CA1208234A - Process for the preparation of 3,5-dihydrocarbyl -4-hydroxybenzylmalonic acid esters - Google Patents
Process for the preparation of 3,5-dihydrocarbyl -4-hydroxybenzylmalonic acid estersInfo
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Abstract
PROCESS FOR PREPARING SUBSTITUTED BENZYL
MALONIC ACID ESTERS
Abstract of the Disclosure Esters of 3,5-dihydrocarbyl-4-hydroxybenzyl-malonic acid are prepared by reacting a 2,6-dihydro-carbyl-4-hydroxy or -halogen substituted-methylphenol with an ester of a 1,3-dicarboxylic acid in the presence of an alkali metal hydride or an alkaline earth metal hydride. The products are useful as antioxidants.
MALONIC ACID ESTERS
Abstract of the Disclosure Esters of 3,5-dihydrocarbyl-4-hydroxybenzyl-malonic acid are prepared by reacting a 2,6-dihydro-carbyl-4-hydroxy or -halogen substituted-methylphenol with an ester of a 1,3-dicarboxylic acid in the presence of an alkali metal hydride or an alkaline earth metal hydride. The products are useful as antioxidants.
Description
~L~8239~
Case 5039/5040 .. .. .
This invention relates to 3,5-dihydrocarbyl-4-hydroxybenzylmalonic acid esters and the preparation and 5 uses thereof as antioxidants for oxidizable organic materials when such materials are exposed to oxidative degradative conditions.
The materials of the invention are prepared by reacting a 2,6-dihydrocarbyl-4-substituted-methylphenol 10 with an ester of a 1,3-dicarboxylic acid in the presence of an alkali metal hydride or an alkaline earth metal hydride. Thus, in one embodiment of the invention there i8 provided a novel process for the preparation of 3,5-dihydrocarbyl-4-hydroxybenzylmalonic acid esters 15 which comprises reacting a 2,6-dihydrocarby1-4-hydroxy or -halogen substituted-methylphenol with an ester of a 1,3-dicarboxylic acid in the presence of an alkali metal hydride or an alkaline earth metal hydride.
Thus, in the present invention there i9 provided 20 a proce~s for the preparation of 3,5-dihydrocarbyl-4-hydroxybenzylmalonic acid esters having the general formula:
.
' :
.
.
I , ' ' j .
Case 5039/5040 .. .. .
This invention relates to 3,5-dihydrocarbyl-4-hydroxybenzylmalonic acid esters and the preparation and 5 uses thereof as antioxidants for oxidizable organic materials when such materials are exposed to oxidative degradative conditions.
The materials of the invention are prepared by reacting a 2,6-dihydrocarbyl-4-substituted-methylphenol 10 with an ester of a 1,3-dicarboxylic acid in the presence of an alkali metal hydride or an alkaline earth metal hydride. Thus, in one embodiment of the invention there i8 provided a novel process for the preparation of 3,5-dihydrocarbyl-4-hydroxybenzylmalonic acid esters 15 which comprises reacting a 2,6-dihydrocarby1-4-hydroxy or -halogen substituted-methylphenol with an ester of a 1,3-dicarboxylic acid in the presence of an alkali metal hydride or an alkaline earth metal hydride.
Thus, in the present invention there i9 provided 20 a proce~s for the preparation of 3,5-dihydrocarbyl-4-hydroxybenzylmalonic acid esters having the general formula:
.
' :
.
.
I , ' ' j .
- 2 -lH
Rl~ ~R2 l~ ~ (III) ' O
S . ~ ~ OR3 O=C~
which comprises reacting a 2,6-dihydrocarbyl-4-substi-tuted-methylpheno]. of the general formula:
Rl ~, R2 H2C \
with an ester of a 1,3-dicarboxylic acid of the general 15 formula:
O
R30CCH~COR4 ~ .
Z~823~
in the presence of an alkali metal hydride or sn alka-line earth metal hydride ~berein in tbe structural for-mulas above Rl and R2 are the same or diffetent and are hydrogen or hydrocarbyl radicals having up to at 5 least 40 carbon atoms with the provision that at least one of Rl or R2 must be other than hydrogen; R3 and R4 are the same or different and are linear or branched alkyl radicals having up to at least 20 carbon atoms with the provision that at least one of R3 or 10 R4 must be other than hydrogen and Y is hydroxy or halogen.
Representative examples of radicals described above are secondary radicals such as secondary butyl, secondary amyl, secondary octyl; tertiary radicals such 15 as tertiary butyl, tertiary hexyl and tertiary decyl;
alkyl radicals such as methyl, ethyl, propyl, butyl, nonyl, decyl, tetradecyl, hexadecyl, nonadecyl; aralkyl radicals such as methyl phenyl and pentyl phenyl, and Z cycloalkyl radicals such as cyclopentyl, cyclohexyl and 20 cycloheptyl radicals.
Representative examples of the Group I compounds are 2,6-di-t-butyl-4-chloroethylphenol, 2,6-di-t-butyl-4-bromomethylphenol, 2,6-di-t-butyl-4-iodomethylphenol, 2-methyl-6-isopropyl-4-chloromethylphenol, .
.
- , .
.
, .
~2~;313Z34 2-methyl-6-isopropyl-4-bromomethylphenol, 2-methyl-6-isopropyl-4-iodomethylphenol, 2-methy]-6-t-butyl-4-cbloromethylphenol, 2-methyl-6-t-butyl-4-bromomethylphenol, 2-methyl-6-t-butyl-4-iodomethylphenol, 2,6-diisopropyl-4-chloroethylphenol, 2,6-diisopropyl-4-bromomethylphenol, 2,6-diisopropyl-4-iodomethylphenol, 2-sec-butyl-4-chloromethylphenol, 2-sec-butyl-4-bromomethylphenol, 2-sec-butyl-4-iodomethylphenol, 2-isopropyl-4-chloromethylphenol, 2-isopropyl-4-bromomethylphenol, 2-isopropyl-4-iodomethyiphenol, 2-t-butyl-4-chloromethylphenol, , 2-t-butyl-4-bromomethylphenol, 2-t-b~tyl-4-iodomethylphenol, 2-ethyl-6-t-butyl-4-chloromethylphenol, 2-ethyl-6-t-butyl-4-bromomethylphenol, 2-ethyl-6-t-butyl-4-iodomethylphenol, 2,6-diheptyl-4-chloromethylphenol, !
2',6-diheptyl-4-bromomethylphenol, 2,6-diheptyl-4-iodometbylphenol, 2-ethyl-S-methyl-4-chloromeChylphenol, 25 . 2-ethyl-6-methyl-4-bromomethylphenol, 2-ethyl-6-methyl-4-iodomethylphenol, . , .
8;~3~
.. 5 _ .
2-t-butyl-6-heptyl-4-chloromethylphenol, 2-t-butyl-6-heptyl-4-bromomethylphenol, 2-t-butyl-6-heptyl-4-iodomethylphenol, 2-methyl-6-ethyl-4-chloromethylphenol, 2-methyl-6-ethyl-4-bromomethylphenol, 2-methyl-6-ethyl-4-iodomethylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, 2-methyl-6-isopropyl-4-hydroxymethylphenol, 2-methyl-6-t-butyl-4-hydroxymethylphenol, 2,6 diisopropyl-4-hydroxymethylphenol, 2-sec-butyl-4-hydroxymethylphenol, 2-isopropyl-4-hydroxymethylphenol, 2-t-butyl-4-hydroxymethylphenol, 2-ethyl-6-t-butyl-4-hydroxymethylphenol, 2,6-diheptyl-4-hydroxymethylphenol, 2-ethyl-6-methyl-4-hydroxymethylphenol, 2-t-butyl-6-heptyl-4-hydroxymethylphenol, 2-methyl-6-ethyl-4-hydroxymethylphenol, and the like.
. 20 Representative examples of Group II esters of 1,3-dicarboxylic acid compounds are malonic acid, dimethyl ester, ~ :
malonic acid, diethyl ester, malonic acid, diisopropyl ester, malonic acid, di-n-hexyl ester, malonic acid, dioctyl ester, , ~, ~ , \
;
malonic acid, didodecyl eYter, malonic acid, ethyl, methyl diester, malonic acid, ethyl, isopropyl diester, malonic acid, n-butyl, ethyl diester,.
S malonic acid, n-butyl, dodecyl diester, malonic acid, octyl, ethyl diester, malonic acld, ethyl monoester, malonic acid, n-propyl monoester, malonic acid, n-butyl monoester, malonic acid, n-hexyl monoester, malonic acid, octyl monoester, malonic acid, dodecyl monoester, and the like.
Representative examples of Group III benzylated malonic acid esters functioning as antioxidants, are lS 3,S-di-t-butyl-4-hydroxybenzylmalonic acid, ~
dimethyl ester,
Rl~ ~R2 l~ ~ (III) ' O
S . ~ ~ OR3 O=C~
which comprises reacting a 2,6-dihydrocarbyl-4-substi-tuted-methylpheno]. of the general formula:
Rl ~, R2 H2C \
with an ester of a 1,3-dicarboxylic acid of the general 15 formula:
O
R30CCH~COR4 ~ .
Z~823~
in the presence of an alkali metal hydride or sn alka-line earth metal hydride ~berein in tbe structural for-mulas above Rl and R2 are the same or diffetent and are hydrogen or hydrocarbyl radicals having up to at 5 least 40 carbon atoms with the provision that at least one of Rl or R2 must be other than hydrogen; R3 and R4 are the same or different and are linear or branched alkyl radicals having up to at least 20 carbon atoms with the provision that at least one of R3 or 10 R4 must be other than hydrogen and Y is hydroxy or halogen.
Representative examples of radicals described above are secondary radicals such as secondary butyl, secondary amyl, secondary octyl; tertiary radicals such 15 as tertiary butyl, tertiary hexyl and tertiary decyl;
alkyl radicals such as methyl, ethyl, propyl, butyl, nonyl, decyl, tetradecyl, hexadecyl, nonadecyl; aralkyl radicals such as methyl phenyl and pentyl phenyl, and Z cycloalkyl radicals such as cyclopentyl, cyclohexyl and 20 cycloheptyl radicals.
Representative examples of the Group I compounds are 2,6-di-t-butyl-4-chloroethylphenol, 2,6-di-t-butyl-4-bromomethylphenol, 2,6-di-t-butyl-4-iodomethylphenol, 2-methyl-6-isopropyl-4-chloromethylphenol, .
.
- , .
.
, .
~2~;313Z34 2-methyl-6-isopropyl-4-bromomethylphenol, 2-methyl-6-isopropyl-4-iodomethylphenol, 2-methy]-6-t-butyl-4-cbloromethylphenol, 2-methyl-6-t-butyl-4-bromomethylphenol, 2-methyl-6-t-butyl-4-iodomethylphenol, 2,6-diisopropyl-4-chloroethylphenol, 2,6-diisopropyl-4-bromomethylphenol, 2,6-diisopropyl-4-iodomethylphenol, 2-sec-butyl-4-chloromethylphenol, 2-sec-butyl-4-bromomethylphenol, 2-sec-butyl-4-iodomethylphenol, 2-isopropyl-4-chloromethylphenol, 2-isopropyl-4-bromomethylphenol, 2-isopropyl-4-iodomethyiphenol, 2-t-butyl-4-chloromethylphenol, , 2-t-butyl-4-bromomethylphenol, 2-t-b~tyl-4-iodomethylphenol, 2-ethyl-6-t-butyl-4-chloromethylphenol, 2-ethyl-6-t-butyl-4-bromomethylphenol, 2-ethyl-6-t-butyl-4-iodomethylphenol, 2,6-diheptyl-4-chloromethylphenol, !
2',6-diheptyl-4-bromomethylphenol, 2,6-diheptyl-4-iodometbylphenol, 2-ethyl-S-methyl-4-chloromeChylphenol, 25 . 2-ethyl-6-methyl-4-bromomethylphenol, 2-ethyl-6-methyl-4-iodomethylphenol, . , .
8;~3~
.. 5 _ .
2-t-butyl-6-heptyl-4-chloromethylphenol, 2-t-butyl-6-heptyl-4-bromomethylphenol, 2-t-butyl-6-heptyl-4-iodomethylphenol, 2-methyl-6-ethyl-4-chloromethylphenol, 2-methyl-6-ethyl-4-bromomethylphenol, 2-methyl-6-ethyl-4-iodomethylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, 2-methyl-6-isopropyl-4-hydroxymethylphenol, 2-methyl-6-t-butyl-4-hydroxymethylphenol, 2,6 diisopropyl-4-hydroxymethylphenol, 2-sec-butyl-4-hydroxymethylphenol, 2-isopropyl-4-hydroxymethylphenol, 2-t-butyl-4-hydroxymethylphenol, 2-ethyl-6-t-butyl-4-hydroxymethylphenol, 2,6-diheptyl-4-hydroxymethylphenol, 2-ethyl-6-methyl-4-hydroxymethylphenol, 2-t-butyl-6-heptyl-4-hydroxymethylphenol, 2-methyl-6-ethyl-4-hydroxymethylphenol, and the like.
. 20 Representative examples of Group II esters of 1,3-dicarboxylic acid compounds are malonic acid, dimethyl ester, ~ :
malonic acid, diethyl ester, malonic acid, diisopropyl ester, malonic acid, di-n-hexyl ester, malonic acid, dioctyl ester, , ~, ~ , \
;
malonic acid, didodecyl eYter, malonic acid, ethyl, methyl diester, malonic acid, ethyl, isopropyl diester, malonic acid, n-butyl, ethyl diester,.
S malonic acid, n-butyl, dodecyl diester, malonic acid, octyl, ethyl diester, malonic acld, ethyl monoester, malonic acid, n-propyl monoester, malonic acid, n-butyl monoester, malonic acid, n-hexyl monoester, malonic acid, octyl monoester, malonic acid, dodecyl monoester, and the like.
Representative examples of Group III benzylated malonic acid esters functioning as antioxidants, are lS 3,S-di-t-butyl-4-hydroxybenzylmalonic acid, ~
dimethyl ester,
3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diethyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diisopropyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, di-n-hexyl ester, '. 3,5-di~t-butyl-4-hydroxybenzylmalonic acid, ~ dioctyl ester, i 25 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, didodecyl ester, '. .
., :, ' !
., j ';
.
_ _ , :
' \
~' ' ' : ' ~' ' :
-~ ~Z~823~
. 7 _ : 3,5-di t-butyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, -`
3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl, isopropyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, dodecyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, methyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ' ethyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-propyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-hexyl monoester, 3,5-di-t-butyl-4-bydroxybenzylmalonic acid, octyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ' ~`
.dodecyl monoester, 3-ethyl-5-ethyl-4-hydroxybenzylmalonic acid, .
dioctyl e3ter, ~ :.
, .
. . .
`' ~ . ' :
~ lZ~3Z3~
.
3-n-butyl-5-octyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, 3-ethyl-5-methyl-4-hydroxybenzylmalonic acid, ethyl monoester, 3,5-dioctyl-4-hydroxybenzylmalonic acid, octyl monoester, and tbe like.
In general, any of the alkali metal hydrides or alkaline earth metal hydrides may be used in the prsc-tice of the present process. These include sodium 10 hydride, potassium hydride, lithium hydrlde, magnesium hydride, calcium hydride, and the like. Sodium hydride is preferred.
The process of the invention is carried out by reacting the 2,6-dihydrocarbyl-4-hydroxymethylphenol or 15 the 2,6-dihydrocarbyl-4-halomethylphenol starting material with at least 1 molsr equivalent of malonic acid ester reactant although an exces3 of ester reactant can be used. A preferred range of malonic acid ester reactant to halometbylphenol reactant or hydroxymethyl-20phenol reactant is from about 1 to 10 moles of ester permole of halomethylphenol or hydroxymethylphenol reactant.
At least 1 mole of hydride per mole of halo-methylphenol or hydroxymethylphenol reactant should be used in the proces~ of the invention, although an amount 25 of hydride up to about 50 moles of hydride per mole of '~ , ' ' " ' ,, ` ' ~.
' . .
. ;:,., ~ .. ;. . ' , g the substituted methylphenol reactant can be used, if desired.
The reaction is advantageously conducted at a temperature of from 50C. to 500C. While lower 5 temperatures can be used, the reaction rates are generally correspondingly lower. Temperatures above 500C. can be used, but excessive decomposition of the reaction components can occur. Reflux temperature at atmospheric pressure is effective and preferred.
Typically, the reaction can be cooducted at atmospberic pressure. However, higher pressures up to about 1000 psig may be used, if desired.
i The use of a solvent for the reaction mixture is not generally required, especially if ~n excess of 15 malonic acid ester reactant is used. However, if desired, a solvent which is inert under the reaction conditions, i.e., those solvents which do not enter into the reaction, may be added to the reaction vessel.
Useful solvents comprise aprotic solvents which include 20 ethers ~uch as diethyl ether, dibutyl ether, l-ethoxy-hexane, tetrahydrouran, 1,4-dioxane, 1,3-dioxolane, diglyme, 1,2-diethoxyethane, and tertiary amines such as pyridine, N-ethylpiperidine, triethylamine, tributyl-amine, N,N-diphenyl-N-methylamine, N,N-dimethylalanine, 25 etc. Especially useful solvents are dipolar aprotic solvents such aa dimethyl sulfoxide, N,N-dimethylforma-, ' i i:
., ! .
r . .
' - , ' i2~3Z34 - ld -mide, N,N-dimethylacetamide, dimethyl sulfone, tetra-methylene sùlfone, N-methy~lpyrrolidinone, acetonitrile and like materials. Other solvents which are inert under the reaction conditions may be used: for example, 5 low boiling hydrocarbons, halogenated hydrocarbons, examples of which are benzene, tolueoe, tetrachloro-ethane, the chlorinated benzenes, the chlorinated toluenes, etc., and lower alkanols having up to about 6 carbon atoms. These include methanol, ethanol, n-pro-10 panol, igopropyl alcohol, n-butanol, sec-butyl alcohol, t-butyl alcohol, n-pentanol, isopentyl alcohol, n-hexanol and isohexyl alcohol.
The amount of solvent can be expressed as a volume ratio of ~olvent to halomethylphenol reactant or 15 hydroxymethylphenol r3actant. Suitable volume ratios of solvent to halomethylphenol reactsnt or hydroxy-methylphenol reactant can be from 0/1 to 500/1 and preferably from 1/1 to 300/1.
The mode of addition in the process i9 not par-20 ticularly critical. Accordingly, it i9 convenient toadd the halomethylphenol reactant or the hydroxymethyl-phenol reactant to a mixture of the other materials, add 1`
the malonic acid ester compound to a mixture of the other material~, add the reactants to a mixture of the 25 substituted methylphenol and solvent, introduce all :
.
. I , ' .
' . ' ' `
.
~Z~ 34 ingredients simultaneously into the reaction zone, or the like.
The process should be carried out for the time sufficient to convert substantially all of the halo-methylphenol reactant or the hydroxymethylphenol to the corresponding benzylated malonic acid ester. The length of time for optimum yield will depend primarily upon the reaction temperature and the particular solvent, if any, used in the reaction. In general, excellent yields of the benzylated malonic acid ester are obtained in from about two to twenty-four hours.
Although not required, the process can be con-ducted irl a substantially anhydrou~ reaction system, and accordingly, the components of the reaction system are brought together and maintained under a substantially dry, inert atmosphere. hy "substantially anbydrous" is meant a reaction system wherein the total amount of water present is no more than about 5 percent by weight, based on the reaction mixture. When the amount of water in the system exceeds this, both reaction rate and yield oE product decrea~e.
The process may readily be conducted in a batch-wise, semi-batch or continuous manner and in conven-tional equipment.
Under the reaction conditions, elimination of the hydroxyl group or hnlide occurs yieldlng a quinone . .
, .
' ~ .
,`
~L2C~Z34 methide intermediate which undergoes nucleophilic attack by the malonic acid ester leactant to form the desired benzylated malonic acid ester product. Some bis-hydroxyphenyl)methane and benzyl ether by-products may 5 also be formed.
The benzylated malonic acid ester product is easily separated from the reaction mixture by such means as distillation, extraction, crystallization and other methods obvious to tbose skilled in the chemical pro-10 cessing art.
The benzylated malonic acid ester products pre-pared by the process of this invention have antioxidant properties and are capable of stabilizing polymers nor-mally subject to oxidative degradation when incorporated into the polymers using conventional techniques such as by addition to polymer lattices; or by addition to solid polymers on a mill or in a Banbury. Further, the novel compounds of this invention are effective antioxidants in both unleaded and leaded gasolines made from a wide 20 variety of base stocks and for engine and industrial oils which are derived from crude petroleum or produced synthetically.
The practice of this invention will be still further apparent by the following illustrative examples.
..~
3g~
Example I
A dimethylformamide solution (25 mmols) of j diethyl sodiomalonate (generated by treating a dimethyl-formamide solution of 2.4 g; 15 mmols diethyl malonate 5 with 0.72 g; 30 mmols oil-free sodium hydride) was added with stirring under a nitrogen atmosphere to a dimethyl-formamide solution (25 mLs~ oi 2,6-di-t-butyl-4-chloro-methylphenol (2.49 g; 10 mmols). The reaction mixture was heated to a temperature of 125C and held at that 10 temperature for 3 hours nnd then poured into cold 2N
hydrochloric acid (100 mLs). The aqueous reaction r slurry was extracted with dietbyl ether (3 x 30 mLs).
The combined organic extract was dried (MgS04) and concentrated to give 2.44 g; 39% by VPC of 3,5-di-t-15 butyl-4-hydroxybenzylmalonic acid, diethyl ester.
Example II
To an ethanol solution (10 mLs) of 2,6-di-t-butyl-4-hydroxymethylphenol (2.63 g; 10 mmols) and ethanol solution (15 mmols) of diethyl sodiomalonate 20 (generated by treating an ethanol solution of 1.6 g; 10 mmols diethyl malonate with 0.48 g; 20 mmols oil-free sodium hydride) was added with stirring under a nitrogen atmosphere. The reaction mixture was heated at reflux for 16 hours and then poured into cold 2N hydrochloric 25 acid (100 mLs). The aqueous reaction slurry was ex-I tracted with diethyl ether (3 x 30 mLs). The combined .1 . i I
, ~ ~21D~Z3~
organic,extract was dried (MgS04) and concentrated to give 1.42 g; 39% by VPC of.3,5-di-t-butyl-4-hydroxy~-benzylmalonic scid, ethyl ester.
'.
.
~ .
'
., :, ' !
., j ';
.
_ _ , :
' \
~' ' ' : ' ~' ' :
-~ ~Z~823~
. 7 _ : 3,5-di t-butyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, -`
3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl, isopropyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, dodecyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, methyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ' ethyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-propyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-hexyl monoester, 3,5-di-t-butyl-4-bydroxybenzylmalonic acid, octyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ' ~`
.dodecyl monoester, 3-ethyl-5-ethyl-4-hydroxybenzylmalonic acid, .
dioctyl e3ter, ~ :.
, .
. . .
`' ~ . ' :
~ lZ~3Z3~
.
3-n-butyl-5-octyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, 3-ethyl-5-methyl-4-hydroxybenzylmalonic acid, ethyl monoester, 3,5-dioctyl-4-hydroxybenzylmalonic acid, octyl monoester, and tbe like.
In general, any of the alkali metal hydrides or alkaline earth metal hydrides may be used in the prsc-tice of the present process. These include sodium 10 hydride, potassium hydride, lithium hydrlde, magnesium hydride, calcium hydride, and the like. Sodium hydride is preferred.
The process of the invention is carried out by reacting the 2,6-dihydrocarbyl-4-hydroxymethylphenol or 15 the 2,6-dihydrocarbyl-4-halomethylphenol starting material with at least 1 molsr equivalent of malonic acid ester reactant although an exces3 of ester reactant can be used. A preferred range of malonic acid ester reactant to halometbylphenol reactant or hydroxymethyl-20phenol reactant is from about 1 to 10 moles of ester permole of halomethylphenol or hydroxymethylphenol reactant.
At least 1 mole of hydride per mole of halo-methylphenol or hydroxymethylphenol reactant should be used in the proces~ of the invention, although an amount 25 of hydride up to about 50 moles of hydride per mole of '~ , ' ' " ' ,, ` ' ~.
' . .
. ;:,., ~ .. ;. . ' , g the substituted methylphenol reactant can be used, if desired.
The reaction is advantageously conducted at a temperature of from 50C. to 500C. While lower 5 temperatures can be used, the reaction rates are generally correspondingly lower. Temperatures above 500C. can be used, but excessive decomposition of the reaction components can occur. Reflux temperature at atmospheric pressure is effective and preferred.
Typically, the reaction can be cooducted at atmospberic pressure. However, higher pressures up to about 1000 psig may be used, if desired.
i The use of a solvent for the reaction mixture is not generally required, especially if ~n excess of 15 malonic acid ester reactant is used. However, if desired, a solvent which is inert under the reaction conditions, i.e., those solvents which do not enter into the reaction, may be added to the reaction vessel.
Useful solvents comprise aprotic solvents which include 20 ethers ~uch as diethyl ether, dibutyl ether, l-ethoxy-hexane, tetrahydrouran, 1,4-dioxane, 1,3-dioxolane, diglyme, 1,2-diethoxyethane, and tertiary amines such as pyridine, N-ethylpiperidine, triethylamine, tributyl-amine, N,N-diphenyl-N-methylamine, N,N-dimethylalanine, 25 etc. Especially useful solvents are dipolar aprotic solvents such aa dimethyl sulfoxide, N,N-dimethylforma-, ' i i:
., ! .
r . .
' - , ' i2~3Z34 - ld -mide, N,N-dimethylacetamide, dimethyl sulfone, tetra-methylene sùlfone, N-methy~lpyrrolidinone, acetonitrile and like materials. Other solvents which are inert under the reaction conditions may be used: for example, 5 low boiling hydrocarbons, halogenated hydrocarbons, examples of which are benzene, tolueoe, tetrachloro-ethane, the chlorinated benzenes, the chlorinated toluenes, etc., and lower alkanols having up to about 6 carbon atoms. These include methanol, ethanol, n-pro-10 panol, igopropyl alcohol, n-butanol, sec-butyl alcohol, t-butyl alcohol, n-pentanol, isopentyl alcohol, n-hexanol and isohexyl alcohol.
The amount of solvent can be expressed as a volume ratio of ~olvent to halomethylphenol reactant or 15 hydroxymethylphenol r3actant. Suitable volume ratios of solvent to halomethylphenol reactsnt or hydroxy-methylphenol reactant can be from 0/1 to 500/1 and preferably from 1/1 to 300/1.
The mode of addition in the process i9 not par-20 ticularly critical. Accordingly, it i9 convenient toadd the halomethylphenol reactant or the hydroxymethyl-phenol reactant to a mixture of the other materials, add 1`
the malonic acid ester compound to a mixture of the other material~, add the reactants to a mixture of the 25 substituted methylphenol and solvent, introduce all :
.
. I , ' .
' . ' ' `
.
~Z~ 34 ingredients simultaneously into the reaction zone, or the like.
The process should be carried out for the time sufficient to convert substantially all of the halo-methylphenol reactant or the hydroxymethylphenol to the corresponding benzylated malonic acid ester. The length of time for optimum yield will depend primarily upon the reaction temperature and the particular solvent, if any, used in the reaction. In general, excellent yields of the benzylated malonic acid ester are obtained in from about two to twenty-four hours.
Although not required, the process can be con-ducted irl a substantially anhydrou~ reaction system, and accordingly, the components of the reaction system are brought together and maintained under a substantially dry, inert atmosphere. hy "substantially anbydrous" is meant a reaction system wherein the total amount of water present is no more than about 5 percent by weight, based on the reaction mixture. When the amount of water in the system exceeds this, both reaction rate and yield oE product decrea~e.
The process may readily be conducted in a batch-wise, semi-batch or continuous manner and in conven-tional equipment.
Under the reaction conditions, elimination of the hydroxyl group or hnlide occurs yieldlng a quinone . .
, .
' ~ .
,`
~L2C~Z34 methide intermediate which undergoes nucleophilic attack by the malonic acid ester leactant to form the desired benzylated malonic acid ester product. Some bis-hydroxyphenyl)methane and benzyl ether by-products may 5 also be formed.
The benzylated malonic acid ester product is easily separated from the reaction mixture by such means as distillation, extraction, crystallization and other methods obvious to tbose skilled in the chemical pro-10 cessing art.
The benzylated malonic acid ester products pre-pared by the process of this invention have antioxidant properties and are capable of stabilizing polymers nor-mally subject to oxidative degradation when incorporated into the polymers using conventional techniques such as by addition to polymer lattices; or by addition to solid polymers on a mill or in a Banbury. Further, the novel compounds of this invention are effective antioxidants in both unleaded and leaded gasolines made from a wide 20 variety of base stocks and for engine and industrial oils which are derived from crude petroleum or produced synthetically.
The practice of this invention will be still further apparent by the following illustrative examples.
..~
3g~
Example I
A dimethylformamide solution (25 mmols) of j diethyl sodiomalonate (generated by treating a dimethyl-formamide solution of 2.4 g; 15 mmols diethyl malonate 5 with 0.72 g; 30 mmols oil-free sodium hydride) was added with stirring under a nitrogen atmosphere to a dimethyl-formamide solution (25 mLs~ oi 2,6-di-t-butyl-4-chloro-methylphenol (2.49 g; 10 mmols). The reaction mixture was heated to a temperature of 125C and held at that 10 temperature for 3 hours nnd then poured into cold 2N
hydrochloric acid (100 mLs). The aqueous reaction r slurry was extracted with dietbyl ether (3 x 30 mLs).
The combined organic extract was dried (MgS04) and concentrated to give 2.44 g; 39% by VPC of 3,5-di-t-15 butyl-4-hydroxybenzylmalonic acid, diethyl ester.
Example II
To an ethanol solution (10 mLs) of 2,6-di-t-butyl-4-hydroxymethylphenol (2.63 g; 10 mmols) and ethanol solution (15 mmols) of diethyl sodiomalonate 20 (generated by treating an ethanol solution of 1.6 g; 10 mmols diethyl malonate with 0.48 g; 20 mmols oil-free sodium hydride) was added with stirring under a nitrogen atmosphere. The reaction mixture was heated at reflux for 16 hours and then poured into cold 2N hydrochloric 25 acid (100 mLs). The aqueous reaction slurry was ex-I tracted with diethyl ether (3 x 30 mLs). The combined .1 . i I
, ~ ~21D~Z3~
organic,extract was dried (MgS04) and concentrated to give 1.42 g; 39% by VPC of.3,5-di-t-butyl-4-hydroxy~-benzylmalonic scid, ethyl ester.
'.
.
~ .
'
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing a 3,5-di-hydrocarbyl-4-hydroxybenzylmalonic acid ester of general formula:
(III) wherein:
R1 and R2, independently, represent a group selected from H and a hydrocarbyl radical of up to at least 40 carbon atoms, with the proviso that R1 and R2 do not both represent H; and R3 and R4, independently, represent a group selected from H, and a linear- and branched alkyl radical of up to at least 20 carbon atoms, with the proviso that R3 and R4 do not both represent H;
said process comprising:
reacting one molar equivalent of a 2,6-dihydrocarbyl-4-substituted-methylphenol of general formula:
(III) wherein R1 and R2 are as defined above and Y represents a group selected from -OH and a halogen atom, with at least one molar equivalent of an ester of a 1,3-dicarboxylic acid of general formula:
(II) wherein R3 and R4 are as defined above, in the presence of at least one molar equivalent of an alkali metal hydride or an alkaline earth metal hydride.
(III) wherein:
R1 and R2, independently, represent a group selected from H and a hydrocarbyl radical of up to at least 40 carbon atoms, with the proviso that R1 and R2 do not both represent H; and R3 and R4, independently, represent a group selected from H, and a linear- and branched alkyl radical of up to at least 20 carbon atoms, with the proviso that R3 and R4 do not both represent H;
said process comprising:
reacting one molar equivalent of a 2,6-dihydrocarbyl-4-substituted-methylphenol of general formula:
(III) wherein R1 and R2 are as defined above and Y represents a group selected from -OH and a halogen atom, with at least one molar equivalent of an ester of a 1,3-dicarboxylic acid of general formula:
(II) wherein R3 and R4 are as defined above, in the presence of at least one molar equivalent of an alkali metal hydride or an alkaline earth metal hydride.
2. The process of claim 1, wherein Y represents a group selected from C1, Br and I.
3. The process of claim 1, wherein said alkali metal hydride or alkaline earth metal hydride is selected from the group consisting of sodium hydride, barium hydride, lithium hydride, magnesium hydride and calcium hydride.
4. The process of claim 1, 2 or 3, wherein the molar ratio of the compound of general formula (II) to the compound of general formula (I) is from one to about 10:1.
5. The process of claim 1, 2 or 3, wherein the reaction is conducted at elevated temperature.
6. The process of claim 1, 2 or 3, wherein the reaction is carried out at a temperature of from about 50 to about 500°C.
7. The process of claim 1, 2 or 3, wherein the reaction is carried out under pressure in the range of from about atmospheric up to about 1,000 psig.
8. The process of claim 1, 2 or 3, wherein the reaction is carried out at a temperature of from about 50 to about 500°C and under pressure in the range of from about atmospheric up to about 1,000 psig.
9. The process of claim 1, wherein the reaction is carried out in the presence of a solvent which is inert under the reaction conditions.
10. The process of claim 9, wherein said solvent is an aprotic solvent.
11. The process of claim 10, wherein said aprotic solvent is a dipolar aprotic solvent.
12. The process of claim 11, wherein said dipolar aprotic solvent is selected from the group con-sisting of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfone, tetramethylene sulfone, N-methylpyrrolidinone and acetonitrile.
13. The process of claim 9, wherein said solvent is selected from the group consisting of low boiling hydrocarbons, halogenated hydrocarbons and lower alkanols having from one to about 6 carbon atoms.
14. The process of claim 9, 10 or 11, wherein the volume ratio of solvent to the compound of general formula (I) is from about one:one to about 500:one.
15. The process of claim 1, 2 or 3, wherein the reaction is carried out under a substantially dry inert atmosphere.
16. The process of claim 1, 3 or 9, wherein the compound of general formula (I) is selected from the group consisting of:
16. The process of claim 1, 3 or 9, wherein the compound of general formula (I) is selected from the group consisting of:
Claim 16...cont'd. (2) 2,6-di-t-butyl-4-chloroethylphenol, 2,6-di-t-butyl-4-bromomethylphenol, 2,6-di-t-butyl-4-iodomethylphenol, 2-methyl-6-isopropyl-4-chloromethylphenol, 2-methyl-6-isopropyl-4-bromomethylphenol, 2-methyl-6-isopropyl-4-iodomethylphenol, 2-methyl-6-t-butyl-4-chloromethylphenol, 2-methyl-6-t-butyl-4-bromomethylphenyl, 2-methyl-6-t-butyl-4-iodomethylphenol, 2,6-diisopropyl-4-chloroethylphenol, 2,6-diisopropyl-4-bromomethylphenol, 2,6-diisopropyl-4-iodomethylphenol, 2-sec-butyl-4-chloromethylphenol, 2-sec-butyl-4-bromomethylphenol, 2-sec-butyl-4-iodomethylphenol, 2-isopropyl-4-chloromethylphenol, 2-isopropyl-4-bromomethylphenol, 2-isopropyl-4-iodomethylphenol, 2-t-butyl-4-chloromethylphenol, 2-t-butyl-4-bromomethylphenol, 2-t-butyl-4-iodomethylphenol, 2-ethyl-6-t-butyl-4-chloromethylphenol, 2-ethyl-6-t-butyl-4-bromomethylphenol, 2-ethyl-6-t-butyl-4-iodomethylphenol, 2,6-diheptyl-4-chloromethylphenol, 2,6-diheptyl-4-bromomethylphenol, 2,6-diheptyl-4-iodomethylphenol, 2-ethyl-6-methyl-4-chloromethylphenol, 2-ethyl-6-methyl-4-bromomethylphenol, 2-ethyl-6-methyl-4-iodomethylphenol, 2-t-butyl-6-heptyl-4-chloromethylphenol, 2-t-butyl-6-heptyl-4-bromomethylphenol, 2-t-butyl-6-heptyl-4-iodomethylphenol, 2-methyl-6-ethyl-4-chloromethylphenol, 2-methyl-6-ethyl-4-bromomethylphenol, 2-methyl-6-ethyl-4-iodomethylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, 2-methyl-6-isopropyl-4-hydroxymethylphenol, 2-methyl-6-t-butyl-4-hydroxymethylphenol, 2,6-diisopropyl-4-hydroxymethylphenol, 2-sec-butyl-4-hydroxymethylphenol, 2-isopropyl-4-hydroxymethylphenol, 2-t-butyl-4-hydroxymethylphenol, 2-ethyl-6-t-butyl-4-hydroxymethylphenol, 2,6-diheptyl-4-hydroxymethylphenol, 2-ethyl-6 methyl-4-hydroxymethylphenol, 2-t-butyl-6-heptyl-4-hydroxymethylphenol, and 2-methyl-6-ethyl-4-hydroxymethylphenol.
17. The process of claim 1, 2 or 3, wherein the compound of general formula(II) is selected from the group consisting of:
malonic acid, dimethyl ester, malonic acid, diethyl ester, malonic acid, diisopropyl ester, malonic acid, di-n-hexyl ester, malonic acid, dioctyl ester, malonic acid, didodecyl ester, malonic acid, ethyl, methyl diester, malonic acid, ethyl, isopropyl diester, malonic acid, n-butyl ethyl diester, malonic acid, n-butyl, dodecyl diester, malonic acid, octyl, ethyl diester, malonic acid, ethyl monoester, malonic acid, n-propyl monoester, malonic acid, n-butyl monoester, malonic acid, n-hexyl monoester, malonic acid, octyl monoester, and malonic acid, dodecyl monoester.
18. The process defined in claim 1, 3 or 9, wherein for the compounds of general formula (I) and (II), R1 to R4, respectively, represents groups as shown in the following table:
malonic acid, dimethyl ester, malonic acid, diethyl ester, malonic acid, diisopropyl ester, malonic acid, di-n-hexyl ester, malonic acid, dioctyl ester, malonic acid, didodecyl ester, malonic acid, ethyl, methyl diester, malonic acid, ethyl, isopropyl diester, malonic acid, n-butyl ethyl diester, malonic acid, n-butyl, dodecyl diester, malonic acid, octyl, ethyl diester, malonic acid, ethyl monoester, malonic acid, n-propyl monoester, malonic acid, n-butyl monoester, malonic acid, n-hexyl monoester, malonic acid, octyl monoester, and malonic acid, dodecyl monoester.
18. The process defined in claim 1, 3 or 9, wherein for the compounds of general formula (I) and (II), R1 to R4, respectively, represents groups as shown in the following table:
Claim 18....cont'd. (2) to produce compounds of general formula (III) selected from the group consisting of:
3,5-di-t-butyl-4-hydroxybenzylmalonic acid, dimethyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diethyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diiso-propyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, di-n-hexyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, dioctyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, didodecyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl, isopropyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, dodecyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, methyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-propyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-hexyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, dodecyl monoester, 3-ethyl-5-ethyl-4-hydroxybenzylmalonic acid, dioctyl ester, 3-n-butyl-5-octyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, 3-ethyl-5-methyl-4-hydroxybenzylmalonic acid, ethyl monoester, and 3,5-dioctyl-4-hydroxybenzylmalonic acid, octyl mono-ester, respectively.
3,5-di-t-butyl-4-hydroxybenzylmalonic acid, dimethyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diethyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diiso-propyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, di-n-hexyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, dioctyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, didodecyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl, isopropyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl, dodecyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, methyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl, ethyl diester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, ethyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-propyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-butyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, n-hexyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, octyl monoester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, dodecyl monoester, 3-ethyl-5-ethyl-4-hydroxybenzylmalonic acid, dioctyl ester, 3-n-butyl-5-octyl-4-hydroxybenzylmalonic acid, ethyl, methyl diester, 3-ethyl-5-methyl-4-hydroxybenzylmalonic acid, ethyl monoester, and 3,5-dioctyl-4-hydroxybenzylmalonic acid, octyl mono-ester, respectively.
19. A process for preparing a 3,5-di-hydrocarbyl-4-hydroxybenzylmalonic acid ester of general formula:
(III) wherein:
R1 and R2, independently, represent a group selected from H and a hydrocarbyl radical of up to at least 40 carbon atoms, with the proviso that R1 and R2 do not both represent H; and R3 and R4, independently, represent a group selected from H, and a linear- and branched alkyl radical of up to at least 20 carbon atoms, with the proviso that R3 and R4 do not both represent H;
said process comprising:
reacting a 2,6-dihydrocarbyl-4-(-OH or halogen atom)-substituted methylphenol of general formula:
(I) wherein R1 and R2 are as defined above and Y represents a group selected from -OH and a halogen atom, with an ester of a 1,3-dicarboxylic acid of general formula:
(II) wherein R3 and R4 are as defined above, in the presence of an alkali metal hydride or an alkaline earth metal hydride.
(III) wherein:
R1 and R2, independently, represent a group selected from H and a hydrocarbyl radical of up to at least 40 carbon atoms, with the proviso that R1 and R2 do not both represent H; and R3 and R4, independently, represent a group selected from H, and a linear- and branched alkyl radical of up to at least 20 carbon atoms, with the proviso that R3 and R4 do not both represent H;
said process comprising:
reacting a 2,6-dihydrocarbyl-4-(-OH or halogen atom)-substituted methylphenol of general formula:
(I) wherein R1 and R2 are as defined above and Y represents a group selected from -OH and a halogen atom, with an ester of a 1,3-dicarboxylic acid of general formula:
(II) wherein R3 and R4 are as defined above, in the presence of an alkali metal hydride or an alkaline earth metal hydride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000443682A CA1208234A (en) | 1983-12-19 | 1983-12-19 | Process for the preparation of 3,5-dihydrocarbyl -4-hydroxybenzylmalonic acid esters |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000443682A CA1208234A (en) | 1983-12-19 | 1983-12-19 | Process for the preparation of 3,5-dihydrocarbyl -4-hydroxybenzylmalonic acid esters |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1208234A true CA1208234A (en) | 1986-07-22 |
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ID=4126780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000443682A Expired CA1208234A (en) | 1983-12-19 | 1983-12-19 | Process for the preparation of 3,5-dihydrocarbyl -4-hydroxybenzylmalonic acid esters |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1208234A (en) |
-
1983
- 1983-12-19 CA CA000443682A patent/CA1208234A/en not_active Expired
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