prakt Chemie, vol 23, page 147, 1881).
On heating salicylic acid with resorcin for several hours at 195-200°, A. Michael
obtained salicylic acid resorcin keton, and he obtained salicylic phenyl keton when
treating salicylic acid and phenol with stannic chloride, (Berichte der Deutschen
chem. Gesellschaft 1881, pg. 658).
Now we have discovered that when fatty or aromatic acids are heated with phenols
and naphthols in the presence of phosphoric oxychloride as a dehydrating agent, not
ketons but acid esters are formed.
For instance on fusing together equivalent amounts of salicylic acid and phenol,
and heating the mixture with phosphoric oxychloride to 120-130°, we obtain
salicylic acid phenylester CH-CO
-0 H-0-C, H,
a crystallizable body, with a
melting point of 43°. A thorough study of the chemical changes that take place,
has shown that in this reaction, two molecules of acid, two molecules of phenol,
and one molecule of phosphoric oxychloride combine according to the equation
(
06 H
6
-O H
$ CO-OH
+ 2 (С H¸−O H) + P. O CI, (phosphoric oxychloride)=

page_text: and not 3 molecules of acid, 3 molecules of phenol and 1 molecule of phosphoric
oxychloride, in which case ordinary phosphoric acid (H, PO) would be produced
according to the equation
There can be formed under the same conditions as above, from salicylic acid
and resorcin, salicylic acid-resorcin-
C₁ H₁
-
CO-CH-OH
0 со CH
-
он
a crystallizable substance, soluble in alcohol and ether, not soluble in water, and
whose melting point is 111°. On treating salicylic acid with alpha- and beta-
naphthol, bioxynaphthalin (melting point 186°) etc, combinations are formed which
are colourless, crystallizable, not soluble in water, but easily soluble in alcohol, ether,
benzol, "ligroin" etc.
Further experiments have shown
*
22
1. That if this metaphosphoric acid that is formed in the above process, and
that causes the formation of large quantities of phosphoric acid phenyl esters
be combined with a metal, then the whole-reaction works more smoothly and gives
better results. This condition is easily fulfilled if instead of free salicylic acid
and phenol, sodium compounds or other metallic salts of the same are used, as
represented in the two following equations:
2
-
он
06 H O. Na.)
(o
·
2. C. Hi
or 2
2.
-
-
CO
он
-
-
+ 2 (C, H, OH) + P. O. Cl, =
COO.- C H¸.
(C, H.-H
=
+Na P. O, + Na Cl +2 HCl,
CO- O Na +2 (CHO Na) + P. O. Cl₂ =
OH
(CH-000-CH) + Na PO₁ + 3 (Na Cl).
2: That instead of phosphoric-oxychloride, phosphoric penta-chloride. may be
employed with the same effect, thus-
a) By, heating together an equivalent of salicylic acid and an equivalent of
OH
phosphoric penta-chloride, by which salicylic chloride (C, H.-00-01), and
phosphoric oxychloride are formed, and afterwards letting two equivalents of salicylic
acid and three equivalents of phenol, act upon this mixture; or
b) By fusing together three equivalents of salicylic acid, three equivalents of
phenol; and one equivalent of phosphoric penta-chloride according to the equation.
3 ( C. H.
+ 3 (C. H. —OH) + P Cl. =
3
C. H
3
+ 3 (C
OH) + PC. =
(% H-00-0-0, H.)₁+ HP O, + 5 (H CI).
In this case also the sodium compounds of salicylic acid and of phenol can be
employed to advantage.
3. That it is not necessary to begin with the free salicylic acid, but the mixture:
obtained-in the manufacture of salicylic acid according to the equation
-
2 (C, H, O Na) + CO₂ = CH;
O Na
CO O Na + C, H, OH
may be used, if it be treated after it has cooled somewhat, with phosphoric oxychloride
or phosphoric penta-chloride, which process may be represented by the equation
(CHO Na) + 2(Ü O₂) +PO (1,
=======
6
- CO - 0 - % H₂) + Na PO¿ + 3 (Na Cl).
3

page_text: The same process may be employed if carbonic acid phenyl "ester
C₁ H
0 CH
como
-
33
be used thus a mixture of carbonic acid phenyl ester," sodic hydrate, and phenol
is heated for some time at 180-200°, preferably in a closed apparatus. It is then
left to cool a little and then treated, as above, with phosphoric oxychloride or
phosphoric penta-chloride.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Salicylic Acid "Esters."
We, MARCEL VON NENCKI, of Bern, Switzerland, Professor and Doctor of
Philosophy, and Dr. CARL KOLBE, doing business under the style of Dr. F. von
Heyden, Nachfolger, of Radebeul near Dresden, Saxony, in the Empire of Germany,
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
Acids of the fat series and of the aromatic compounds give with phenols, when
heated alone or when treated with dehydrating substances (such as sulphuric acid,
zine chloride, stannic chloride, aluminium chloride.) ketons with separation of water.
For example if acetic acid be heated together with resorcin and zinc chloride,
resacetonaphton is formed. (Journal für prakt. Chemic. vol. 23, page 147, 1881.)
On heating salicylic acid with resorcin for several hours at 195-200° C, A. Michael
obtained salicylic acid resorcin keton, and he obtained salicylic phenyl keton
when treating salicylic acid and phenol with stannic chloride. (Berichte der
Deutschen chem. Gesellschaft 1881, pg. 658.)
Now we have discovered that when fatty or aromatic acids are heated with phenols
and naphthols in the presence of phosphoric oxychloride as a dehydrating agent,
not ketons but acid esters are formed.
For instance on fusing together equivalent amounts of salicylic acid and phenol,
and heating the mixture with phosphoric oxychloride to 120-130° C, we obtain
22
он
salicylic acid phenyl “ester ” C H со 0-CH
1
a crystallizable body, with
a melting point of 43° C. A thorough study of the chemical changes that take place,
has shown that in ths re-action, two molecules of acid, two molecules of phenol, and
one molecule of phosphoric oxychloride combine according to the equation :
H₁_ CO-OH
Salicylic acid
Phenol
2
(C. H
-
O H
CO-0 C, H,
C. H.)
+ H. P. O3
Salicylic-acid Phenyl ester
Metaphosphoric acid
(phosphoric oxychloride)= 2
+
3 H. Cl.
Hydrochloric acid
and not three molecules of acid, three molecules of phenol, and one molecule of
phosphoric oxychloride, in which case ordinary phosphoric acid (H, P O₁) would 3
be produced according to the equation
OH

page_text: There can be formed under the same conditions as above, from salicylic acid and
resorcin, salicylic acid-resorcin-ester
-
CH
0-00-C, H. - OH
CH OH
:
a crystallizable substance, soluble in alcohol and ether, not soluble in water, and
whose melting point is 110° C. On treating salicylic acid with alpha- and beta-
naphthol, bi-oxynaphthalin (melting point 186° C) etc, combinations are formed
which are colourless, crystallizable, not soluble in water; but easily soluble in alcohol,
ether, benzol, ligroine," etc:
Further experiments have shown
1. That if this metaphosphoric acid that is formed in the above process, and 'that
causes the formation of large quantities of phosphoric acid. phenyl esters be
combined with a metal, then the whole reaction works more smoothly, and gives
better results. This condition is easily fulfilled if instead of free salicylic acid
and phenol, sodium compounds or other metallic-salts of the same are used, as
represented in the two following equations :-
-OH
2 (CH, CO-O Na
-
+2 (C, H, OH) + PO Cl., =
1+Na PO3 + Na: Cl. + 2 H Cl.
2
6
or 2
(C, H₂
(C,
1
O.H
coo-
CH
H.-OH
+2 (CH, O Na) + PO Cl., =
CO
он
O Na.)
2 (C, H.-0-0-C. H.) + Na. PO, + 3 (Na. Cl.)
2. That instead of phosphoric oxychloride, phosphoric penta-chloride may be
employed with the same effect, thus:
(a) By heating together an equivalent of salicylic acid and an equivalent of
phosphoric penta-chloride, by which salicylic chloride (C. H -00 - C₁.)
and
phosphoric oxychloride are formed, and afterwards letting two equivalents of salicylic
acid and three equivalents of phenol act upon this mixture; or
(b) By fusing together three equivalents of salicylic acid, three equivalents of
phenol, and one equivalent of phosphoric penta-chloride according to the equation
3
(C₂ H₁
C 11
-
-
- O H
-
CO-OH H) + 3 (C, H.- O H) + P Cl. =
- O H
L 1-1 PO L

page_text: Having now particularly described and ascertained the nature of the said invention,
and in what manner it is to be performed, we declare that what we claim is:―
1. The production of salicylic acid esters by heating salicylic acid and phenol
or napthol with phosphoric pentachloride or phosphoric oxychloride, substantially
as described.
2. The production of salicylic acid esters by fusing together sodium or other
metallic compounds of salicylic acid and phenols or naphthols with phosphoric
pentachloride or phosphoric oxychloride, substantially as described.
3. The production of salicylic acid esters by treating with phosphoric penta-chloride
or phosphoric oxychloride, the specified mixture produced in the manufacture
of salicylic acid substantially as described.
4. The salicylic acid "esters" of phenols and naphthols obtained by either of the
processes referred to in the preceding claims.
Dated this 16th day of Mach 1997