CA1188710A - Phenolic antioxidants - Google Patents
Phenolic antioxidantsInfo
- Publication number
- CA1188710A CA1188710A CA000432090A CA432090A CA1188710A CA 1188710 A CA1188710 A CA 1188710A CA 000432090 A CA000432090 A CA 000432090A CA 432090 A CA432090 A CA 432090A CA 1188710 A CA1188710 A CA 1188710A
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- Prior art keywords
- tert
- methyl
- water
- alcohol
- product
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Abstract A process of purifying tris(1-hydroxy-3-methyl-6-tert. butyl phenyl) butane comprises crystallising it from an aromatic hydrocarbon having 6 to 9 carbon atoms to produce a product containing said hydrocarbon and removing at least part of the hydrocarbon from the product by washing it with a liquid consisting essentially of at least one water miscible alcohol and water.
Description
1 ~.32306 Phenolic Antioxidant THIS I~VENTIO~ relste6 to tris(l-hydroxy-3-methyl-6-tert.
butyl phenyl) butane, a phenolic antioxidant. More part~cularly, it concerns a process for producing that compound in a purifled form.
We first described a group of novel phenolic derlvatlves having important antioxidant properties, and a process for their preparation, in United Kingdom Patent No. 951,935. Among the compounds which we described was tris(l-hydroxy-3-methyl-6-tert. butyl phenyl) butane. It was produced by condensing crotonaldehyde with 3-methyl-6-tert. butyl phenol. The product has for many years been sold under the Trade Mark "Topanol" CA.
The product may be produced by carrying out the condensation in a solvent, ior example methanol, and in the presence of a condensing agent, for example hydrochloric acld. The crude product may be isolated as a solid and may then be washed with water, whereafter it may be recrystallised from toluene, for example. ~See for example, page 2 line~ 55-64 of the above specification3. In another embodiment, the product may be obtained by adding an entraining agent, preferably toluene, to the reaction mlxture, d'istilling the mixture to remove water of condensation and finally recovering the product by crystallisation from the remaining entrainlng agent. (See page 2, lines 23-3~ of the above specification).
-When the production of tris(l-hydroxy-3-methyl-6-tert. butyl phenyl~ butane include~ a final recrystallisation from a C6 to-Cg aromstic hydrocarbon for example toluene, the product may contain a quantity of the hydrocarbon in the crystals. For many antioxldant uses the presence of the said hydrocarbon may be acceptable but in some uses it may be desired to use a product from which the hydrocarbon has been at least partly removed. One way of producing the product ~ith a minimum aromatic hydrocarbon content is to subject the product to controlled heating, to remove some at least of the hydrocarbon present. Another way i8 to carry out a recrys~allisation from another solvent. Yet another way is to omit the crystallisation from the aromatlc hydrocarbon but this is a desirable feature of the well-establlshed production method.
~ ~
....
~387~1
butyl phenyl) butane, a phenolic antioxidant. More part~cularly, it concerns a process for producing that compound in a purifled form.
We first described a group of novel phenolic derlvatlves having important antioxidant properties, and a process for their preparation, in United Kingdom Patent No. 951,935. Among the compounds which we described was tris(l-hydroxy-3-methyl-6-tert. butyl phenyl) butane. It was produced by condensing crotonaldehyde with 3-methyl-6-tert. butyl phenol. The product has for many years been sold under the Trade Mark "Topanol" CA.
The product may be produced by carrying out the condensation in a solvent, ior example methanol, and in the presence of a condensing agent, for example hydrochloric acld. The crude product may be isolated as a solid and may then be washed with water, whereafter it may be recrystallised from toluene, for example. ~See for example, page 2 line~ 55-64 of the above specification3. In another embodiment, the product may be obtained by adding an entraining agent, preferably toluene, to the reaction mlxture, d'istilling the mixture to remove water of condensation and finally recovering the product by crystallisation from the remaining entrainlng agent. (See page 2, lines 23-3~ of the above specification).
-When the production of tris(l-hydroxy-3-methyl-6-tert. butyl phenyl~ butane include~ a final recrystallisation from a C6 to-Cg aromstic hydrocarbon for example toluene, the product may contain a quantity of the hydrocarbon in the crystals. For many antioxldant uses the presence of the said hydrocarbon may be acceptable but in some uses it may be desired to use a product from which the hydrocarbon has been at least partly removed. One way of producing the product ~ith a minimum aromatic hydrocarbon content is to subject the product to controlled heating, to remove some at least of the hydrocarbon present. Another way i8 to carry out a recrys~allisation from another solvent. Yet another way is to omit the crystallisation from the aromatlc hydrocarbon but this is a desirable feature of the well-establlshed production method.
~ ~
....
~387~1
2 H.32306 We have therefore devised an alternative process for producing tris(hydroxy-3-methyl-6-tert. butyl phenyl) butane of low aromatic hydrocarbon content, which represents a readily achieved modification of the well-proven existing process.
According to the present invention a process of purlfying tris(1-hydroxy-3-methyl-6-tert. butyl phenyl) butane compri~es crystallising it from an aromatic hydrocarbon having 6 to 9 carbon atoms to produce a product containing said hydrocarbon and removlng at least part of the hydrocarbon from the product by washing it w5th a liquid consisting essentially of at least one water-miscible alcohol and water.
The tris(l-hydroxy-3-methyl-6-tert. butyl phenyl) butane may be made by condensing crotonaldehyde with 3-methyl-6-tert. butyl phenol as described in UK Patent 951,935. Aldol may be used as an alternative to crotonaldehyde if desired. In forming the desired product three mo]ecules of 3-methyl-6-tert. butyl phenol condense with each-molecule of crotonaldehyde or aldol.
The alcohol (or alcohols lf more than one is employed) may be a monohydric, dihydrlc or trihydric alcohol and may have a s~raight- or branched-chain or cycloaliphatic structure. Preferably it contains a maximum of six carbon atoms, and while ethylene glycol and glycerol are believed to be suitable alcohols in appropriate circumstances, it is preferred that the alcohol be a Cl to C6 straight- or branched-chain or cycloaliphatic monohydric alcohol.
Preferred alcohols therefore include methanol, ethanol, n- and isopropanol, n-, ~ec. and tert. butanol, n-amyl alcohol and cyclohexanol. A~ong these, methanol, ethanol, isopropanol and tert.
butanol are preferred and methanol is particularly preferred. If desired, mixtures of alcohols may be employed, ior example in order to achieve a balance between the desirable relevant properties of the individual alcohols.
The water content of the liquid depends upon the alcohol or alcohols selected but normally (when miscibility permits) will lie in the range of 10 per cent to 90 percent by weight. When u6ing a Cl to C6 monohydric alcohol, the process may be operated to particular advantage by employing a mixture containing between
According to the present invention a process of purlfying tris(1-hydroxy-3-methyl-6-tert. butyl phenyl) butane compri~es crystallising it from an aromatic hydrocarbon having 6 to 9 carbon atoms to produce a product containing said hydrocarbon and removlng at least part of the hydrocarbon from the product by washing it w5th a liquid consisting essentially of at least one water-miscible alcohol and water.
The tris(l-hydroxy-3-methyl-6-tert. butyl phenyl) butane may be made by condensing crotonaldehyde with 3-methyl-6-tert. butyl phenol as described in UK Patent 951,935. Aldol may be used as an alternative to crotonaldehyde if desired. In forming the desired product three mo]ecules of 3-methyl-6-tert. butyl phenol condense with each-molecule of crotonaldehyde or aldol.
The alcohol (or alcohols lf more than one is employed) may be a monohydric, dihydrlc or trihydric alcohol and may have a s~raight- or branched-chain or cycloaliphatic structure. Preferably it contains a maximum of six carbon atoms, and while ethylene glycol and glycerol are believed to be suitable alcohols in appropriate circumstances, it is preferred that the alcohol be a Cl to C6 straight- or branched-chain or cycloaliphatic monohydric alcohol.
Preferred alcohols therefore include methanol, ethanol, n- and isopropanol, n-, ~ec. and tert. butanol, n-amyl alcohol and cyclohexanol. A~ong these, methanol, ethanol, isopropanol and tert.
butanol are preferred and methanol is particularly preferred. If desired, mixtures of alcohols may be employed, ior example in order to achieve a balance between the desirable relevant properties of the individual alcohols.
The water content of the liquid depends upon the alcohol or alcohols selected but normally (when miscibility permits) will lie in the range of 10 per cent to 90 percent by weight. When u6ing a Cl to C6 monohydric alcohol, the process may be operated to particular advantage by employing a mixture containing between
3 H.32306 50 and 90 per cent by weight of water. FurLhermore, within this range, a good balance between product yield on the vne hand and low aromatic hydrocarbon content of the product on the other, may be obtained by using an alcohol/water mi~ture containing between 65 and 85 percent by weight of water. Ideally, the liquid is so formulated as to maximise the hydrocarbon removal while minimising the ~olubility of the tris-phenolic compound in the liquid. The solubility of the compound in the alcohol itself increases, in the case of homologous monohydric alcohols, as the carbon number of the alcohol increases;
however, the solubility of the compound in water is very low.
Therefore, in order to limit the solubility of the compound in the washing liquid, the water content of the liquid should preferably be increased with increasing alcohol carbon number.
The washing of the crystals of tris (hydroxy-3-methyl-6-tert.
butyl phenyl) butane may conveniently be carried out at ambient temperature. Sincel however, the solubility of the phenolic compound in the alcohol and in water varies with temperature, it is possible to carry out the washing at an elevated temperature, ~ay 60C9 ~o enable the use of a different alcohol or a different water content, f~om that which is appropriate at ambient temperature - for example to make possible the use of less alcohol in the aqueous alcohol wash mixture.
The quantity of aqueous alcohol employed conveniently is such that its weight is 1 to 5 tlmes the weight of the phenollc compound. The optimum quaneity may be determined by experiment and depends upon such factors as the composition of the aqueous alcohol, the desired purity of the washed product and the wash procedure selected. Often the optimum quantity will be 2 to 3 tlmes the weight of the phenolic compound.
After the washing, the wet crystals may be subjected to drying, for example at an elevated temperature of 60C to 80~, to remove residual wash liquor.
The invention ~s illustrated by the following Examples, in which percentages are by weight.
246 g of 3-methyl-6-tert. butyl phenol ~1.5 moles), 175 g of methanol and 87.5 g of concentrated hydrochloric acid were heated
however, the solubility of the compound in water is very low.
Therefore, in order to limit the solubility of the compound in the washing liquid, the water content of the liquid should preferably be increased with increasing alcohol carbon number.
The washing of the crystals of tris (hydroxy-3-methyl-6-tert.
butyl phenyl) butane may conveniently be carried out at ambient temperature. Sincel however, the solubility of the phenolic compound in the alcohol and in water varies with temperature, it is possible to carry out the washing at an elevated temperature, ~ay 60C9 ~o enable the use of a different alcohol or a different water content, f~om that which is appropriate at ambient temperature - for example to make possible the use of less alcohol in the aqueous alcohol wash mixture.
The quantity of aqueous alcohol employed conveniently is such that its weight is 1 to 5 tlmes the weight of the phenollc compound. The optimum quaneity may be determined by experiment and depends upon such factors as the composition of the aqueous alcohol, the desired purity of the washed product and the wash procedure selected. Often the optimum quantity will be 2 to 3 tlmes the weight of the phenolic compound.
After the washing, the wet crystals may be subjected to drying, for example at an elevated temperature of 60C to 80~, to remove residual wash liquor.
The invention ~s illustrated by the following Examples, in which percentages are by weight.
246 g of 3-methyl-6-tert. butyl phenol ~1.5 moles), 175 g of methanol and 87.5 g of concentrated hydrochloric acid were heated
4 H.32306 together, with stirring, until the methanol refluxed gently and then 35 g of crotonaldehyde (0.5 mole) was added 810wly while the mixture was stirred. The resulting mixture was then held under reflux for a further one hour. A solution of anhydrous sodium carbonate (13 g in 150 ml water) was then added to neutralise the catalys~ acid.
Methanol was distilled from the stirred reaction mi~ture until the temperature reached 98C and then 750 g of toluene was slowly added to dissolve the crude tris(hydroxy-3-methyl-6-tert. butyl phenyl)butane. The mixture separated into two layers and the lower (aqueous) layer containing dissolved neutralisation products was drained off, the upper (organic) layer being maintained at about 85C.
The organic layer was now washed twice with 250 ml of water and finally the organic layer was allowed to cool to room temperature with stirring. The tris-phenolic product which crystallised out was filtered off and allowed to dry. The product was analysed and found to contain 1.2 per cent of water, 2.6 per cent of methanol and 11.1 per cent of toluene.
A 50-gm portion of thi6 primary product was subjected to washing with 200 ml of a methanol/water mixture, the phenolic compound and the mixture being mixed together over a period of 30 minutes before removal of the washed product by filtration. The product was now dried in a fan-assisted oven for 4 hours at a temperature of 69C.
Finally, the dried product was weighed and analysed for water, methanol and toluene, with the following results:-Uater in Product Product Analysls (% wt) Example Wash Liquld ~eight No.(% wt) (gm.) Water Methanol Toluene 1 24 42.9 1.0 3.7 0.3 2 56 44.0 0.3~ 0.5 2.7 3 75 43.7 0.24 0.6 2.0 A 50-~m portion of tris~hydro~y-3-methyl-6-tert. butyl phenyl) butane, prepared as described in the above E~amples ~the primary product~ foLlowing crystallisation from the organic layer),' ~1813'7~
H.32306 was washed for half-an-hour with 200 ml of aqueous isopropanol contain~ng 75 per cent of water and then separated by filtration.
Drying the solid for four hours at 70C yielded 47.4 gm of product which on analysis was found to contaln 0.27 per cent of ~ater, 9.3 per cent of isopropanol and only 0.4 per cent of toluene.
EXAMPLE _ The preceding Example was repeated using 50 gm of phenolic compound and 200 ml of aqueous tert. butanol containing 75 per cent of water. 50.0 gm of product was obtained, containing 0.23 per cent of water, 14.6 per cent of tèrt. butanol and only 0.7 per cent of toluene.
240 g of 3-methyl-6-tert. butyl phenol (1.5 moles), 175 g of methanol and 87.5 g of concentrated hydrochloric acid were heated together, with stirring, until the methanol refluxed gently and then 35 g of crotonaldehyde (0.5 mole) was added slowly while the mixture was stirred. The resulting mixture was then held under reflux for a further one hour. A solution of anhydrous sodium carbonate (13 g in 150 ml water) was then added to neutralise the catalyst acid.
~ Methanol was distilled from the stirred reaction mixture until ehe temperature reached 98C and then 750 g of toluene was slowly added to dissolve the crude tris(hydroxy-3-methyl-6-tert. butyl phenyl) butane. The mixture separated into two layers and the lower (aqueous) layer containing dlssolved neutralisation products was drained off, the upper (organic) layer being maintained at about 85C. - `
The organic layer was now washed twice with 250 ml of water and finally the organic layer was allowed to cool eo room temperature with stirring. The tris-phenollc product which crystallised out was removed. The product at this stage was found to contain 10.8 per cent of toluene and 1.5 per cent of water.
The crystals were now washed with 450 ml of aqueous methanol, containing 25 per cent by weight of water. After this wash treatment and subsequent drying for 4 hours in a fan-assisted oven at 68C, the crystals were now found to contain 2.5 per cent of water, 3.4 per cent of methanol and only 0.8 per ceDt of toluene.
Methanol was distilled from the stirred reaction mi~ture until the temperature reached 98C and then 750 g of toluene was slowly added to dissolve the crude tris(hydroxy-3-methyl-6-tert. butyl phenyl)butane. The mixture separated into two layers and the lower (aqueous) layer containing dissolved neutralisation products was drained off, the upper (organic) layer being maintained at about 85C.
The organic layer was now washed twice with 250 ml of water and finally the organic layer was allowed to cool to room temperature with stirring. The tris-phenolic product which crystallised out was filtered off and allowed to dry. The product was analysed and found to contain 1.2 per cent of water, 2.6 per cent of methanol and 11.1 per cent of toluene.
A 50-gm portion of thi6 primary product was subjected to washing with 200 ml of a methanol/water mixture, the phenolic compound and the mixture being mixed together over a period of 30 minutes before removal of the washed product by filtration. The product was now dried in a fan-assisted oven for 4 hours at a temperature of 69C.
Finally, the dried product was weighed and analysed for water, methanol and toluene, with the following results:-Uater in Product Product Analysls (% wt) Example Wash Liquld ~eight No.(% wt) (gm.) Water Methanol Toluene 1 24 42.9 1.0 3.7 0.3 2 56 44.0 0.3~ 0.5 2.7 3 75 43.7 0.24 0.6 2.0 A 50-~m portion of tris~hydro~y-3-methyl-6-tert. butyl phenyl) butane, prepared as described in the above E~amples ~the primary product~ foLlowing crystallisation from the organic layer),' ~1813'7~
H.32306 was washed for half-an-hour with 200 ml of aqueous isopropanol contain~ng 75 per cent of water and then separated by filtration.
Drying the solid for four hours at 70C yielded 47.4 gm of product which on analysis was found to contaln 0.27 per cent of ~ater, 9.3 per cent of isopropanol and only 0.4 per cent of toluene.
EXAMPLE _ The preceding Example was repeated using 50 gm of phenolic compound and 200 ml of aqueous tert. butanol containing 75 per cent of water. 50.0 gm of product was obtained, containing 0.23 per cent of water, 14.6 per cent of tèrt. butanol and only 0.7 per cent of toluene.
240 g of 3-methyl-6-tert. butyl phenol (1.5 moles), 175 g of methanol and 87.5 g of concentrated hydrochloric acid were heated together, with stirring, until the methanol refluxed gently and then 35 g of crotonaldehyde (0.5 mole) was added slowly while the mixture was stirred. The resulting mixture was then held under reflux for a further one hour. A solution of anhydrous sodium carbonate (13 g in 150 ml water) was then added to neutralise the catalyst acid.
~ Methanol was distilled from the stirred reaction mixture until ehe temperature reached 98C and then 750 g of toluene was slowly added to dissolve the crude tris(hydroxy-3-methyl-6-tert. butyl phenyl) butane. The mixture separated into two layers and the lower (aqueous) layer containing dlssolved neutralisation products was drained off, the upper (organic) layer being maintained at about 85C. - `
The organic layer was now washed twice with 250 ml of water and finally the organic layer was allowed to cool eo room temperature with stirring. The tris-phenollc product which crystallised out was removed. The product at this stage was found to contain 10.8 per cent of toluene and 1.5 per cent of water.
The crystals were now washed with 450 ml of aqueous methanol, containing 25 per cent by weight of water. After this wash treatment and subsequent drying for 4 hours in a fan-assisted oven at 68C, the crystals were now found to contain 2.5 per cent of water, 3.4 per cent of methanol and only 0.8 per ceDt of toluene.
Claims (7)
1. A process of purifying tris(1-hydroxy-3-methyl-6-tert. butyl phenyl) butane which comprises crystallising it from an aromatic hydrocarbon having 6 to 9 carbon atoms to produce a product containing said hydrocarbon and removing at least part of the hydrocarbon from the product by washing it with a liquid consisting essentially of at least one water miscible alcohol and water.
2. A process according to claim 1 in which the tris(1-hydroxy-3-methyl-6-tert. butyl phenyl) butane is produced by condensing 3 molecules of 3-methyl-6-tert. butyl phenol with crotonaldehyde or aldol.
3. A process for the production of tris(1-hydroxy-3-methyl-6-tert. butyl phenyl) butane which comprises condensing crotonaldehyde with 3-methyl-6-tert. butyl phenol in a 1:3 molar ratio, crystallising the solid product from toluene and washing the resulting crystals with a liquid consisting of at least one water miscible alcohol and water.
4. A process as claimed in claim 1 in which the alcohol is a C1 to C6 straight or branched chain or cycloaliphatic monohydric alcohol.
5. A process as claimed in claim 4 in which the alcohol is methanol, ethanol, isopropanol or tertiary butanol.
6. A process as claimed in claim 1 in which the water content of the wash liquid is in the range 10% to 90% by weight.
7. A process as claimed in claim 1, 2 or 3 in which after washing the crystals are subjected to drying at a temperature of 60°c to 80°C to remove residual wash liquid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000432090A CA1188710A (en) | 1983-07-08 | 1983-07-08 | Phenolic antioxidants |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000432090A CA1188710A (en) | 1983-07-08 | 1983-07-08 | Phenolic antioxidants |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1188710A true CA1188710A (en) | 1985-06-11 |
Family
ID=4125640
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000432090A Expired CA1188710A (en) | 1983-07-08 | 1983-07-08 | Phenolic antioxidants |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1188710A (en) |
-
1983
- 1983-07-08 CA CA000432090A patent/CA1188710A/en not_active Expired
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