Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
372
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K 5732
PROCESS FOR THE PREPARATION OF SULPHURIZED SALICYLATES
This invention relat~s to a process for the preparation of
sulphurized, optionally overbased metal aliphatic hydrocarbon-
substituted salicylates, to products thus prepared and to oil
compositions containing them.
From British patent specification 1,287,812 such products
and oil compostions containing them as detergents and wear
inhibitors are already known. It discloses the reaction of an
aliphatic hydrocarbon-substituted salicylic acid, or a metal salt
thereof, with elemental sulphur, an alkaline earth base, e.g. a
hydroxide, and a solvent, such as ethylene glycol, at at least
150C, and optionally further reaction with carbon dioxide. A
similar process is disclosed in British patent specification
1,194,503. A further process is given in UK patent specification
825,315 which describes the reaction of an alkyl phenol sulphide
with a metal alcoholate followed by carbon dioxide, to yield a
complex carbonated metal salt. Such products contain the carbon
dioxide in the form of carbonate or bicarbonate, and therefore
differ fro~l the alkyl salicylates whose preparation forms the
object of the present invention.
However, it has been found that this known process shows
the disadvantage of a substantial degree of decarboxylation
during the reaction of the salicylic acid, or a metal salt
thereof, with sulphur.
It has now been found that this problem can be avoided by
first sulphurizing an aliphatic hydrocarbon-substituted phenol
and then transforming the reaction product into a salicylic acid
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or metal salt thereof.
This invention therefore relates to a process for the
preparation of a sulphurized, C8-C30 alkyl-substituted metal
salicylate, characterized in that a C8-C30 alkyl phenol is sul-
phurized with a sulphur halide in an aliphatic hydrocarbon solvent,
or with elemental sulphur in the presence of a base catalyst and
a solvent chosen from an alkylene or polyalkylene glycol or a
lower alkylmonoether thereof at a temperature of from 100C to
250C, and the molar ratio of S:substituted phenol is 0.25 to
3 and the resulting product is transformed into an alkali metal
salicylate with an alkali metal hydroxide and carbon dioxide.
The product thus obtained is optionally transformed into an
overbased metal salicylate.
The invention furthermore relates tothe products thus
prepared and to oil compositions containing them.
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Suitable aliphatic hydrocarbon-substituted phenols are
described in the above-mentioned British patent specificiations.
Preferred are C8-C3-Oalkyl phenols-
These phenols may be sulphurized with sulphur halides,preferably sulphur chlorides such as SC12 and in particular S2C12.
Elemental sulphur can also be used.
The sulphurization with sulphur halide is carried out
in an aliphatic hydrocarbon solvent, e.g. n-hexane. The use of
aromatic solvents, such as xylene, should be avoided otherwise
these solvents may also be sulphurized with the sulphur halide.
The reaction can be carried out at ambient temperature,
although some heating may be applied, e.g. up to 60C.
The sulphurization with elemental sulphur can be carried
out by contacting the phenols with sulphur in the presence of
a solvent such as ethylene glycol and a base catalyst such as
lime (Ca(O~)2) at a temperature in the range of 100-250C, pre-
ferably 150-225C, whereby the final temperature should preferably
be at least 175C and more preferably at least 195C.
The above-mentioned solvent used in the sulphurization
step is an alkylene or polyalkylene glycol or a lower alkyl
monoether thereof, as disclosed in the above-mentioned British
patent specificiations 1,287,812 and 1,194,503. Most preferably
the solvent is ethylene glycol.
A promotor such as carboxylic acid or a metal salt
thereof, as described in British patent specification 1,194,503,
may also be present in the sulphurization step.
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The molar ratio of S:substituted phenol is e.g. 0.25
to 3, preferably 0.5 to 2.
The resulting product is acidified if necessary to
transform any phenate to phenol.
The transformation of the sulphurized phenols into a
salicylate is preferably carried out via the Kolbe synthesis by
reaction with sodium hydroxide and carbon dioxide as described
in the above-mentioned British patent specifications and in
British patent specificiation 786,167.
This sulphurized salicylic acid salt is a useful inter-
mediate for the preparation of the corresponding overbased
salicylates, which combine good detergency with reduced wear in
lubricating oil compositions. Suitable metals of the overbased
metal salicylate are e.g. alkali metals, such as Li,Cs, Na and
K, alkaline earth metals, such as Ca, Ba, Sr and ~g, and polyvalent
metals, such as Zn and Cr.
Alkaline earth metals, such as calcium, barium and mag-
nesium are preferred. Therefore the sulphurized alkali metal
salicylate is suitably transformed into the corresponding salicylic
acid, which is converted with a basic alkaline earth metal com-
pound, preferably the hydroxide, and carbon dioxide into an over-
based alkaline earth metal salicylate. The degree of overbasing
is expressed as the basicity index (BI) defined as the equivalent
ratio of metal: salicylic acid.
The overbasing of the sulphurized alkali metal salicylate
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may be carried out by acidification and reaction in a solvent,
such as a hydrocarbon solvent, preferably an aromatic hydrocarbon
solvent, such as xylene, with the basic metal compound and carbon
dioxide, as described in e.g. British patent specification 786,167.
To the resulting reaction mixture a light mineral oil
may be added and then the hydrocarbon s~olvent, and any water formed
may be removed by distillation.
The resulting oil solution of the sulphurized product
may be filtered, if aesired, and then be added to an oil, such
as a lubricating oil or a fuel oil, including gasoline.
Before or after sulphurization the product may be re-
acted with a boron compound, such as boric acid, as described
in the copending Canadian patent application 469,764.
The reaction products of this invention including mixtures
thereof can be incorporated in oil compositions, in particular
lubricating oil compositions or concentrates or fuels, e.g. auto-
mOtive crankcase oils, in concentrations within the range of 0.001
to 65, in particular 0.1 to 15~w based on the weight of
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the total compositions.
The lubricating oils to which the additives of the invention
can be added include not only mineral lubricating oils, but
synthetic oils also. Synthetic hydrocarbon-lubricating oils may
also be employed, as well as non-hydrocarbon synthetic oils
including dibasic acid esters such as di-2-ethyl hexyl sebacate,
carbonate esters, phosphate esters, halogenated hydrocarbons,
polysilicones, polyglycols, glycol esters such as C13 oxo acid
diesters of tetraethylene glycol, etc. Mixtures of these oils,
in particular of mineral lubricating oils, including hydrogenated
oils, and synthetic lubricating oils, can also be used.
When used in gasoline or fuel oil, e.g., diesel fuel, etc.,
then usually 0.001 to 0.5 %w, based on the weight of the total
composition of the reaction product will be used. Usually con-
centrates comprising e.g. 15 to 65 70w of said reaction product
in a hydrocarbon diluent and 85 to 35 %w mineral lubricating oil,
are prepared for ease of handling.
In the`above compositions other additives may also be pre-
sent, including dyes, pour point depressants, anti-wear, e.g.,
tricresyl phosphate, ~inc dithiophosphates, antioxidants such as
phenyl-alpha-naphthyl-amine~ bis-phenols such as 4,4'-methylene
bis (3,6-di-tert-butylphenol), viscosity index improvers, such as
hydrogenated (co)polymers of conjugated dienes and optionally
styrene, ethylene-higher olefin copolymers, polymethylacrylates,
polyisobutylene, and the li~e as well as ashless dispersants,
such as reaction products of polyisobutylene, maleic anhydride
and amines and/or polyols, or other metal-containing detergents,
such as overbased metal salicylates.
Reaction products of amines, formaldehyde and alkyl phenols
(Mannich bases) can also be present.
The invention is further illustrated by the following
Examples.
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Example 1
Preparation of sulphurized alkyl phenol.
A reaction vessel (5 litre) was charged with 2000 g tetra-
propenylphenol (7520 meq), 122 g calcium hydroxide (3300 meq), 364
g elemental sulphur (11375 meq) and 74 g ethylene glycol. Under
stirring this mixture was heated to 125 C and kept at that
temperature for one hour. The temperature was then raised to
150 ~C and kept at that temperature for one hour at a pressure
of about 550 mm Hg. Then the temperature was raised to 195 C
and kept at 50-60 mm Hg for two hours. The reaction product was
cooled, solvent was added and the mixture was filtered. The
solvent was removed leaving a dark, viscous product (yield:
2266 g; S: 8.2 %w) (Product A).
Example 2
Preparation of sulphuriæed alkyl phenol.
To a reaction vessel (2 litre) containing 524 g tetrapro-
penylphenol (2002 meq) and 520 g n-hexane a solution of 67.5 g
S2C12 (1000 meq of sulphur) in 70 g n-hexane was added dropwise
at such a rate that the temperature was kept constant at 20-40 C.
When the S2C12 addition was complete (2-3 hrs) the reaction
mixture was rinsed with nitrogen and the solvent removed under
reduced pressure (yield: 557 g; S: 5.0 %w) (Product B).
These Examples show that sulphurization with elemental
sulphur as well as with S2C12 is feasible.
Example 3
The product from example 2 was diluted with 500 g of xylene
and then heated to 135 C in a nitrogen atmosphere. An aqueous
solution of 100 g sodium hydroxide (25 % excess on OH intake) in
120 g water was added carefully (to prevent foaming) and water was
distilled off. The solution was carboxylated at 140 C and 14 bar
CO2 pressure. After acidification and water wash the yield was
587 g of sulphuriæed salicylic acids, acid number 1.98 meq/g and
sulphur content 4.72 %w (Product C).
5 3~37 2
Example _
A solution of 200 g of the sulphurized alkylsalicylates of
example 3 (396 meq) in 200 g of xylene and 120 g of methanol was
treated with 59 g of Ca(OH)2 (1595 meq) for lh at 55 C. The
reaction product was filtered and the solvents were evapora~ed
under reduced pressure resulting in a product (223 g) with 6.8 %w
Ca, 3.9 %w S and a B.I. of 1.5 (Product D).
Example 5
A solution of 200 g of the sulphurized alkylsalicylates of
example 3 (396 meq) in 200 g of xylene and 120 g of methanol was
treated with 59 g of Ca(OH)2 (1595 meq) for lh at 55C. Subse-
quently 13.9 g of C02 (632 meq) was introduced. Workingup yielded
253.5 g of a product with 11.5%w Ca, 3.7 %w S and a B.I. of 3.0
(Product E).170 g of product E was mixed with 155 g of mineral
lubricating oil, resulting in an oil concentrate with 6.0 %w Ca,
1.9 %w S and a B.I. of 3.0 (product F).
Comperative Experiment
To 97.6 g (205 meq) of neat C14 18 alkyl salicylic acids were
added 37.9 (1025 meq) of Ca(OH)2 and 69.5 g of a mineral lubri-
cating oil, resulting in a 1.0 meq/g mixture of acids. 133.2 g of
this mixture (133.2 meq), 4.26 g of S (133.2 meq) and 1.0 g of
ethylene glycol were heated under stirring to 125 C and kept at
that temperature for one hour. The temperature was further raised
to 150 C (1 hour, pressure: 550 mm Hg) and 195 C (2 hours, 50-60
mm Hg). The reaction mixture was cooled, diluted with n-hexane,
filtered through filter aid and finally evaporated to yield a very
viscous, dark material. Yield: 112.3 g, S: 1.6 %w.
It appeared that during the sulphurization 20% decarboxy-
lation occurred (acid number of starting material 1.22 meq/g and
of product 0.95 meq/g, determined after acidification with HCl
extraction with diethyl ether, phase separation and evaporation of
the solvent).
TESTS
In two CRC L38 tests (ASTM STP 509 A, part IV) the performance of
product F (see Example 5) was compared with that of unsulphurized
overbased Ca C14 18-alkyl salicylate. Thereto two for~ulations
were prepared, formulation I comprising a 15W40 mineral
lubricating oil containing commercial dispersant, detergent and
anti-oxidant additives and 0.14 %w (as Ca) of overbased Ca
C14 18-alkyl salicylate (B.I. = 3), and formulation II comprising
the same 15W40 lubricating oil and 0.14 ~Ow (as Ca) of product F.
The results of the CRC L38 tests, in which the bearing weight loss
is determined, are shown in Table I.
TABLE I
Formulation I II
Bearing weight loss, mg 45.4 29.6
" " " " 45.7 36.7
. ' ' ' ``
It appears that use of the sulphurized product of the
invention results in a reduction of the bearing weight loss.
