PROCESS FOR PREPARING2-HYDRO YPHENYL
ALKENYL BENZOTRIAZOLE COMPOUNDS AND PROCESS FOR PREPARING SILOXANE COMPOUNDS CONTAINING
2-HYDROXYPHENYL BENZOTRIZOLE FUNCTION
5 The present invention relates to a process for preparing a 2-hydroxyphenyl
alkenyl benzotriazole compound in particular of formula (1) that will be defined
in detail later.
The present invention relates to a process for preparing siloxane compounds
10 containing a 2-hydroxyphenylbenzotriazole function in particular of formula (3)
that will be defined in detail later, comprising a) the preparation of a 2-
hydroxyphenyl alkenyl benzotriazole compound obtained according to the
preceding preparation process, and b) the hydrosilylation reaction with the said
2-hydroxyphenyl alkenyl benzotriazole compound with a siloxane containing an
i s SiH function, in the presence of a suitable catalyst and a suitable solvent.
It is known that light radiation with wavelengths of between 280 n and 400 nm
allows browning of the human epidermis, and that rays with wavelengths more
particularly of between 280 and 320 nm, which are known as UV-B rays, may
20 harm the development of a natural tan. For these reasons, and also for
aesthetic reasons, there is constant demand for means for controlling this
natural tanning in order thus to control the colour of the skin; this UV-B radiation
should thus be screened out.
5 It is also known that UV-A rays, with wavelengths of between 320 and 400 nm,
which cause browning of the skin, are liable to induce impairment thereof,
especially in the case of sensitive skin or of skin that is continually exposed to
sunlight. UV-A rays in particular cause loss of elasticity of the skin and the
appearance of wrinkles, leading to premature ageing of the skin. Thus, for
0 aesthetic and cosmetic reasons, for instance maintenance of the natural
elasticity of the skin, more and more people wish to control the effect of UV-A
rays on their skin. It is thus desirable also to screen out UV-A radiation.
For the purpose of protecting the skin and keratin materials against UV radiation,
5 antisun compositions comprising organic or inorganic screening agents that are
active in the UV-A range and active in the UV-B range are generally used.
Many sectors of non-cosmetic industry also resort to the use of UV-screening
agents for photoprotecting various materials against the effects of UV radiation
0 and in particular sunlight.
This is especially the case for paint, ink or protective covering formulations
intended to be applied onto products that are permanently exposed to UV
radiation such as building materials, the materials used in the motor vehicle
5 industry, and packaging plastics. UV-screening agents that are transparent,
photostable, compatible with the usual ingredients contained in the said
formulations and effective in the light-fastness of the desired colour are most
particularly sought for these colouring formulations.
This is also the case for the polymer compositions used especially in the
manufacture of plastics that are stable on storage, in which UV-screening
agents are sought that are particularly suited to processes for manufacturing
and transforming polymers that especially need to have good resistance to high
temperatures for extrusion.
In the industry of textiles made from natural fibres, artificial fibres or synthetic
fibres, broad-spectrum photostable UV-screening agents are sought that are
compatible with the processes for manufacturing the said fibres, especially in
the context of manufacturing polyamide fibres such as nylon, which are resistant
to strong heat and which allow incorporation of UV protection during extrusion.
UV-screening agents that show good affinity for and good adhesion to the fibres,
thus affording them in particular good resistance to successive washing, are
also sought. The desired UV-screening agents should also allow good
protection not only of textile fibres but also of the skin and of the other human
keratin materials in contact with the said fibres.
Similar problems also arise in the manufacture of paper generally made of
cellulose fibres, in which the UV-screening agents used must also be
photostable, transparent and compatible with the other usual ingredients and
adapted to the various papermaking techniques.
The industry of mineral or organic glasses and especially of those used in
ophthalmology is in search of UV-screening agents that must have a broad
spectrum of action (active in the UV-A range and in the UV-B range), which are
photostable, transparent and compatible with the various techniques for treating
glasses, for instance the process for attaching glass to the matrix or the
application of a photoprotective covering, for example in the case of
polycarbonate glasses.
One particularly interesting family of organic screening agents with absorbent
properties both in the UV-A range and in the UV-B range is that of siloxane
compounds containing a 2-hydroxyphenylbenzotriazole function.
The term "siloxane compound containing a 2-hydroxybenzotriazole function"
means any molecule comprising in its structure at least one -SiO group and at
least one 2-hydroxyphenylbenzotriazole group; the said molecule possibly being
in the form of a simple siloxane or alkoxysilane compound, an oligosiloxane or a
polysiloxane.
In particular, siloxane compounds containing a 2-hydroxyphenylbenzotriazole
function of formula (4) below:
(A)— (D) (4)
in which group (A) represents the silicone part of formula (4) with:
- R, which may be identical or different, denote a linear or branched and
optionally halogenated or unsaturated C1-C30 alkyl radical, a C6-C 2 aryl radical,
a linear or branched C o alkoxy radical or a group -OSi(CH3)3;
- a is an integer between 0 and 2 inclusive;
and in which group (D) represents the group of formula (1a) with:
- n is an integer between 0 and 3 inclusive;
- T, which may be identical or different, are chosen from linear or branched
Ci-C 8 alkyl radicals, halogens, preferably chlorine, and linear or branched C1-C4
alkoxy radicals;
- represents hydrogen or a methyl radical,
are known.
In addition to the units of formula (A), the organosiloxane may comprise units of
formula:
in which,
- R has the same meaning as in formula (3);
- b = 1, 2 or 3.
Preferably, the compounds of formula (4) are represented by formulae (3a)
(3b) below:
(3a)
in which:
- (D) corresponds to formula (1a) as defined above,
- R2, which may be identical or different, are chosen from linear or branched
C1-C20 alkyl, phenyl, 3,3,3-trifluoropropyl and trimethylsilyloxy radicals or the
hydroxyl radical,
- (B), which may be identical or different, are chosen from the radicals R2 and
the group (D),
r is an integer between 0 and 200 inclusive,
- s is an integer ranging from 0 to 50 and if s = 0, at least one of the two symbols
(B) denotes (D),
- u is an integer ranging from 1 to 10,
- t is an integer ranging from 0 to 10, it being understood that t + u is greater
than or equal to 3.
The linear or cyclic diorganosiloxanes of formula (3a) or (3b) are random
oligomers or polymers in which R2 is preferably a methyl radical.
The linear diorganosiloxanes of formula (3a) are particularly preferred.
As examples of compounds of formula (3) that are particularly preferred,
mention will be made of the compounds of formulae (a) to (h) below:
(h) random derivative r = s = 5
(a) = 2-(5-methoxy-2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-(2-methyl-3-{1 ,3,3,3-
tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl}propyl)phenol
(b) 2-(2H-1 ,2,3-benzotriazol-2-yl)-6-methoxy-4-(3-{1 ,3,3,3-tetramethyl-1-
[(trimethylsilyl)oxy]disiloxanyl}propyl)phenol
(c) = 2-(2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-(2-methyl-3-{1 ,3,3,3-tetramethyl-
1-[(trimethylsilyl)oxy]disiloxanyl}propyl)phenol
(d) = 2-(2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-(3-{1 ,3,3,3-tetramethyl-1-
[(trimethylsilyl)oxy]disiloxanyl}propyl)phenol
(e) = 2-(2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-[3-
(undecamethylpentasiloxanyl)propyl]phenol
(f) = 2-(2H-1 ,2,3-benzotriazol-2-yl)-6-[3-(1 1-{3-[3-(2H-1 ,2,3-benzotriazol-2-yl)-2-
hydroxy-5-methylphenyl]propyl}-1 , ,3,3,5,5,7,7,9,9, 11,1 1-
dodecamethylhexasiloxanyl)propyl]-4-methylphenol
(g) 2-(2H-1 ,2,3-benzotriazol-2-yl)-6-[3-(1 1-{3-[3-(2H-1 ,2,3-benzotriazol-2-yl)-2-
hydroxy-5-(1 ,1,3,3-tetramethylbutyl)phenyl]propyl}-1 ,1,3,3,5,5,7,7,9,9, 11, 1 1-
dodecamethylhexasiloxanyl)propyl]-4-(1 ,1,3,3-tetramethylbutyl)phenol
.Even more particularly preferred are the derivatives of formula (3a) in which
r = 0 , s = 1, and and (B) are methyl.
Even more preferably, the compound Drometrizole Trisiloxane (CTFA name) is
known, corresponding to the following formula:
(c)
product manufactured by the company Rhodia under the trade name Silatrizole.
These compounds and their syntheses have been described in patents
US 4 316 033, US 4 373 060, EP 0 388 218, US 5 089 250, EP 0 354 145,
EP 0 708 108, EP 0 7 11 779 and patent application WO 94/06404.
The siloxane compounds containing a 2-hydroxyphenylbenzotriazole function
and especially those of formula (4) are obtained, according to these documents,
by hydrosilylation reaction of a 2-hydroxyphenyl alkenyl benzotriazole
compound (especially that of formula (1) defined below) with a siloxane
containing an SiH function (especially of formula (2) defined below) in the
presence of a suitable catalyst and a suitable solvent (in particular toluene) and
according to the reaction scheme A below:
SCHEME A
(4)
In formula (1), T, n and R have the same meaning as in the preceding
formula (1a), and in formula (2), R and a have the same meaning as in the
preceding formula (3).
As emerges from formula (1a) given above, the attachment of the chain unit:
to the 2-hydroxyphenylbenzotriazole unit, which thus ensures attachment of the
said 2-hydroxyphenylbenzotriazole unit to the silicon atom of the silicone chain,
takes place exclusively in position 3 (aromatic nucleus bearing the hydroxyl
function) or in position 5 (when position 3 contains a radical T).
Similarly, the attachment of the substituent unit T may take place in all the other
positions available on the 2-hydroxyphenylbenzotriazole. However, preferably,
this attachment takes place in position 3, 4 , 4', 5 and/or 6.
The 2-hydroxyphenyl alkenyl benzotriazole compounds, starting products in the
synthesis of the siloxane screening agents containing a 2-
hydroxyphenylbenzotriazole function, are known per se and their syntheses
have been described in patents FR 1 325 404, US 4 316 033, US 4 328 346, US
4 373 060, GB 2 077 280, EP 0 392 883, EP 0 708 108, EP 0 7 11 779 and US
2009/0 270 632.
In patent FR 1 325 404, the 2-hydroxyphenyl alkenyl benzotriazole compounds
are obtained via a Claisen rearrangement on a 2-O-alkenylphenylbenzotriazole
compound, according to the following operating conditions: without solvent, or
alternatively with dimethylaniline or specific polymers as solvents (commercial
polyethylene glycol terephthalate), at 180-220 C and recrystallization in alcohol.
The overall yields for this process are unsatisfactory.
In patents US 4 316 033, US 4 373 060 and GB 2 077 280, the 2-hydroxyphenyl
alkenyl benzotriazole compounds are obtained via a synthetic process
comprising two chemical steps. In a first stage, alkylation of a 2-hydroxy-5-
alkylphenylbenzotriazole compound is performed with an alkenyl halide in the
presence of a base (for example potassium carbonate or sodium methoxide)
and with, as solvent: acetone, diethyl ketone or 2-butanone. The product
resulting from this alkylation is heated at 200°C under a nitrogen atmosphere for
1 hour 30 minutes to give, after recrystallization from a methanol/chloroform
mixture, the corresponding 2-hydroxyphenyl alkenyl benzotriazole derivative.
The overall yield for the two steps (44%) of this process is unsatisfactory.
In patent EP 0 392 883, the 2-hydroxyphenyl alkenyl benzotriazole derivatives
are also obtained via a synthetic process in two chemical steps. In the first step,
an alkenyl halide is reacted with a 2-hydroxyphenyl-5-alkylbenzotriazole
compound in the presence of a base (an alkali metal or alkaline-earth metal
hydroxide or carbonate, or an alkali metal amide, alkoxide or hydride) in a
solvent such as water or an organic solvent such as an alcohol, dioxane,
dimethyl sulfoxide or dimethylformamide, at a temperature between room
temperature and the boiling point of the solvent. The Claisen rearrangement is
performed on the product resulting from the first step by heating to at least
170°C approximately, optionally in the presence of a solvent. The overall yield
for the two steps of this process is not entirely satisfactory.
In patent application US 2009/0 270 632, the 2-hydroxyalkenylphenylbenzotriazole
compounds are also obtained via a synthetic process comprising
the following steps:
(a) a 2-hydroxy-5-alkylphenylbenzotriazole compound, a base (sodium
carbonate, potassium carbonate, sodium hydrogen carbonate, potassium
hydrogen carbonate, triethylamine or tricaprylylamine) and molecular sieves
(3 A and 5 A calcium aluminium silicate) in a first solvent (N,N-dialkylaniline
containing from 1 to 3 carbon atoms) and 3-chloro-2-alkylpropylene dissolved in
a second solvent (an alkyl ketone containing from 1 to 5 carbon atoms) are
mixed together; the ratio of benzotriazole derivative to base being between 1/0.1
and 1/1 ;
(b) the various solutions are mixed together in the reactor;
(c) the reactor is made inert with nitrogen;
(d) the reaction medium is heated to a reaction temperature of between 70°C
and 190°C;
(e) the resulting mixture is filtered;
(f) the product is recrystallized (from halogenated solvents, ,-dimethylformamide,
non-aromatic alcohol or halobenzene). Although the overall yields
for the given examples are between 72% and 86%, there is still a need to
improve this yield. Furthermore, the solvents N,N-dimethylformamide,
,-dialkylaniline and the amines triethylamine and tricaprylylamine used in this
process are products that are known for their toxic effects and their
environmental unfriendliness.
There is still a need to find a process for preparing a 2-hydroxyphenyl alkenyl
benzotriazole compound with a better overall yield, without the drawbacks
encountered in the prior art processes.
The Applicant has discovered, surprisingly, that this objective can be achieved
with a process for preparing a 2-hydroxyphenyl alkenyl benzotriazole compound,
characterized in that it comprises at least the following two chemical steps:
1) an etherification is performed on a 2-hydroxyphenylbenzotriazole compound
in water and/or at least one suitable organic solvent by reacting an alkenyl
halide in the presence of at least one phase-transfer agent and of at least one
base so as to obtain the corresponding 2-O-alkenylphenylbenzotriazole
compound;
2) a Claisen rearrangement is performed on the 2-O-alkenylphenylbenzotriazole
compound thus obtained, by heating the reaction mixture to a temperature
above 170°C with at least one suitable organic solvent.
This process may be represented by Scheme B below:
SCHEME B
Ether formation
Such a process thus makes it possible to achieve overall yields of greater than
80% and purity levels of greater than 99% without the drawbacks mentioned
previously. Furthermore, this process has the advantage of being able to be
performed in a single reactor (one-pot).
This discovery forms the basis of the present invention.
The present invention thus relates to a process for preparing a 2-hydroxyphenyl
alkenyl benzotriazole compound, characterized in that it comprises at least the
following two chemical steps:
1) an etherification is performed on a 2-hydroxyphenylbenzotriazole compound
in water and/or at least one suitable organic solvent by reacting an alkenyl
halide in the presence of at least one phase-transfer agent and of at least one
base so as to obtain the corresponding 2-O-alkenylphenylbenzotriazole
compound of formula (7);
2) a Claisen rearrangement is performed on the 2-O-alkenylphenylbenzotriazole
compound thus obtained, by heating the reaction mixture to a temperature
above 170°C with at least one suitable organic solvent.
The first chemical step of the process according to the invention is a standard
etherification between an alkenyl halide of formula (6) and a 2-hydroxyphenylbenzotriazole
derivative of formula (5).
The second chemical step of the process according to the invention involves a
Claisen rearrangement in which the alkenyl ether group migrates from the
oxygen to the carbon ortho (or para) to the hydroxyl group under the conditions
described by Tarbell (Organic Reactions, Vol. 2 , John Wiley, New York, 1944,
page 1) by heating the compound of formula (7) to at least 170°C approximately.
For the etherification step, the temperatures of the reaction mixture are
preferably between 20°C and 150°C and more particularly between 60°C and
90°C.
For the Claisen rearrangement step, the temperatures of the reaction mixture
are preferably between 170°C and 250°C and more particularly between 200°C
and 220°C.
More particularly, the process in accordance with the invention comprises the
following steps:
i) an etherification is performed on a 2-hydroxyphenylbenzotriazole compound in
water and/or at least one suitable organic solvent, by reacting an alkenyl halide
in the presence of at least one phase-transfer agent and of at least one base so
as to obtain the corresponding 2-O-alkenylphenylbenzotriazole compound of
formula (7);
ii) the reaction mixture is cooled to room temperature and the reaction medium
is preferably diluted with water and/or the said suitable organic solvent(s);
iii) total removal of the water from the reaction medium is performed;
iv) a Claisen rearrangement is performed on the 2-O-alkenylphenylbenzotriazole
compound obtained in step i) by heating the reaction mixture to a temperature of
greater than 170°C in the presence of at least one suitable organic solvent;
v) the solvent(s) are eliminated;
vi) recrystallization is performed in the presence of at least one recrystallization
solvent.
Preferentially, the process of the invention will be performed in a single reactor.
The present invention more particularly relates to a process for preparing a
2-hydroxyalkenylphenylbenzotriazole compound of formula (1) below:
(1)
in which
- n is an integer between 0 and 3 inclusive;
- T, which may be identical or different, are chosen from linear or branched
Ci-Ce alkyl radicals, halogens and linear or branched C1-C4 alkoxy radicals;
- R represents hydrogen or a methyl radical,
characterized in that it comprises at least the following two chemical steps:
1) an etherification is performed on a compound of formula (5) below:
in which the radicals T and n have the same meanings indicated in formula (1)
in water and/or at least one suitable organic solvent by reacting, in the presence
of at least one phase-transfer agent and of at least one base, an alkenyl halide
of formula (6) below:
in which X denotes a halogen atom, preferably bromine or chlorine, and R
denotes hydrogen or methyl, the said halide preferably being introduced by
addition to the reaction medium;
2) a Claisen rearrangement is performed on the compound thus obtained of
formula (7) below:
in which T, n and R have the same meanings indicated in formula (1), by
heating the reaction mixture to a temperature of greater than 170°C in the
presence of at least one suitable organic solvent.
According to one preferential form, the organic solvent(s) that may be used in
the etherification step, optionally in step ii) of cooling the reaction medium and in
the Claisen rearrangement step, are water-immiscible and have a boiling point
of greater than 200°C, preferably between 200 and 270°C and more
preferentially between 200 and 220°C.
The term "water-immiscible solvent" means any solvent that forms with water a
heterogeneous mixture with two separate phases.
Among the water-immiscible organic solvents with a boiling point of greater than
200°C, mention may be made of: benzyl alcohol (boiling point: 205°C),
diethylene glycol monobutyl ether (boiling point: 224-228°C), diphenyl ether
(boiling point: 258°C), tetralin (boiling point: 206-208°C), methylnaphthalene
(boiling point: 244°C) and the biphenyl/diphenyl ether mixture (boiling point:
257°C). Benzyl alcohol will be more particularly preferred.
Among the 2-hydroxyphenylbenzotriazole derivatives of formula (5) that may be
used as starting material in the process of the invention, mention may be made
of the following compounds: 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-
hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)-5-
chlorobenzotriazole. 2-(2-Hydroxy-5-methylphenyl)benzotriazole will be
preferred.
Among the alkenyl halides that may be used in the process of the invention,
mention may be made of the following compounds: 1-chloro-2-propene (allyl
chloride), 1-bromo-2-propene (allyl bromide), 1-chloro-2-methyl-2-propene
(methallyl chloride) and 1-bromo-2-methyl-2-propene (methallyl bromide), in a
ratio that may preferably range from 1.05 to 1.7 equivalents relative to the
starting 2-hydroxyphenylbenzotriazole.
Methallyl chloride will be preferred. The preferential ratio will be between 1.3
and 1.5 equivalents relative to the starting 2-hydroxyphenylbenzotriazole
compound.
The concentration of the starting 2-hydroxyphenylbenzotriazole derivative in the
reaction medium of the etherification step preferably ranges from 5% to 80% by
weight and preferentially from 20% to 50% by weight relative to the total weight
of the reaction medium of the etherification step.
Among the phase-transfer agents that may be used in the process of the
invention, mention may be made of the following compounds:
tetrabutylammonium halides, tetrabutylammonium hydrogenosulfate,
benzyltrimethylammonium chloride and preformed catalysts between
tributylamine and the alkenyl halides. They will preferably be present in a ratio
ranging from 3 mol% to 15 mol% relative to the starting
2-hydroxyphenylbenzotriazole derivative.
Tetrabutylammonium bromide and the preformed catalyst between tributylamine
and methallyl chloride will be preferred. They will be used in a preferential ratio
of between 3 mol% and 6 mol% relative to the starting 2-hydroxyphenyl¬
benzotriazole.
Among the base that may be used in the process of the invention, mention may
be made of the following compounds: alkali metal bases such as sodium
bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate,
sodium hydroxide and potassium hydroxide. It is preferably used in a ratio
ranging preferably from 0.7 to 1.5 equivalents relative to the starting
2-hydroxyphenylbenzotriazole of formula (5). Potassium bicarbonate will be
preferred, in a preferential ratio of from 1.0 to 1.2 equivalents relative to the
starting 2-hydroxyphenylbenzotriazole.
Among the recrystallization solvents, mention may be made of isopropanol,
methanol, ethanol and benzyl alcohol, or mixtures thereof. Isopropyl alcohol will
be preferred.
Another subject of the invention thus relates to a process for preparing a
siloxane compound containing a benzotriazole function, characterized in that it
comprises at least the following steps:
a) a 2-hydroxy phenyl alkenyl benzotriazole compound is prepared according to
the process defined previously;
b) a hydrosilylation reaction is performed on the said 2-hydroxyphenyl alkenyl
benzotriazole compound in the presence of a catalyst and of a suitable solvent
with a siloxane containing an SiH function.
More particularly, the invention relates to a process for preparing a siloxane
compound containing a benzotriazole function of formula (4) below:
(A)— (D) (4)
(A) = (S )-°(3-a)/2 (3)
in which group (A) represents the silicone part of formula (3) with:
- R, which may be identical or different, denote a linear or branched and
optionally halogenated or unsaturated Ci-C 30 alkyl radical, a C6-Ci2 aryl radical,
a linear or branched C1-C10 alkoxy radical or a group -OSi(CH3)3;
- a is an integer between 0 and 2 inclusive;
and in which group (D) represents a group of formula (1a) with:
- n is an integer between 0 and 3 inclusive;
- T, which may be identical or different, are chosen from linear or branched
Ci-Cs alkyl radicals, halogens and linear or branched C1-C4 alkoxy radicals;
- R represents hydrogen or a methyl radical.
In addition to the units of formula (A), the organosiloxane may comprise
formula:
in which,
- R has the same meaning as in formula (3);
- b = 1, 2 or 3.
characterized in that it comprises at least the following steps:
a) a 2-hydroxyphenyl alkenyl benzotriazole compound of formula (1) below is
prepared:
(1)
in which R , T and n have the same meaning as in formula (1a), according to
the process as defined previously;
b) a hydrosilylation reaction is performed on the said 2-hydroxyphenyl alkenyl
benzotriazole compound of formula (1) with a siloxane containing an SiH
function of formula (2) below:
H (Si)-0 (3.a)/2
(2)
R
in which R and a have the same meaning as in formula (3), in the presence of a
suitable catalyst and a suitable solvent.
Among 2-hydroxyphenyl benzotriazole derivatives of formula (1) that can be
used as starting product in the process of the invention, mention may be made
of the following derivatives of formulae (i) to (m):
(m)
(i) = 6-allyl-2-(2H-1 ,2,3-benzotriazol-2-yl)-4-methylphenol
G) = 2-(2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-(2-methylprop-2-enyl)phenol;
(k) = 2-(5-methoxy-2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-(2-methylprop-2-
enyl)phenol
(I) = 6-allyl-2-(2H-1 ,2,3-benzotriazol-2-yl)-4-(t-octyl)phenol
(m) = 2-(5-chloro-2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-(6-allyl)phenol
Even more preferably, use will be made of the compound 2-(2H-1 ,2,3-
benzotriazol-2-yl)-4-methyl-6-(2-methylprop-2-enyl)phenol of formula (j) below:
The siloxane of formula (2) that may be used according to the invention is
preferentially chosen from 1,1,1 ,3,5,5,5-heptamethyltrisiloxane,
diethoxy(methyl)silane and 1, 1 , 1 ,5,5,5-hexamethyl-3-[(trimethylsilyl)oxy]trisiloxane.
1,1 , 1 ,3,5,5,5-Heptamethyltrisiloxane will be preferred.
The concentration of the siloxane of formula (2) in the reaction medium
containing the 2-hydroxyalkenylphenylbenzotriazole compound of formula (1)
may range between 30% and 90% and preferentially from 40% to 70%.
The siloxane of formula (2) used is placed in a ratio of 1.0 to 1.5 equivalents
relative to the 2-hydroxyphenylbenzotriazole derivative of formula (1), and more
preferentially from 1.0 to 1.1 equivalents.
The catalysts used to perform the hydrosilylation reaction on the
2-hydroxyalkenylbenzotriazole compounds with the siloxanes containing an SiH
function are fully described in the literature; mention may be made in particular of
the complexes of platinum and of an organic product described in patents
US 3 159 601 , US 3 159 602, US 3 220 972, EP 0 057 459, EP 10 188 978 and
EP 0 190 530 and the complexes of platinum and of vinyl organopolysiloxanes
described in patents US 3 419 593, US 3 377 432, US 3 715 334 and US 3 814 730
(Karstedt catalyst).
The solvent used for the hydrosilylation is preferably toluene.
More particularly, the aring the compound
Drometrizole Trisiloxa ula:
(c)
comprising at least the following steps:
a) the compound 2-(2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-(2-methylprop-2-
enyl)phenol is prepared according to the process as defined previously;
b) a hydrosilylation reaction is performed on the said compound with the
siloxane containing an SiH function: 1,1 , 1 ,3,5,5,5-heptamethyltrisiloxane in the
presence of a suitable catalyst and a suitable solvent.
Concrete but in no way limiting examples illustrating the invention will now be
given.
EXAMPLE 1: Preparation of 2-(2H-1 .2,3-benzotriazol-2-yl)-4-methyl-6-(2-
methylprop-2-enyl)phenol in a water/benzyl alcohol two-phase mixture:
2-(2-Hydroxy-5-methylphenyl)benzotriazole (2 g ; 8.9 mmol) is charged under
nitrogen into a reactor with potassium carbonate ( 1 .83 g; 13.1 mmol),
tetrabutylammonium bromide (143.1 mg; 0.44 mmol) and 10 ml of a
water/benzyl alcohol mixture (4/1). The medium is heated to 80-85°C and
methallyl chloride ( 1.212 g ; 13.4 mmol) is added dropwise. After addition, the
medium is heated at 80-85°C. After 17 hours, the medium is cooled and the
phases are allowed to separate by settling. The organic phase is washed with
water (twice 2 ml). The water is removed by distillation and the benzyl alcohol
solution is used directly in reaction at 200°C. After reaction, the solvent is
evaporated off and the crude product is taken up at 80°C in 4.5 ml of
isopropanol. The medium is then cooled to a temperature of between 0 and
10°C. The solid is filtered off and washed with cold isopropanol. After drying
under vacuum, 2 g of white crystals are obtained (81% yield and 99.5% purity).
EXAMPLE 2: Preparation of 2-(2H-1,2,3-benzotriazol-2-yl)-4-methyl-6-(2-
methylprop-2-enyl)phenol in benzyl alcohol alone:
2-(2-Hydroxy-5-methylphenyl)benzotriazole (2 g; 8.9 mmol) is charged under
nitrogen into a reactor with potassium carbonate ( 1.83 g; 13.1 mmol),
tetrabutylammonium bromide ( 1 14.5 mg; 0.35 mmol) and 8 ml of benzyl alcohol.
The medium is heated to 80-85°C and methallyl chloride ( 1.212 g; 13.4 mmol) is
added dropwise. After addition, the medium is maintained at 80-85°C. After
18 hours, the medium is cooled and diluted with 2 ml of water. The aqueous
phase is separated out and the organic phase is washed with water (twice 1 ml).
The water is removed by distillation and the benzyl alcohol solution is used
directly in reaction at 200°C. After reaction, the solvent is evaporated off and the
crude product is taken up at 80°C in 4.5 ml of isopropanol. The medium is then
cooled to a temperature of between 0 and 10°C. The solid is filtered off and
washed with cold isopropanol. After drying under vacuum, 2.1 g of white crystals
are obtained (83% yield and 99.5% purity).
EXAMPLE 3: Preparation of 2-(2H-1,2,3-benzotriazol-2-yl)-4-methyl-6-(2-
methylprop-2-enyl)phenol in benzyl alcohol alone:
2-(2-Hydroxy-5-methylphenyl)benzotriazole (45 g; 0.1997 mol) is charged under
nitrogen into a reactor with potassium carbonate (30.33 g; 0.2171 mol) and
45 ml of benzyl alcohol. The medium is heated to 80-85°C. A solution of catalyst
prepared beforehand by mixing with stirring tributylamine (9.25 g; 49.9 mmol)
and methallyl chloride (36.16 g; 0.3994 mol) is poured into the medium. After
addition, the medium is heated at 80-85°C for 19 hours. After reaction, the
medium is cooled and diluted with water (45 ml). The organic phase is washed
with water (twice 45 ml). After separation of the phases by settling, the medium
is concentrated under vacuum to remove the water. The medium is rediluted
with 15 ml of benzyl alcohol and is then heated to 200-206°C. After reaction, the
medium is cooled and concentrated under vacuum. 103 ml of isopropanol are
then added at 80°C. The medium is then cooled to a temperature of between 0
and 10°C. The solid is filtered off and washed with isopropanol. After drying
under vacuum, 46.3 g of white crystals are obtained (83% yield and 99.5%
purity).
EXAMPLE 4 : Preparation of 2-(2H-1.2,3-benzotriazol-2-ylM-methyl-6-(2-
methylprop-2-enyl)phenol in a tetralin/water two-phase mixture:
2-(2-Hydroxy-5-methylphenyl)benzotriazole (15 g; 65.6 mmol) is charged under
nitrogen into a reactor with potassium carbonate (10.1 1 g; 72.4 mmol),
tetrabutylammonium chloride (0.91 g ; 3.28 mmol) and 45 ml of a water/tetralin
mixture (2/1). The medium is heated to 80-85°C and methallyl chloride (10.25 g ;
0.1 12 mol) is added dropwise. After addition, the medium is heated at 80-85°C.
After 26 hours, the medium is cooled and the phases are separated by settling.
The organic phase is washed with 35 ml of water. After separation of the phases
by settling, the medium is concentrated under vacuum to remove the water. The
medium is rediluted with 12 ml of tetralin and is then heated at 200-206°C. The
medium is cooled and concentrated under vacuum. 30 ml of isopropanol are
then added at 80°C. The medium is then cooled to a temperature of between 0
and 10°C. The solid is filtered off and washed with isopropanol. After drying
under vacuum, 15.8 g of white crystals are obtained (85% yield and 99.7%
purity).
EXAMPLE 5 : Preparation of 2-(2H-1.2,3-benzotriazol-2-ylM-methyl-6-(2-
methylprop-2-enyl)phenol in water and diphenyl ether:
2-(2-Hydroxy-5-methylphenyl)benzotriazole (45 g; 0.1997 mol), potassium
carbonate (30.40 g; 0.22 mol), tributylammonium chloride (2.77 g; 10 mmol) and
90 ml of water are introduced into a reactor under nitrogen. The medium is
heated to 80~85°C. Next, methallyl chloride (23.79 g; 0.26 mol) is added
dropwise. After addition, the medium is maintained at 80-85°C until conversion
is complete. After reaction, the medium is cooled and diluted with a diphenyl
ether/water mixture (1/1) (90 ml). The phases of the medium are separated by
settling and the organic phase is washed with water (100 ml). The aqueous
phase is separated out and the organic phase is placed under vacuum to
remove the water. The medium is rediluted in 20 ml of solvent and is heated to
200~206°C. After reaction, the medium is cooled and the solvent is removed by
distillation. 104 g of isopropanol are then added at 80°C and the medium is then
cooled to between 0 and 10°C. The precipitate is filtered off and washed with
isopropanol (twice 11.3 ml). The product is dried under vacuum and 5 1.2 g
(92.5% yield) of white crystals are obtained in a purity of 99.8%.
CLAIMS
1. Process for preparing a 2-hydroxyphenyl alkenyl benzotriazole
compound, characterized in that it comprises at least the following two chemical
steps:
1) an etherification is performed on a 2-hydroxyphenylbenzotriazole compound
in water and/or at least one organic solvent with a boiling point of greater than
200°C by reacting an alkenyl halide in the presence of at least one phasetransfer
agent and of at least one base so as to obtain the corresponding 2-0-
alkenylphenylbenzotriazole compound;
2) a Claisen rearrangement is performed on the 2-O-alkenylphenylbenzotriazole
compound thus obtained, by heating the reaction mixture to a temperature
above 170°C with at least one organic solvent with a boiling point of greater
than 200°C.
2. Process according to Claim 1, comprising the following steps:
i) an etherification is performed on a 2-hydroxyphenylbenzotriazole compound in
water and/or at least one organic solvent with a boiling point of greater than
200°C, by reacting an alkenyl halide in the presence of at least one phasetransfer
agent and of at least one base so as to obtain the corresponding
2-O-alkenylphenylbenzotriazole compound;
ii) the reaction mixture is cooled to room temperature and the reaction medium
is preferably diluted with water and/or the said organic solvent with a boiling
point of greater than 200°C;
iii) total removal of the water from the reaction medium is performed;
iv) a Claisen rearrangement is performed on the 2-O-alkenylphenylbenzotriazole
compound obtained in step i) by heating the reaction mixture to a temperature of
greater than 170°C in the presence of at least one organic solvent with a boiling
point of greater than 200°C;
v) the solvent(s) are eliminated;
vi) recrystallization is performed in the presence of at least one recrystallization
solvent.
3. Process according to Claim 1 or 2 , characterized in that it is performed in a
single reactor.
4. Preparation process according to any one of Claims 1 to 3 , characterized in
that a 2-hydroxyphenyl alkenyl benzotriazole compound of formula (1) below is
prepared:
( 1)
in which
- n is an integer between 0 and 3 inclusive;
- T, which may be identical or different, are chosen from linear or branched
Ci-Ce alkyl radicals, halogens, preferably bromine or chlorine, and linear or
branched C1-C4 alkoxy radicals;
- R represents hydrogen or a methyl radical,
and in that the said process comprises at least the following two chemical steps:
1) an etherification is p (5) below:
in which the radicals T and n have the same meanings indicated in formula (1)
in water and/or at least one organic solvent with a boiling point of greater than
200°C by reacting, in the presence of at least one phase-transfer agent and of
at least one base, an alkenyl halide of formula (6) below:
in which X denotes a halogen atom, preferably bromine or chlorine, and R
denotes hydrogen or methyl,
2) a Claisen rearrangement is performed on the compound thus obtained of
formula (7) below:
(7)
in which T, n and have the same meanings indicated in formula (1), by
heating the reaction mixture to a temperature of greater than 170°C in the
presence of at least one organic solvent with a boiling point of greater than
200°C.
5. Process according to any one of Claims 1 to 4 , in which the organic solvent(s)
used in the Claisen rearrangement step and optionally in the etherification step i)
of Claim 2 are water-immiscible and have a boiling point of greater than 200°C,
preferably between 200 and 270°C and more preferentially between 200 and
220°C.
6. Process according to any one of Claims 1 to 5, in which:
- in the etherification step, the temperature of the reaction mixture is between
20°C and 150°C and more particularly between 60°C and 90°C,
- in the Claisen rearrangement step, the temperature of the reaction mixture is
between 170°C and 250°C and more particularly between 200°C and 220°C.
7. Process according to any one of Claims 1 to 6, in which the starting
2-hydroxyphenylbenzotriazole compound is chosen from 2-(2-hydroxy-5-
methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole and
2-(2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole and more preferentially
2-(2-hydroxy-5-methylphenyl)benzotriazole.
8. Process according to any one of Claims 1 to 7 , in which the alkenyl halide is
chosen from 1-chloro-2-propene (allyl chloride), 1-bromo-2-propene (ally!
bromide), 1-chloro-2-methyl-2-propene (methallyl chloride) and 1-bromo-2-
methyl-2-propene (methallyl bromide) and more preferentially methallyl chloride.
9. Process according to any one of Claims 1 to 8, in which, in the etherification
step:
- the alkenyl halide is present in a ratio that may range from 1.05 to
1.7 equivalents relative to the starting 2-hydroxyphenylbenzotriazole,
- the concentration of the starting 2-hydroxyphenylbenzotriazole compound in
the reaction medium ranges from 5% to 80% by weight and preferentially from
20% to 50% by weight relative to the total weight of the reaction medium.
10. Process according to any one of Claims 1 to 9, in which the phase-transfer
agent(s) are chosen from tetrabutylammonium halides, tetrabutylammonium
hydrogenosulfate, benzyltrimethylammonium chloride and preformed catalysts
between tributylamine and the alkenyl halides and more particularly chosen
from tetrabutylammonium bromide and the preformed catalyst between
tributylamine and methallyl chloride.
11. Process according to any one of Claims 1 to 10, in which the phase-transfer
agent(s) are present in a ratio ranging from 3 mol% to 15 mol% relative to the
starting 2-hydroxyphenylbenzotriazole compound.
12. Process according to any one of Claims 1 to 1, in which the base is chosen
from alkaline-earth metal bases and preferably from sodium bicarbonate,
sodium carbonate, potassium bicarbonate, potassium carbonate, sodium
hydroxide and potassium hydroxide, and more particularly potassium carbonate.
13. Process according to any one of Claims 1 to 12, in which the base is present
in a ratio ranging from 0.7 to 1.5 equivalents relative to the starting
2-hydroxyphenylbenzotriazole.
14. Process according to any one of Claims 1 to 13, in which the organic
solvent(s) used in the etherification step, step ii) of Claim 2 and in the Claisen
rearrangement step are chosen from benzyl alcohol, diethylene glycol
monobutyl ether, diphenyl ether, tetralin, methylnaphthalene and the
biphenyl/diphenyl ether mixture, and more particularly benzyl alcohol.
15. Process according to any one of Claims 2 to 14, in which the
recrystallization solvent(s) are chosen from isopropanol, methanol, ethanol and
benzyl alcohol or mixtures thereof, and more particularly isopropyl alcohol.
16. Process for preparing a siloxane compound containing a benzotriazole
function, characterized in that it comprises at least the following steps:
a) a 2-hydroxyalkenylphenylbenzotriazole compound is prepared according to
the process as defined in any one of Claims 1 to 15;
b) a hydrosilylation reaction is performed on the said 2-hydroxyalkenylphenylbenzotriazole
compound thus obtained in the presence of a catalyst and of a
suitable solvent with a siloxane containing an SiH function.
17. Process according to Claim 16, characterized in that a siloxane compound
containing a 2-hydroxyphenylbenzotriazole function of formula (4) below is
prepared:
(A)— (D) (4)
in which group (A) represents the silicone part of formula (4) with:
- R, which may be identical or different, denote a linear or branched and
optionally halogenated or unsaturated Ci-C30 alkyl radical, a C -Ci 2 aryl radical,
a linear or branched C1-C10 alkoxy radical or a group -OSi(CH3)3 ;
- a is an integer between 0 and 2 inclusive;
and in which group (D) represents a group of formula (4) with:
- n is an integer between 0 and 3 inclusive;
- T, which may be identical or different, are chosen from linear or branched
C C alkyl radicals, halogens and linear or branched C1-C4 alkoxy radicals;
- R represents hydrogen or a methyl radical;
in addition to the units of formula (A), the siloxane compound may comprise
units of formula:
in which:
- R has the same meaning as in formula (4);
- b = 1, 2 or 3,
and in that the said process comprises at least the following steps:
a) a 2-hydroxyalkenylphenylbenzotriazole compound of formula (1) is prepared:
(1)
in which R , T and n have the same meaning as in formula (4), according to the
process as defined according to any one of Claims 4 to 15;
b) a hydrosilylation reaction is performed on the said compound of formula (1)
with a siloxane containing an SiH function of formula (2) below:
H- Si)-0 (3-a) 2
(2)
R
in which R and a have the same meaning as in formula (3), in the presence of a
suitable catalyst and a suitable solvent.
18. Process accord that the compound
Drometrizole Trisilox following formula:
(c)
and in that the said process comprises at least the following steps:
a) the compound 2-(2H-1 ,2,3-benzotriazol-2-yl)-4-methyl-6-(2-methylprop-2-
enyl)phenol is prepared according to the process as defined according to any
one of Claims 4 to 15;
b) a hydrosilylation reaction is performed on the said compound with the
siloxane containing an SiH function: 1, 1 ,1 ,3,5,5,5-heptamethyltrisiloxane in the
presence of a suitable catalyst and a suitable solvent.