CA2244082A1 - Synthesis of anionic cleaning agents - Google Patents
Synthesis of anionic cleaning agents Download PDFInfo
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- CA2244082A1 CA2244082A1 CA 2244082 CA2244082A CA2244082A1 CA 2244082 A1 CA2244082 A1 CA 2244082A1 CA 2244082 CA2244082 CA 2244082 CA 2244082 A CA2244082 A CA 2244082A CA 2244082 A1 CA2244082 A1 CA 2244082A1
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Abstract
There is provided a method of synthesis of a disulfated cleaning agent from a substituted cyclic anhydride, particularly a substituted succinic anhydride, having one or more carbon chain substituents comprising in total at least 5 carbon atoms comprising the following steps: (i) reduction of said substituted cyclic anhydride to form a diol; (ii) optionally, alkoxylation of said diol to form an alkoxylated diol; and (iii) sulfation of said diol to form a disulfate, wherein said reduction step comprises hydrogenation in the presence of a transition metal-containing hydrogenation catalyst. The hydrogenation is carried out under pressure.
Description
W O 97/28119 PCTrUS97/00082 Synthes;s of anion~c cleaninq aqents Technical field The present invention relates to an improved method for the synthesis of disulfated cleaning agents, for use in detergent compositions.
Backqround to the invention Specific use of dianionic surfactants, that is surfactants having two anionically charged groups, as detergent components has been previo~sly described. Disulfated surfactants, in particular 1,4 disulfated surfactants and alkoxylated forms thereof, are specific examples of such dianionic surfactants.
Disulfated surfactants have not to date found common use in the detergent industry because of the difficulty ~ssoci~ted in deriving a commercially viable route for their bulk preparation. Commercial viability is, in general terms, dictated by the need to employ inexpensive, readily available starting materials capable of translation into 'end product' via a synthetic route which is energy efficient, employs inexpensive, readily available reagents and provides high yields.
Known syntheses of disulfated surfactants, in general, use an alkyl or alkenyi succinic anhydride as the principal starting material. This is initiallysubjected to a reduction step from which a diol is obtained. Subse~uently the diol is su~ected to a sulfation step to give the disulfated product.
Optionally, an alkoxylation step may be introduced prior to the sulfation step such that alkoxylated disulfate cleaning agents are obtained.
As an example, US-A-3,634,269 describes phosphate-free detergent compositions containing 2-alkyl or alkenyl-1,4-butanediol disulfates.
Described therein, is their preparation by the reduction of alkenyl succinic anhydrides with lithium aluminium hydride to produce either alkenyl or alkyl diols which are then sulfated.
CA 02244082 l998-07-23 W O 97/28119 PCTnUS97/00082 Additionally, US-A-3,9~9,334 and US-A4,Q00,081 describe 2-hydrocarbyl-1,4-butanediol disulfates said to be suitable as lime soap dispersants Again, the method for synthesizing these disulfates involves the reduction of alkenyl succinic anhydrides with lithium aluminium hydride to produce either alkenyl or alkyl diols which are then sulfated.
US-A-3,832,408 and US-A-3,860,625 describe phosphate-free detergent compositions containing 2-alkyl or alkenyl-1,4-butanediol ethoxylate disulfates. Their preparation by the reduction of alkenyl succinic anhydrides with lithium aluminium hydride to produce either alkenyl or alkyl diols which are then ethoxylated prior to sulfation is described.
A problem associated with the known synthetic routes to 1,4 disulfated surfactants is that the reduction step involves the use of pyrophoric and expensive lithium aluminum hydride (LiAlH4) to reduce the anhydride to the 1,4-diol. Safe handling of pyrophoric ~l~alerials requires special process equipment which further adds to processing complexity and cost.
Additionally, aluminium salts which are formed in the process require special care in their dispossl.
The Applicants have now found an alternative method of carrying out thereduction step involving hydrogenation of the anhydride in the presence of a transition metal-containing hydrogenation catalyst. Thus use of lithium aluminium hydride, and the potential problems related thereto, may be avoided.
Summarv of the Invention According to the present invention there is provided a method of synthesis of a disulfated cleaning agent from a substituted cyclic anhydride having one or more carbon chain substituents comprising in total at least 5 carbon atoms comprising the following steps:
(i) reduction of said substituted cyclic anhydride to form a diol;
W O 97/28119 PCTrUS97/00082 (ii) optionally, alkoxylation of said diol to form an alkoxylated diol; and ~iii) sulfation of said diol or alkoxylated diol to form a disulfate wherein said reduction step comprises hydrogenation under pressure in the presence of a transition metai-containing hydrogenation catalyst.
[)etailed description of the invention There is provided a method for the synthesis of a disulfated cleaning agent from a substituted cyclic anhydride.
Cvclic anhvdride startin~ material The cyclic anhydride starting material has a ring structure and comprises an acid anhydride linkage. Cyclic anhydrides are generally formed by a ring forming condensation reaction of a single organic compound having a first carboxylic acid (-COOH) functional group and a second -COY functional group separated from the carboxylic acid functional group by at least two carbon atoms, wherein Y is usually an -OH, or halogen functionality.
A specific example of an organic compound which may be condensed to form a cyclic anhydride is maleic acid which on self-condensation provides maleic anhydride. Maleic anhydride is readily available commercially.
The ring structure of the cyclic anhydride starting material contains from 4 to 7 carbon atoms, preferably from 4 to 6 carbon atoms in the ring structure.
Most pr~rerably the cyclic anhydride starting material is based on succinic anhydride which has a 5-membered ring structure containing 4 carbon atoms in the ring.
The cyclic anhydride starting material is substituted by one or more carbon containing substituents, such that in total, these substitutents contain at least S carbon atoms, preferably from S to 25 carbon atoms, more preferably from 7 to 21 carbon atoms.
CA 02244082 l998-07-23 W O 97/28119 PCTrUS97/00082 In a preferred aspect all of the carbon chain substituent(s) comprise either alkyl or alkenyl chains, which may be branched or unbranched. In one preferred aspect they are essentially unbranched. In another preferred aspect the chains are primarily monobranched, that is more than 50% by weight of the chains are monobranched.
In one preferred aspect the substituted cyclic anhydride has a single carbon chain substituent. In another preferred aspect the substituted cyclic anhydride has two carbon chain substituents each having different points of attachment to the ring structure.
Substituted alkenylsuccinic and alkylsuccinic anhydrides are suitable starting materials herein. Preferred anhydrides of this type have the following structures:
R~ O R2 o R ~' ' \ R /\\~
Alkylsuccinic L ~ Alk~ny~succinic l ~
Anhydride ~~ Anhydride ~
O O
where R and R2 are either H or an alkyl group. In one preferred aspect R2 is H.
Linear alkenylsuccinic anhydrides may be obtained in high yield from the single stage 'ene reaction' of maleic anhydride with an alpha-olefin.
Branched alkenylsuccinic anhydrides may be obtained from the single stage 'ene reaction' of maleic anhydride with an internal olefin, such as those obtainable from the familiar SHOP ~tradename of the Shell Corporation) olefin making process. Preferably the substituted alkenylsuccinic or alkylsuccinic anhydride starting materials will be substantialiy pure and, in particular, dimeric impurities are preferably minimised. Thus, preferably the cyclic anhydride starting material contains less than 30% dimeric impurities, more preferably less than 10%, most preferably less than 5% or even less than 2.5 or 1% by weight. Such impurities can be minimised by conventional techniques within the limit of the skilled person, for example either by selection of appropriate reaction conditions in producing the cyclic anhydride starting material (such as low temperature) or by subsequent purification, for example by distillation.
Alkylsuccinic anhydride starting materials can be made by reducing alkenylsuccinic anhydrides. This reduction can be achieved under the conditions of the catalytic hydrogenation reduction step of the present invention.
The reduction steP
The first step of the synthetic method of the invention is the reduction of the substituted cyclic anhydride to form a diol. The reduction step comprises hydrogenation under pressure in the presence of a transition metal-containing hydrogenation catalyst.
It is an advantage of the present invention that under the conditions of the catalytic hydrogenation reduction step any alkene linkages are also reduced to alkyl linkages. Thus, if an alkenylsuccinic anhydride is used as the starting material it is reduced via a (single) reduction step to the diol havingalkyl chain substituents, as are desired. This contrasts with the situation where LiAlH4, which does not reduce alkene linkages, is used in the reduction step, wherein an extra step involving the reduction of the alkenyl succinic anhydride to the alkyl succinic anhydride (via e.g. Pd/hydrogen) must be employed to obtain the desired diol product.
~a) Hvdro~enation catalvst The hydrogenation catalyst acts functionally to enhance the efficiency of the reductive hydrogenation process. For use on a commercial scale it is desirable that the catalyst is easy to regenerate.
Preferably the catalyst contains a transition metal selected from the group consisting of the group VIA (particularly Cr), VIIA (particularly Mn), Vlll (particularly Fe, Co, Ni, Ru, Rh) and IB (particularly Cu) elements. Catalysts con~ai,ling mixtures of any of these transition metals are envisaged as are W O 97128119 PCT~US97/00082 catalysts containing other rnetais including the alkali and alkaline earth metals.
Copper-containing catalysts, particularly copper chromite (which is commercially available and relatively easy to regenerate~ are most ,urefe~, ed.
The hydrogenation catalyst may advantageously ~e supported on an inert support material. The support material generally comprises an oxide salt comprising a metal selected from the group consisting of aluminium, silicon and any mixtures thereof. Supports comprising aluminium oxide or silicon dioxide are especially preferred. Clay materials are also suitable supports.
~b) Process details The reductive hydrogenation step is carried out under pressure, and generally at elevated temperature. Usually a solvent is employed. This step can be carried out by a batch, continuous or vapor-phase process. A
continuous process is p,erer,~:d.
The pressure is typically from 1 x 105 to 1 x 107 Pa, more preferably from 1 x 1~6 to ~ x 106 Pa. The temperature is generally from 150 to 350~C, more preferabiy from 20t~ to 300~C. The time of reaction is generally from 30 minutes to 10 hours.
Suitable solvents include alcohols, particularly methanol, ethanol, propanol and butanol.
It is to appreciated that the exact process conditions used for any particular synthesis will be varied to achieve optimum results in accord with the usual process optimization steps which will be within the remit of the skilled person. In particular the process conditions will be adjusted to minimize the occurence of any competing side-reactions.
One possible problem derives from the incomplete reduction of the cyclic anhydride, such that lactones are formed. These are however, convertible to W O 97128119 PCTrUS97/~0082 diols by further catalytic hydrogenation. It may be advantageous to carry out the hydrogenation in two steps preferably as part of a continuous step-wise process, such that a lactone is formed in the first step followed by a second step in which the lactone is reduced to the diol. Conditions which favour lactone formation are high temperature (~300 ~C) and low pressures (~ 1 x 105 Pa). Any water formed during the hydrogenation will primarily be in the vapour phase, so that the anhydride is unlikely to be converted to a carboxylic acid which can inhibit the catalyst. The best conditions for diol formation from the lactone are lower temperatures (~220 ~C) and high pressures (~ 1 x 107 Pa), both of which conditions minimize the production of furan by-product.
Furans can be formed by a ring closure reaction of the diol product.
Generally any furan by-product should be present in an amount below ~% of the desired diol, preferably below 2%, most preferaL,ly below 1.5% or even below 1% by weight of the desired diol.
The tendency for such furans to form is greater at higher reaction temperatures and can be promoted by the transition-metal containing catalysts employed in the reduction step. The formation of furans may therefore be minimzed by the use of lower reaction temperatures and by designing the process such that once formed the diol is removed from the catalytic environment. The latter objective is met by the use of a continuous process whereby the reactants contact a high level of catalyst for a relatively short time and are then removed from the catalytic environment.
By optimization of the time of contact with the catalyst the formation of the desired diol is maximized and that of the furan by-product minimized.
It has also been found that the presence of acids promotes furan formation.
In particular, carboxylic acids which may be formed by certain ring-opening reactions of the cyclic anhydrides under the conditions of the reduction step can promote furan formation. This problem can be alleviated by first forming the lactone in a separate step as mentioned above or by the use of an additional esterification step in which the cyclic anhydride is first treated with an aicohol, particularly methanol, in the presence of an esterification catalyst to form a diester. The diester is then converted to the diol via the reduction step in accord with the invention.
O 97/28119 PCT~US97/00082 Optional alkoxvlation steP
The diol may optionaliy be alkoxylated prior to the sulfation step, such that alkoxylated disulfate cleaning agents are obtained as the final product.
Suitable methods for the alkoxylation of diols are described in US-A-3,832,408 and US-A-3,860,625. The condensation products of the diols with from 1 to 25 moles, preferably from 2 to 10 moles of alkylene oxide, particularly ethylene oxide andlor propylene oxide, are preferred herein.
Sulfation step The sulfation step may be carried out using any of the sulfation steps known in the art, including for example those described in US-A-3,634,269, US-A-3,9~9,334 and US-A ~,000,081. In particular the sulfation may be carried out in two stages where the first stage involves treatment of the diol with a suifation agent, generally selected from the group consisting of chlorosulfonic acid, sulfur trioxide, adducts of sulfur trioxide with amines andany mixtures thereof. The second stage involves neutralization, which is generally carried out using NaOH.
Example Set 1- Synthesis of t::14 alkvl-1~4-disulfate Cyclic anhvdride startinq ma~e, ial Decyl succinic anhydride as shown in the reaction scheme below (R = a heptyl group) was employed as the starting material. This material was obtained by hydrogenation in the presence of a Pd catalyst of the alkenyl succinic anhydride product obtained from the 'ene' reaction of maleic (acid) anhydride with dec-1-ene.
W O 97/28119 PCTrUS97/00082 Reaction scheme - reduction steP
The general reaction scheme for the reduction step is as outlined below:
.
//
R ~ Cu Chromite (cat) R=C7 l /~
. . ~~ Alcohol solvent R'OH
Alkylsucc~nlc \\
Anhydride O
R~OH R
Alkyl 1,4-Diol l~ OH Alkylfuran _ ~~
R / ~ , CO2R' I
Hal~-ester It should be noted from the above that both furan and half ester by-products can also be formed in the reaction.
Process details The reactor utilized was an electrically heated 500 ml (39 mm internal diameter x 432 mm internal length) Autoclave Engineers type 316 (tradename) stainless steel rocking autoclave fitted with an internal thermocouple and valving for periodic sampling of reaction mixtures.
The reactor was charged with 50 ml of alcohol solvent and 5 grams of copper chromite catalyst, as sold by Engelhardt under the tradename CU-1885P, that had been washed several times with high purity water then several times with alcohol solvent. The reactor and contents were then CA 02244082 l998-07-23 PCT~US97/00082 ~0 heated to 250~C at a hydrogen pressure of 2.4 x 1 o6 Pa and held for 1 hour.
The reactor was then c0012d and charged (without exposing the catalyst to air) with 20 grams of the cyclic anhydride starting material and an additional 50 ml of alcohol solvent. The process was carried out under different conditions of pressure and temperature, and with varying reaction times.
Details of the different reaction conditions and of the yields obtained are summarized in the table below:
Example Pressure Temp. Time Solvent 1, 4 Furan Otherby-No. (106Pa) (~C) diol Yield product Yield 1 2.8 235 2.1 hr 1-butanol 74 9 17 2 2.1 210 48 hr 1-butanol 61 15 24 3 2.85 250 2.5 hr 1-butanol 62 9 26 4 2.1 250 15 hr methanol 24 41 35 2.1 300 15 hr methanol 0 76 24 6 2.1 200 15 hr 1-octanol ~5 7 2.1 192 4.5days isobutanol 52 33 15 8 2.1 187 2.5days ethylene <5 86 glycol AnalYtical method details Samples of the product from the reduction step were periodically taken. To determine the yield of 1,4 alkyl diol product and of the by-products, as given above, these samples were analyzed by Capillary Gas Chromatography, as now described:
The samples were filtered and then injected (280~C injection temperature and 100:1 split ratio~ into a HP 5880 (tradename) GC utilizing a FID detector (detector at 320~C~ and a J&W Scientific (tradename) DB-1 column ~15 metres x 0.257 mm internal diameter; 0.25 film thickness). The following temperature program was utilized: 170~C initial temperature with no hold period; increasing to 1 80~C at a 1 ~C/minute ramp; no hold period;
increasing to 320 ~C at 10 ~Clminute ramp.
CA 022440X2 l998-07-23 W O 97/28119 PCT~US97/00082 Sulfation step The sulfation step was carried out, in each case, on the 1,4-alkyl diolproduct obtained from the reduction step. Chlorosulfonic acid was used which resulted in a high yield (typically > 90%) of the required C14 alkyl 1,4 disulfate end-product as shown below:
R ~" l" OS03Na OS03Na R2 = H R = C7 ~
ExamPle Set ll - Svnthesis of C14 alkvl-1,4-disulfate The alkenyl succinic anhydride product obtained from the 'ene' reaction of maleic (acid) anhydride with dec-1-ene (i.e. R = a heptyl group) is used directly as the cyclic anhydride starting material. The need for the additional 'pre-step' of reduction of the alkenyl succinic anhydride to an alkyl succinic anhydride is thus avoided. All other method steps are as in Example Set 1.
The reaction scheme for the reduction step is thus as shown below:
CA 02244082 l998-07-23 W O 97/28119 PCT~US97/00082 R \ CopperChromite, H2 O
~ Butanol Solvent Alkenylsuccinic \\
Anhydride O OButyl R~\OH ~ ~
Alkyl-1,4-Diol ~OH Half esters ~ ~
R ~\ OH
Alkylfuran ~~
ExamPle Set lll - Svnthesis of C14 alkyl-1~4-ethoxvlate disulfate The method steps of Example Set I are followed to give the 1,4 alkyl diol.
This is then treated with an excess of ethylene oxide to give the ethoxylated diol. The sulfation step of Example Set I is then repeated to give a C14 alkyl-1,4-ethoxylate disulfate end-product.
Backqround to the invention Specific use of dianionic surfactants, that is surfactants having two anionically charged groups, as detergent components has been previo~sly described. Disulfated surfactants, in particular 1,4 disulfated surfactants and alkoxylated forms thereof, are specific examples of such dianionic surfactants.
Disulfated surfactants have not to date found common use in the detergent industry because of the difficulty ~ssoci~ted in deriving a commercially viable route for their bulk preparation. Commercial viability is, in general terms, dictated by the need to employ inexpensive, readily available starting materials capable of translation into 'end product' via a synthetic route which is energy efficient, employs inexpensive, readily available reagents and provides high yields.
Known syntheses of disulfated surfactants, in general, use an alkyl or alkenyi succinic anhydride as the principal starting material. This is initiallysubjected to a reduction step from which a diol is obtained. Subse~uently the diol is su~ected to a sulfation step to give the disulfated product.
Optionally, an alkoxylation step may be introduced prior to the sulfation step such that alkoxylated disulfate cleaning agents are obtained.
As an example, US-A-3,634,269 describes phosphate-free detergent compositions containing 2-alkyl or alkenyl-1,4-butanediol disulfates.
Described therein, is their preparation by the reduction of alkenyl succinic anhydrides with lithium aluminium hydride to produce either alkenyl or alkyl diols which are then sulfated.
CA 02244082 l998-07-23 W O 97/28119 PCTnUS97/00082 Additionally, US-A-3,9~9,334 and US-A4,Q00,081 describe 2-hydrocarbyl-1,4-butanediol disulfates said to be suitable as lime soap dispersants Again, the method for synthesizing these disulfates involves the reduction of alkenyl succinic anhydrides with lithium aluminium hydride to produce either alkenyl or alkyl diols which are then sulfated.
US-A-3,832,408 and US-A-3,860,625 describe phosphate-free detergent compositions containing 2-alkyl or alkenyl-1,4-butanediol ethoxylate disulfates. Their preparation by the reduction of alkenyl succinic anhydrides with lithium aluminium hydride to produce either alkenyl or alkyl diols which are then ethoxylated prior to sulfation is described.
A problem associated with the known synthetic routes to 1,4 disulfated surfactants is that the reduction step involves the use of pyrophoric and expensive lithium aluminum hydride (LiAlH4) to reduce the anhydride to the 1,4-diol. Safe handling of pyrophoric ~l~alerials requires special process equipment which further adds to processing complexity and cost.
Additionally, aluminium salts which are formed in the process require special care in their dispossl.
The Applicants have now found an alternative method of carrying out thereduction step involving hydrogenation of the anhydride in the presence of a transition metal-containing hydrogenation catalyst. Thus use of lithium aluminium hydride, and the potential problems related thereto, may be avoided.
Summarv of the Invention According to the present invention there is provided a method of synthesis of a disulfated cleaning agent from a substituted cyclic anhydride having one or more carbon chain substituents comprising in total at least 5 carbon atoms comprising the following steps:
(i) reduction of said substituted cyclic anhydride to form a diol;
W O 97/28119 PCTrUS97/00082 (ii) optionally, alkoxylation of said diol to form an alkoxylated diol; and ~iii) sulfation of said diol or alkoxylated diol to form a disulfate wherein said reduction step comprises hydrogenation under pressure in the presence of a transition metai-containing hydrogenation catalyst.
[)etailed description of the invention There is provided a method for the synthesis of a disulfated cleaning agent from a substituted cyclic anhydride.
Cvclic anhvdride startin~ material The cyclic anhydride starting material has a ring structure and comprises an acid anhydride linkage. Cyclic anhydrides are generally formed by a ring forming condensation reaction of a single organic compound having a first carboxylic acid (-COOH) functional group and a second -COY functional group separated from the carboxylic acid functional group by at least two carbon atoms, wherein Y is usually an -OH, or halogen functionality.
A specific example of an organic compound which may be condensed to form a cyclic anhydride is maleic acid which on self-condensation provides maleic anhydride. Maleic anhydride is readily available commercially.
The ring structure of the cyclic anhydride starting material contains from 4 to 7 carbon atoms, preferably from 4 to 6 carbon atoms in the ring structure.
Most pr~rerably the cyclic anhydride starting material is based on succinic anhydride which has a 5-membered ring structure containing 4 carbon atoms in the ring.
The cyclic anhydride starting material is substituted by one or more carbon containing substituents, such that in total, these substitutents contain at least S carbon atoms, preferably from S to 25 carbon atoms, more preferably from 7 to 21 carbon atoms.
CA 02244082 l998-07-23 W O 97/28119 PCTrUS97/00082 In a preferred aspect all of the carbon chain substituent(s) comprise either alkyl or alkenyl chains, which may be branched or unbranched. In one preferred aspect they are essentially unbranched. In another preferred aspect the chains are primarily monobranched, that is more than 50% by weight of the chains are monobranched.
In one preferred aspect the substituted cyclic anhydride has a single carbon chain substituent. In another preferred aspect the substituted cyclic anhydride has two carbon chain substituents each having different points of attachment to the ring structure.
Substituted alkenylsuccinic and alkylsuccinic anhydrides are suitable starting materials herein. Preferred anhydrides of this type have the following structures:
R~ O R2 o R ~' ' \ R /\\~
Alkylsuccinic L ~ Alk~ny~succinic l ~
Anhydride ~~ Anhydride ~
O O
where R and R2 are either H or an alkyl group. In one preferred aspect R2 is H.
Linear alkenylsuccinic anhydrides may be obtained in high yield from the single stage 'ene reaction' of maleic anhydride with an alpha-olefin.
Branched alkenylsuccinic anhydrides may be obtained from the single stage 'ene reaction' of maleic anhydride with an internal olefin, such as those obtainable from the familiar SHOP ~tradename of the Shell Corporation) olefin making process. Preferably the substituted alkenylsuccinic or alkylsuccinic anhydride starting materials will be substantialiy pure and, in particular, dimeric impurities are preferably minimised. Thus, preferably the cyclic anhydride starting material contains less than 30% dimeric impurities, more preferably less than 10%, most preferably less than 5% or even less than 2.5 or 1% by weight. Such impurities can be minimised by conventional techniques within the limit of the skilled person, for example either by selection of appropriate reaction conditions in producing the cyclic anhydride starting material (such as low temperature) or by subsequent purification, for example by distillation.
Alkylsuccinic anhydride starting materials can be made by reducing alkenylsuccinic anhydrides. This reduction can be achieved under the conditions of the catalytic hydrogenation reduction step of the present invention.
The reduction steP
The first step of the synthetic method of the invention is the reduction of the substituted cyclic anhydride to form a diol. The reduction step comprises hydrogenation under pressure in the presence of a transition metal-containing hydrogenation catalyst.
It is an advantage of the present invention that under the conditions of the catalytic hydrogenation reduction step any alkene linkages are also reduced to alkyl linkages. Thus, if an alkenylsuccinic anhydride is used as the starting material it is reduced via a (single) reduction step to the diol havingalkyl chain substituents, as are desired. This contrasts with the situation where LiAlH4, which does not reduce alkene linkages, is used in the reduction step, wherein an extra step involving the reduction of the alkenyl succinic anhydride to the alkyl succinic anhydride (via e.g. Pd/hydrogen) must be employed to obtain the desired diol product.
~a) Hvdro~enation catalvst The hydrogenation catalyst acts functionally to enhance the efficiency of the reductive hydrogenation process. For use on a commercial scale it is desirable that the catalyst is easy to regenerate.
Preferably the catalyst contains a transition metal selected from the group consisting of the group VIA (particularly Cr), VIIA (particularly Mn), Vlll (particularly Fe, Co, Ni, Ru, Rh) and IB (particularly Cu) elements. Catalysts con~ai,ling mixtures of any of these transition metals are envisaged as are W O 97128119 PCT~US97/00082 catalysts containing other rnetais including the alkali and alkaline earth metals.
Copper-containing catalysts, particularly copper chromite (which is commercially available and relatively easy to regenerate~ are most ,urefe~, ed.
The hydrogenation catalyst may advantageously ~e supported on an inert support material. The support material generally comprises an oxide salt comprising a metal selected from the group consisting of aluminium, silicon and any mixtures thereof. Supports comprising aluminium oxide or silicon dioxide are especially preferred. Clay materials are also suitable supports.
~b) Process details The reductive hydrogenation step is carried out under pressure, and generally at elevated temperature. Usually a solvent is employed. This step can be carried out by a batch, continuous or vapor-phase process. A
continuous process is p,erer,~:d.
The pressure is typically from 1 x 105 to 1 x 107 Pa, more preferably from 1 x 1~6 to ~ x 106 Pa. The temperature is generally from 150 to 350~C, more preferabiy from 20t~ to 300~C. The time of reaction is generally from 30 minutes to 10 hours.
Suitable solvents include alcohols, particularly methanol, ethanol, propanol and butanol.
It is to appreciated that the exact process conditions used for any particular synthesis will be varied to achieve optimum results in accord with the usual process optimization steps which will be within the remit of the skilled person. In particular the process conditions will be adjusted to minimize the occurence of any competing side-reactions.
One possible problem derives from the incomplete reduction of the cyclic anhydride, such that lactones are formed. These are however, convertible to W O 97128119 PCTrUS97/~0082 diols by further catalytic hydrogenation. It may be advantageous to carry out the hydrogenation in two steps preferably as part of a continuous step-wise process, such that a lactone is formed in the first step followed by a second step in which the lactone is reduced to the diol. Conditions which favour lactone formation are high temperature (~300 ~C) and low pressures (~ 1 x 105 Pa). Any water formed during the hydrogenation will primarily be in the vapour phase, so that the anhydride is unlikely to be converted to a carboxylic acid which can inhibit the catalyst. The best conditions for diol formation from the lactone are lower temperatures (~220 ~C) and high pressures (~ 1 x 107 Pa), both of which conditions minimize the production of furan by-product.
Furans can be formed by a ring closure reaction of the diol product.
Generally any furan by-product should be present in an amount below ~% of the desired diol, preferably below 2%, most preferaL,ly below 1.5% or even below 1% by weight of the desired diol.
The tendency for such furans to form is greater at higher reaction temperatures and can be promoted by the transition-metal containing catalysts employed in the reduction step. The formation of furans may therefore be minimzed by the use of lower reaction temperatures and by designing the process such that once formed the diol is removed from the catalytic environment. The latter objective is met by the use of a continuous process whereby the reactants contact a high level of catalyst for a relatively short time and are then removed from the catalytic environment.
By optimization of the time of contact with the catalyst the formation of the desired diol is maximized and that of the furan by-product minimized.
It has also been found that the presence of acids promotes furan formation.
In particular, carboxylic acids which may be formed by certain ring-opening reactions of the cyclic anhydrides under the conditions of the reduction step can promote furan formation. This problem can be alleviated by first forming the lactone in a separate step as mentioned above or by the use of an additional esterification step in which the cyclic anhydride is first treated with an aicohol, particularly methanol, in the presence of an esterification catalyst to form a diester. The diester is then converted to the diol via the reduction step in accord with the invention.
O 97/28119 PCT~US97/00082 Optional alkoxvlation steP
The diol may optionaliy be alkoxylated prior to the sulfation step, such that alkoxylated disulfate cleaning agents are obtained as the final product.
Suitable methods for the alkoxylation of diols are described in US-A-3,832,408 and US-A-3,860,625. The condensation products of the diols with from 1 to 25 moles, preferably from 2 to 10 moles of alkylene oxide, particularly ethylene oxide andlor propylene oxide, are preferred herein.
Sulfation step The sulfation step may be carried out using any of the sulfation steps known in the art, including for example those described in US-A-3,634,269, US-A-3,9~9,334 and US-A ~,000,081. In particular the sulfation may be carried out in two stages where the first stage involves treatment of the diol with a suifation agent, generally selected from the group consisting of chlorosulfonic acid, sulfur trioxide, adducts of sulfur trioxide with amines andany mixtures thereof. The second stage involves neutralization, which is generally carried out using NaOH.
Example Set 1- Synthesis of t::14 alkvl-1~4-disulfate Cyclic anhvdride startinq ma~e, ial Decyl succinic anhydride as shown in the reaction scheme below (R = a heptyl group) was employed as the starting material. This material was obtained by hydrogenation in the presence of a Pd catalyst of the alkenyl succinic anhydride product obtained from the 'ene' reaction of maleic (acid) anhydride with dec-1-ene.
W O 97/28119 PCTrUS97/00082 Reaction scheme - reduction steP
The general reaction scheme for the reduction step is as outlined below:
.
//
R ~ Cu Chromite (cat) R=C7 l /~
. . ~~ Alcohol solvent R'OH
Alkylsucc~nlc \\
Anhydride O
R~OH R
Alkyl 1,4-Diol l~ OH Alkylfuran _ ~~
R / ~ , CO2R' I
Hal~-ester It should be noted from the above that both furan and half ester by-products can also be formed in the reaction.
Process details The reactor utilized was an electrically heated 500 ml (39 mm internal diameter x 432 mm internal length) Autoclave Engineers type 316 (tradename) stainless steel rocking autoclave fitted with an internal thermocouple and valving for periodic sampling of reaction mixtures.
The reactor was charged with 50 ml of alcohol solvent and 5 grams of copper chromite catalyst, as sold by Engelhardt under the tradename CU-1885P, that had been washed several times with high purity water then several times with alcohol solvent. The reactor and contents were then CA 02244082 l998-07-23 PCT~US97/00082 ~0 heated to 250~C at a hydrogen pressure of 2.4 x 1 o6 Pa and held for 1 hour.
The reactor was then c0012d and charged (without exposing the catalyst to air) with 20 grams of the cyclic anhydride starting material and an additional 50 ml of alcohol solvent. The process was carried out under different conditions of pressure and temperature, and with varying reaction times.
Details of the different reaction conditions and of the yields obtained are summarized in the table below:
Example Pressure Temp. Time Solvent 1, 4 Furan Otherby-No. (106Pa) (~C) diol Yield product Yield 1 2.8 235 2.1 hr 1-butanol 74 9 17 2 2.1 210 48 hr 1-butanol 61 15 24 3 2.85 250 2.5 hr 1-butanol 62 9 26 4 2.1 250 15 hr methanol 24 41 35 2.1 300 15 hr methanol 0 76 24 6 2.1 200 15 hr 1-octanol ~5 7 2.1 192 4.5days isobutanol 52 33 15 8 2.1 187 2.5days ethylene <5 86 glycol AnalYtical method details Samples of the product from the reduction step were periodically taken. To determine the yield of 1,4 alkyl diol product and of the by-products, as given above, these samples were analyzed by Capillary Gas Chromatography, as now described:
The samples were filtered and then injected (280~C injection temperature and 100:1 split ratio~ into a HP 5880 (tradename) GC utilizing a FID detector (detector at 320~C~ and a J&W Scientific (tradename) DB-1 column ~15 metres x 0.257 mm internal diameter; 0.25 film thickness). The following temperature program was utilized: 170~C initial temperature with no hold period; increasing to 1 80~C at a 1 ~C/minute ramp; no hold period;
increasing to 320 ~C at 10 ~Clminute ramp.
CA 022440X2 l998-07-23 W O 97/28119 PCT~US97/00082 Sulfation step The sulfation step was carried out, in each case, on the 1,4-alkyl diolproduct obtained from the reduction step. Chlorosulfonic acid was used which resulted in a high yield (typically > 90%) of the required C14 alkyl 1,4 disulfate end-product as shown below:
R ~" l" OS03Na OS03Na R2 = H R = C7 ~
ExamPle Set ll - Svnthesis of C14 alkvl-1,4-disulfate The alkenyl succinic anhydride product obtained from the 'ene' reaction of maleic (acid) anhydride with dec-1-ene (i.e. R = a heptyl group) is used directly as the cyclic anhydride starting material. The need for the additional 'pre-step' of reduction of the alkenyl succinic anhydride to an alkyl succinic anhydride is thus avoided. All other method steps are as in Example Set 1.
The reaction scheme for the reduction step is thus as shown below:
CA 02244082 l998-07-23 W O 97/28119 PCT~US97/00082 R \ CopperChromite, H2 O
~ Butanol Solvent Alkenylsuccinic \\
Anhydride O OButyl R~\OH ~ ~
Alkyl-1,4-Diol ~OH Half esters ~ ~
R ~\ OH
Alkylfuran ~~
ExamPle Set lll - Svnthesis of C14 alkyl-1~4-ethoxvlate disulfate The method steps of Example Set I are followed to give the 1,4 alkyl diol.
This is then treated with an excess of ethylene oxide to give the ethoxylated diol. The sulfation step of Example Set I is then repeated to give a C14 alkyl-1,4-ethoxylate disulfate end-product.
Claims (21)
1. A method of synthesis of a disulfated cleaning agent from a substituted cyclic anhydride having one or more carbon chain substituents comprising in total at least 5 carbon atoms comprising the following steps:
(i) reduction of said substituted cyclicanhydride to form a diol;
(ii) optionally, alkoxylation of said diol to form an alkoxylated diol; and (iii) sulfation of said diol or alkoxylated diol to form a disulfate wherein said reduction step comprises hydrogenation under pressure in the presence of a transition metal-containing hydrogenation catalyst.
(i) reduction of said substituted cyclicanhydride to form a diol;
(ii) optionally, alkoxylation of said diol to form an alkoxylated diol; and (iii) sulfation of said diol or alkoxylated diol to form a disulfate wherein said reduction step comprises hydrogenation under pressure in the presence of a transition metal-containing hydrogenation catalyst.
2. A method according to Claim 1 wherein the substituted cyclic anhydride contains from 4 to 7 carbon atoms in the ring structure.
3. A method according to Claim 2 wherein the substituted cyclic anhydride is a substituted succinic anhydride.
4. A method according to any of Claims 1 to 3 wherein the substituted cyclic anhydride has a single carbon chain substituent.
5. A method according to any of Claims 1 to 3 wherein the substituted cyclic anhydride has two carbon chain substituents each having different points of attachment to the ring structure.
6. A method according to any of Claims 1 to 5 wherein the carbon chain substituent(s) comprise either alkyl or alkenyl chains.
7. A method according to Claim 6 wherein said alkyl or alkenyl chains are essentially unbranched.
8. A method according to Claim 6 wherein said alkyl or alkenyl chains are primarily monobranched.
9. A method according to any of Claims 1 to 8 wherein the carbon chain substituent(s) comprise in total from 5 to 25 carbon atoms, preferably from 7 to 21 carbon atoms.
10. A method according to any of Claims 1 to 9 wherein said hydrogenation catalyst contains a transition metal selected from the group consisting of the group VIA, VIIA, VIII and IB elements, and any mixtures thereof.
11. A method according to Claim 10 wherein said hydrogenation catalyst contains copper.
12. A method according to Claim 11 wherein said hydrogenation catalyst is copper chrontite.
13. A method according to any of Claims 1 to 12 wherein said hydrogenation catalyst is supported by an inert support material.
14. A method according to Claim 13 wherein said support material is an oxide salt comprising a metal selected from the group consisting of aluminium, silicon and any mixtures thereof.
15. A method according to any of Claims 1 to 14 additionally having an esterification step in which the substituted cyclic anhydride is treated with analcohol, particularly methanol, in the presence of an esterification catalyst toform a diester, which is then reduced by said reduction step to a diol.
16. A method according to any of Claims 1 to 15 wherein said reduction step is carried out in the presence of a solvent, preferably an alcohol.
17. A method according to any of Claims 1 to 16 wherein said reduction step is carried out at a pressure of from 1 x 10 6 to 1 x 10 7 Pa.
18. A method according to any of Claims 1 to 17 wherein said reduction step is carried out at a temperature of from 150 to 350°C.
19. A method according to any of Claims 1 to 18 wherein said reduction step is carried out by a continuous process.
20. A method according to any of Claims 1 to 19 wherein said sulfation step is carried out using a sulfation agent selected from the group consisting of chlorosulfonic acid, sulfur trioxide, adducts of sulfur trioxide with amines andany mixtures thereof.
21. Disulfated cleaning agent product obtainable by a method according to any of Claims 1 to 20.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9601880A GB2310206A (en) | 1996-01-31 | 1996-01-31 | Disulfated cleaning agent synthesis |
| GB9601880.9 | 1996-01-31 | ||
| PCT/US1997/000082 WO1997028119A1 (en) | 1996-01-31 | 1997-01-06 | Synthesis of anionic cleaning agents |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2244082A1 true CA2244082A1 (en) | 1997-08-07 |
Family
ID=29422163
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2244082 Abandoned CA2244082A1 (en) | 1996-01-31 | 1997-01-06 | Synthesis of anionic cleaning agents |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2244082A1 (en) |
-
1997
- 1997-01-06 CA CA 2244082 patent/CA2244082A1/en not_active Abandoned
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