CA1121384A - Method for the preparation of vanillin - Google Patents
Method for the preparation of vanillinInfo
- Publication number
- CA1121384A CA1121384A CA000341137A CA341137A CA1121384A CA 1121384 A CA1121384 A CA 1121384A CA 000341137 A CA000341137 A CA 000341137A CA 341137 A CA341137 A CA 341137A CA 1121384 A CA1121384 A CA 1121384A
- Authority
- CA
- Canada
- Prior art keywords
- vanillin
- alcohol
- organic solvent
- solvent
- bisulphite
- 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.)
- Expired
Links
- MWOOGOJBHIARFG-UHFFFAOYSA-N vanillin Chemical compound COC1=CC(C=O)=CC=C1O MWOOGOJBHIARFG-UHFFFAOYSA-N 0.000 title claims abstract description 64
- FGQOOHJZONJGDT-UHFFFAOYSA-N vanillin Natural products COC1=CC(O)=CC(C=O)=C1 FGQOOHJZONJGDT-UHFFFAOYSA-N 0.000 title claims abstract description 64
- 235000012141 vanillin Nutrition 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims abstract description 14
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000000605 extraction Methods 0.000 claims abstract description 12
- 239000003960 organic solvent Substances 0.000 claims abstract description 11
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 9
- 239000000243 solution Substances 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000004117 Lignosulphonate Substances 0.000 claims abstract description 7
- 235000019357 lignosulphonate Nutrition 0.000 claims abstract description 7
- 239000002994 raw material Substances 0.000 claims abstract description 6
- 229920001732 Lignosulfonate Polymers 0.000 claims abstract description 5
- 230000003647 oxidation Effects 0.000 claims abstract description 5
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 5
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 claims abstract description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 27
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 18
- 239000012535 impurity Substances 0.000 claims description 16
- 238000001704 evaporation Methods 0.000 claims description 10
- 239000002904 solvent Substances 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 230000008020 evaporation Effects 0.000 claims description 6
- 159000000000 sodium salts Chemical class 0.000 claims description 6
- 238000000926 separation method Methods 0.000 claims description 5
- 239000000284 extract Substances 0.000 claims description 4
- 238000000108 ultra-filtration Methods 0.000 claims description 4
- 239000003513 alkali Substances 0.000 claims description 3
- 239000002699 waste material Substances 0.000 claims description 3
- 238000009835 boiling Methods 0.000 claims description 2
- 239000001913 cellulose Substances 0.000 claims description 2
- 229920002678 cellulose Polymers 0.000 claims description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims 2
- 239000000203 mixture Substances 0.000 claims 2
- 239000011541 reaction mixture Substances 0.000 claims 2
- 238000006243 chemical reaction Methods 0.000 claims 1
- ZSIAUFGUXNUGDI-UHFFFAOYSA-N hexan-1-ol Chemical compound CCCCCCO ZSIAUFGUXNUGDI-UHFFFAOYSA-N 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 239000012528 membrane Substances 0.000 claims 1
- 230000001590 oxidative effect Effects 0.000 claims 1
- 230000003134 recirculating effect Effects 0.000 claims 1
- 229910000029 sodium carbonate Inorganic materials 0.000 claims 1
- 238000005406 washing Methods 0.000 claims 1
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 abstract description 10
- 235000010269 sulphur dioxide Nutrition 0.000 abstract description 5
- 239000004291 sulphur dioxide Substances 0.000 abstract description 5
- 238000004537 pulping Methods 0.000 abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 7
- 239000000126 substance Substances 0.000 description 6
- 229920005610 lignin Polymers 0.000 description 5
- RGHHSNMVTDWUBI-UHFFFAOYSA-N 4-hydroxybenzaldehyde Chemical compound OC1=CC=C(C=O)C=C1 RGHHSNMVTDWUBI-UHFFFAOYSA-N 0.000 description 4
- PZSJOBKRSVRODF-UHFFFAOYSA-N vanillin acetate Chemical compound COC1=CC(C=O)=CC=C1OC(C)=O PZSJOBKRSVRODF-UHFFFAOYSA-N 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 150000001299 aldehydes Chemical class 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 150000003839 salts Chemical group 0.000 description 3
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 2
- -1 acetovanillin Chemical compound 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000008346 aqueous phase Substances 0.000 description 2
- 239000002021 butanolic extract Substances 0.000 description 2
- LHGVFZTZFXWLCP-UHFFFAOYSA-N guaiacol Chemical compound COC1=CC=CC=C1O LHGVFZTZFXWLCP-UHFFFAOYSA-N 0.000 description 2
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 2
- 239000004289 sodium hydrogen sulphite Substances 0.000 description 2
- 239000012485 toluene extract Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 241000218657 Picea Species 0.000 description 1
- 241000022563 Rema Species 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- DFYRUELUNQRZTB-UHFFFAOYSA-N apocynin Chemical compound COC1=CC(C(C)=O)=CC=C1O DFYRUELUNQRZTB-UHFFFAOYSA-N 0.000 description 1
- 239000003849 aromatic solvent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-M bisulphate group Chemical group S([O-])(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000004587 chromatography analysis Methods 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 229960001867 guaiacol Drugs 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- JJVNINGBHGBWJH-UHFFFAOYSA-N ortho-vanillin Chemical compound COC1=CC=CC(C=O)=C1O JJVNINGBHGBWJH-UHFFFAOYSA-N 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000005185 salting out Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- ZFRVFUWCVYLUIH-UHFFFAOYSA-M sodium vanillate Chemical compound [Na+].COC1=CC(C([O-])=O)=CC=C1O ZFRVFUWCVYLUIH-UHFFFAOYSA-M 0.000 description 1
- 239000011122 softwood Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 239000011269 tar Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Abstract
Abstract of the Disclosure A method for the preparation of vanillin from lignosulphonate is disclosed herein. The lignosulphonate used as raw material is ob-tained in connection with sulphite pulping. For the preparation of vanillin only such a portion of said lignosulphonate is used the molecular weight of which exceeds by more than 50 per cent the value 5000. The vanillin is prepared from said raw material in a manner known per se by oxidation and alcohol extractions. The vanillin ob-tained is then reacted with sulphur dioxide in order to give the bisulphite complex of vanillin. The bisulphite complex formed is decomposed by adding an alakali and extracted during the decomposi-tion or immediately thereupon with an organic solvent. The solu-tion is washed with slighty alkaline water and the organic solvent is thereafter evaporated in a low vacuum to get crude vanillin.
Description
~L~Z~ ~38~
At present vanillin is prepared mainly by alkaline oxidation of lignin obtained from sulphite cellulose pulping~of softwood. In a typical vanillin process, oxidized pulping waste liquor is extracted, for example, by means of a watersoluble alcohol (Sandborn, Finnish Patent No. 20,078 of the year 19LI4) in which process vanillin as well as all other low-molecular substances that form sodium salts are dissolved in salt form in the alcohol phase. The dissolution takes place mainly due to the very high salt and alkali concentrations of the oxidized aqueous phase causing a so-called salting out effect.
In another known method the oxidized liquor is neutralized to free vanillin from its salt and extracted with an organic solvent under conditions where pH is less than 7. The organic solvent used can be benzene, xylene, or an aliphatic solvent. This procedure is des-cribed, for example, in Finnish Patent No. 17,966 of 1936.
In all known methods for the preparation of vanillin, after having brought vanillin together with its typical impurities into a solu-tion, the next step is to separate vanillin from said impurities.
Most of the separation methods are of the type where vanillin as the main component is converted into a purer form. These separà~ion steps mainly comprise physical separations and bisulphite complexation separating aldehydes-from the other chemicals. The physical separa-tion operations are often dissatisfactory for two reasons: They separate vanillin and the impurity unsharply. They involve a recir-culation of large quantities of vanillin in the process and, conse-quently, as impurities continue to accumulate, call for more and.more separation. On the other hand, if the recircul-ation of vanillin is to be avoided, big losses of van;llin will inevitably be encountered.
, The process for the preparation of vanillin can be simplified, if the amount of impurities can be reduced at the very beginning. It is obvious that if the starting material is a raw material with a higher than normal content of lignosulphonate, the oxidized liquor will also have a higher than normal content of vanillin. The oxidation me~I-ods will not be discussed here because they have been described in a number of patent and other publications.
, 3~3~
Surprisingly, the Applicants haYe now found t'nat the impurity occurring in the highest content in vanillin, i.e. acetovanillin, is formed during oxidation mainly from low-molecular weight ligninc. By remov-ing from the liquor to be oxidized the low-molecular weight lignins before o~idation, the quantity of acetovanillin will be reduced by two thirds as compared witl- the conventional process. This advantase leads to other improvements to be described later and simplifies the process for the preparation of vanillin.
In the processes for the preparation of vanillin in which vanillirl is extracted with an alcohol, vanillin will contain, in addition to the typical impurities acetovanillin, parahydroxy benzaldehyde, quaiacol, vanillin acid, o-vanillin, a large quantity of low-molecu-lar weight partly desulphonated lignin.
Vanillin can, of course, be removed from alcohol in a number of different ways, for example, by evaporation or extraction in the form of a sodium salt, or by extraction as free vanillin. If vanillin is extracted from alcohol as a sodium salt, it can be conveniently processed further so as to form the bisulphite complex of vanillin by utilizing sulphur dioxide. Frorn this bisulphite complex non-alde-hydic non-complex impurities as well as the partly desulphonized lignins, thereafter called "tars", can be readily extracted. The relatively pure bisulphate complex of vanillin so obtained must be decomposed, said decomposition most often being carried out by using sulphuric acid whereby sulphur dioxide will be freed. However, in such a decomposition a fairly large portion of vanillin is destroyed as it is polymerized partly with itself, partly with the impurities.
.
It is known to decompose the bisulphite complex of aldehydes also by using alkalis whereby bisulphite is converted into sulphite. Further, it is known to extract aldehydes directly from such a complex solu-tion with a solvent at a raised temperature.
The Applicants have found that the best method is to combine the two methods described above, for freeing vanillin, ~hat is a simul-taneously decompozing with an alkali and extracting with an organic 38~
solvent. When sodium ca!bonate is used for the decomposition, the final pH value in the decomposition will be 7.9 ~Ihich ln extensive experiments has proved to be the bes~ p~l value also for the extrac-tion.
When operating at said pH level, all tarry impurities will rema;n in the alkaline aqueous phase, and only aldehydes will be transferred to the organic solvent. The best organic solvents to be used here are aromatic solvents, above all toluene. From the obtained vanillin/
toluene solution the aldyhydes, above all p-hydroxy benzaldehyde having a more acid charactcr than vanillin can now be very advanta-geously extracted. This is best done by using slightly alkaline water The final purification is best carried out by evaporating the toluene while using for the evaporation a maximum temperature of 130C and a pressure of about 5 kPa. Such an evaporation can be carried out in any apparatus, but is best done in a thin film evaporator provided with several separate heating zones. The evaporation is carried out at constant pressure while the temperature increases toward the bottom of the apparatus from about 60C to 130C. The evaporation will subsequently be continued in a second similar apparatus nearly at the same temperature, but now at an essentially lower pressure of 0.2 kPa. In this apparatus, vanillin is vapourized from high-molecu-lar impurities and from impurities with a higher boiling point. In ehe manner described, a very pure crude vani!lin is produced, the purity being more than g9.5 per cent.
The enclosed s~n~le ~igure represe~ts in the form of a flowsheet an ~rr~bodimen~ o~ the invention which is further illustrated by the following example.
Example . 4525 kg of oxidized sodium bisulphite waste liquor originally purified by ultrafiltration and obtained from Finnish spruce and containing 1.53 per cent by weight of vanillin having a density of 1.22 was continuously extracted with butanol.
The butanol extraction was carried out at a temperature of 53C using n-butanol saturated with water and having a density of 0.8~3. The raffinate obtained by the extraction contained 0.002 per cent of vanillin. The extract obtained contained l.48 per cent by weiyht of vanillin. In addition, the extract contained l.0l per cent by weight of other dissolved organic substances, such as vanillin. The butanol extract was re-extracted with water containing 0.2 per cent by weight of NaOH. The purpose of this was to prevent harmful forma-tion of an emulsion in the extraction. The aqueous raffinate ob-tained contained now 2.R8 per cent by weight of vanillin and the butanol extract 0.03 per cent of vanillin. The same butanol was used six times to extract vanillin from the oxidized raw material.
No difference was noted in the butanol after the first and sixth extraction.
The wa~er phase containing the sodium salt of vanillin, thus obtained and amounting to 2.370 kg in total, was evaporated in a vacuum evapo-rator at a temperature of 35C to 1~53 kg. The evaporated product con-tained about l50 g/kg of vanillin while the total dry substance con-tent was more than 300 g/kg.
.
The concentrated aqueous solution of sodium vanillate was treated with gaseous sulphur dioxide in a reactor provided with a mixer whereby the sodium bisulphite complex of vanillin was formed in a manner known per se. Gaseous sulphur dioxide was fed to the reactor until the pH was decreased to 4.5. The aqueous solution of the bi-sulphite complex became lighter in colour and tarry substances began to separate from it. Said solution was fed into an extraction column in which it was counter-current treated with n-butanol at a tempèra-ture of 25C. Non-aldehydic impurities were extracted from the aqueous solution with butanol, as well as the tarry substances.
The bisulphite complex so purified was clear and light in colour.
The n-butanol used in the extraction contained, for example, 30 9/1 of quaiacol, 35 9/1 of acetovanillin and 5 9/1 vanillin as well as about l40 g/l of other, mainly tarry, desulphonated lignins.
he purified bisulphite complex of vanillin was decomposed by aclding NaOH until the pH was 7.9.
3~ -The aqueous solution so obtained was heated to a temperature of 65C
and continuously extracted with toluene to obtain a clear yellowish toluene extract. Said extract contained 81 9/1 of vanillin while tl-e bottom product contained 24 ~/1 of vanillin.
The toluene extract obtained was washed twice with a small quar,tity of pure water so as to remove the remnants of sodium salts and any heavy phase possibly transferred during extraction. In the toluene solution so obtained the purity of vanillin was more than 98 per cent.
The toluene solution was evaporated while a small quantity of guaiacol was also evaporated along with the toluene.
The solid brown-yellow crude vanillin having a melting point of 79.5C
was distilled in vacuum at a temperature of 140C and at a pressure Oc 1 to 2 mm Hg. In the distillation, the entire distillate was recovered while the amount of the bottom product remained was about 5 per cent of the feed. The bottom product was entirely dissolved in the lye solu-tion and can be recirculated to the process. The distillate had a light yellow colour and a melting point of 80C. The distillate ob-tained was dissolved in water to form a 5 per cent solution, filtered througl- active carbon whereby the yellowish colour disappeared, and crystallized from water in the conventional manner by cooling to 5C.
The crystals were separated by filtering, and dried a-t a temperature of 60C and at a presuure of 4 to 5 mm Hg for four hours. The melting point of the crystals obtained was 81.4 to 82.2 C. The gas chromato-graphic analysis gave 0.05 per cent of acetOvanillon and 0.05 per cent of orthovanillon as impurities in the crystals. No traces of other impurities were found.
.
At present vanillin is prepared mainly by alkaline oxidation of lignin obtained from sulphite cellulose pulping~of softwood. In a typical vanillin process, oxidized pulping waste liquor is extracted, for example, by means of a watersoluble alcohol (Sandborn, Finnish Patent No. 20,078 of the year 19LI4) in which process vanillin as well as all other low-molecular substances that form sodium salts are dissolved in salt form in the alcohol phase. The dissolution takes place mainly due to the very high salt and alkali concentrations of the oxidized aqueous phase causing a so-called salting out effect.
In another known method the oxidized liquor is neutralized to free vanillin from its salt and extracted with an organic solvent under conditions where pH is less than 7. The organic solvent used can be benzene, xylene, or an aliphatic solvent. This procedure is des-cribed, for example, in Finnish Patent No. 17,966 of 1936.
In all known methods for the preparation of vanillin, after having brought vanillin together with its typical impurities into a solu-tion, the next step is to separate vanillin from said impurities.
Most of the separation methods are of the type where vanillin as the main component is converted into a purer form. These separà~ion steps mainly comprise physical separations and bisulphite complexation separating aldehydes-from the other chemicals. The physical separa-tion operations are often dissatisfactory for two reasons: They separate vanillin and the impurity unsharply. They involve a recir-culation of large quantities of vanillin in the process and, conse-quently, as impurities continue to accumulate, call for more and.more separation. On the other hand, if the recircul-ation of vanillin is to be avoided, big losses of van;llin will inevitably be encountered.
, The process for the preparation of vanillin can be simplified, if the amount of impurities can be reduced at the very beginning. It is obvious that if the starting material is a raw material with a higher than normal content of lignosulphonate, the oxidized liquor will also have a higher than normal content of vanillin. The oxidation me~I-ods will not be discussed here because they have been described in a number of patent and other publications.
, 3~3~
Surprisingly, the Applicants haYe now found t'nat the impurity occurring in the highest content in vanillin, i.e. acetovanillin, is formed during oxidation mainly from low-molecular weight ligninc. By remov-ing from the liquor to be oxidized the low-molecular weight lignins before o~idation, the quantity of acetovanillin will be reduced by two thirds as compared witl- the conventional process. This advantase leads to other improvements to be described later and simplifies the process for the preparation of vanillin.
In the processes for the preparation of vanillin in which vanillirl is extracted with an alcohol, vanillin will contain, in addition to the typical impurities acetovanillin, parahydroxy benzaldehyde, quaiacol, vanillin acid, o-vanillin, a large quantity of low-molecu-lar weight partly desulphonated lignin.
Vanillin can, of course, be removed from alcohol in a number of different ways, for example, by evaporation or extraction in the form of a sodium salt, or by extraction as free vanillin. If vanillin is extracted from alcohol as a sodium salt, it can be conveniently processed further so as to form the bisulphite complex of vanillin by utilizing sulphur dioxide. Frorn this bisulphite complex non-alde-hydic non-complex impurities as well as the partly desulphonized lignins, thereafter called "tars", can be readily extracted. The relatively pure bisulphate complex of vanillin so obtained must be decomposed, said decomposition most often being carried out by using sulphuric acid whereby sulphur dioxide will be freed. However, in such a decomposition a fairly large portion of vanillin is destroyed as it is polymerized partly with itself, partly with the impurities.
.
It is known to decompose the bisulphite complex of aldehydes also by using alkalis whereby bisulphite is converted into sulphite. Further, it is known to extract aldehydes directly from such a complex solu-tion with a solvent at a raised temperature.
The Applicants have found that the best method is to combine the two methods described above, for freeing vanillin, ~hat is a simul-taneously decompozing with an alkali and extracting with an organic 38~
solvent. When sodium ca!bonate is used for the decomposition, the final pH value in the decomposition will be 7.9 ~Ihich ln extensive experiments has proved to be the bes~ p~l value also for the extrac-tion.
When operating at said pH level, all tarry impurities will rema;n in the alkaline aqueous phase, and only aldehydes will be transferred to the organic solvent. The best organic solvents to be used here are aromatic solvents, above all toluene. From the obtained vanillin/
toluene solution the aldyhydes, above all p-hydroxy benzaldehyde having a more acid charactcr than vanillin can now be very advanta-geously extracted. This is best done by using slightly alkaline water The final purification is best carried out by evaporating the toluene while using for the evaporation a maximum temperature of 130C and a pressure of about 5 kPa. Such an evaporation can be carried out in any apparatus, but is best done in a thin film evaporator provided with several separate heating zones. The evaporation is carried out at constant pressure while the temperature increases toward the bottom of the apparatus from about 60C to 130C. The evaporation will subsequently be continued in a second similar apparatus nearly at the same temperature, but now at an essentially lower pressure of 0.2 kPa. In this apparatus, vanillin is vapourized from high-molecu-lar impurities and from impurities with a higher boiling point. In ehe manner described, a very pure crude vani!lin is produced, the purity being more than g9.5 per cent.
The enclosed s~n~le ~igure represe~ts in the form of a flowsheet an ~rr~bodimen~ o~ the invention which is further illustrated by the following example.
Example . 4525 kg of oxidized sodium bisulphite waste liquor originally purified by ultrafiltration and obtained from Finnish spruce and containing 1.53 per cent by weight of vanillin having a density of 1.22 was continuously extracted with butanol.
The butanol extraction was carried out at a temperature of 53C using n-butanol saturated with water and having a density of 0.8~3. The raffinate obtained by the extraction contained 0.002 per cent of vanillin. The extract obtained contained l.48 per cent by weiyht of vanillin. In addition, the extract contained l.0l per cent by weight of other dissolved organic substances, such as vanillin. The butanol extract was re-extracted with water containing 0.2 per cent by weight of NaOH. The purpose of this was to prevent harmful forma-tion of an emulsion in the extraction. The aqueous raffinate ob-tained contained now 2.R8 per cent by weight of vanillin and the butanol extract 0.03 per cent of vanillin. The same butanol was used six times to extract vanillin from the oxidized raw material.
No difference was noted in the butanol after the first and sixth extraction.
The wa~er phase containing the sodium salt of vanillin, thus obtained and amounting to 2.370 kg in total, was evaporated in a vacuum evapo-rator at a temperature of 35C to 1~53 kg. The evaporated product con-tained about l50 g/kg of vanillin while the total dry substance con-tent was more than 300 g/kg.
.
The concentrated aqueous solution of sodium vanillate was treated with gaseous sulphur dioxide in a reactor provided with a mixer whereby the sodium bisulphite complex of vanillin was formed in a manner known per se. Gaseous sulphur dioxide was fed to the reactor until the pH was decreased to 4.5. The aqueous solution of the bi-sulphite complex became lighter in colour and tarry substances began to separate from it. Said solution was fed into an extraction column in which it was counter-current treated with n-butanol at a tempèra-ture of 25C. Non-aldehydic impurities were extracted from the aqueous solution with butanol, as well as the tarry substances.
The bisulphite complex so purified was clear and light in colour.
The n-butanol used in the extraction contained, for example, 30 9/1 of quaiacol, 35 9/1 of acetovanillin and 5 9/1 vanillin as well as about l40 g/l of other, mainly tarry, desulphonated lignins.
he purified bisulphite complex of vanillin was decomposed by aclding NaOH until the pH was 7.9.
3~ -The aqueous solution so obtained was heated to a temperature of 65C
and continuously extracted with toluene to obtain a clear yellowish toluene extract. Said extract contained 81 9/1 of vanillin while tl-e bottom product contained 24 ~/1 of vanillin.
The toluene extract obtained was washed twice with a small quar,tity of pure water so as to remove the remnants of sodium salts and any heavy phase possibly transferred during extraction. In the toluene solution so obtained the purity of vanillin was more than 98 per cent.
The toluene solution was evaporated while a small quantity of guaiacol was also evaporated along with the toluene.
The solid brown-yellow crude vanillin having a melting point of 79.5C
was distilled in vacuum at a temperature of 140C and at a pressure Oc 1 to 2 mm Hg. In the distillation, the entire distillate was recovered while the amount of the bottom product remained was about 5 per cent of the feed. The bottom product was entirely dissolved in the lye solu-tion and can be recirculated to the process. The distillate had a light yellow colour and a melting point of 80C. The distillate ob-tained was dissolved in water to form a 5 per cent solution, filtered througl- active carbon whereby the yellowish colour disappeared, and crystallized from water in the conventional manner by cooling to 5C.
The crystals were separated by filtering, and dried a-t a temperature of 60C and at a presuure of 4 to 5 mm Hg for four hours. The melting point of the crystals obtained was 81.4 to 82.2 C. The gas chromato-graphic analysis gave 0.05 per cent of acetOvanillon and 0.05 per cent of orthovanillon as impurities in the crystals. No traces of other impurities were found.
.
Claims (9)
1. A method for the preparation of vanillin using as raw material lignosulphonate obtained in the production of sul-phite cellulose, characterized by using for the preparation of vanillin only such a molecular weight fraction of lignosul-phonate that is obtained by ultrafiltration of waste pulp liquor with a membrane that has a separation limit of 5000, thereby removing low molecular weight components, preparing vanillin from said ultrafiltration residue by oxidizing and isolating said vanillin by extraction with a C3 to C6 alcohol, converting the vanillin obtained into a bisulphite complex, decomposing said bisulphite complex by adding an alkali, ex-tracting the product resulting from decomposition with an inert organic solvent as free vanillin, washing the free vanillin in said solvent with slightly alkaline water, and evaporating the solvent from the solution so treated under low vacuum so as to separate the solvent and quaiacol from the vanillin.
2. A method as claimed in claim 1, wherein said alcohol comprises n-butanol.
3. A method as claimed in claim 1, wherein said organic solvent comprises toluene.
4. A method as claimed in claim 1, wherein the lignosul-phonate raw material is prepared by ultrafiltration at a pH
of 7Ø
of 7Ø
5. A method as claimed in claim 1, characterized by evaporating the aqueous solution of vanillin removed from the alcohol product as a sodium salt to a 5- to 15-fold concentra-tion as compared with its original concentration, at which concentration the conversion into bisulphite complex is carried out by using SO2.
6. A method as claimed in claims 1 to 3, characterized by extracting the concentrated aqueous solution of vanillin bisulphite complex, to free it from non-aldehydic impurities with the same alcohol that was used to separate the vanillin from the reaction mixture, and recirculating the extract so obtained in the state free from alcohol or along with alcohol to the feed of the oxidation reactors.
7. A method as claimed in claims 1 to 3, characterized by decomposing the purified bisulphite complex in an alkaline manner, and using sodium carbonate for the decomposition, and carrying out the decomposition at the boiling point of the mixture to distillate off dissolved alcohol.
8. A method as claimed in claims 1 to 3, characterized by extracting the vanillin from the decomposed reaction mixture at the decomposition temperature with an organic solvent, where-by said organic solvent consists of toluene.
9. A method as claimed in claims 1 to 3, characterized by evaporating completely the solvent from the mixture thus obtained of vanillin and an organic solvent, by using a temp-erature up to 130°C and simultaneously applying during the evaporation a pressure up to 5 kPa.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI783799 | 1978-12-11 | ||
| FI783799A FI58906C (en) | 1978-12-11 | 1978-12-11 | FOERBAETTRAT FOERFARANDE FOER FRAMSTAELLNING AV VANILLIN |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1121384A true CA1121384A (en) | 1982-04-06 |
Family
ID=8512218
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000341137A Expired CA1121384A (en) | 1978-12-11 | 1979-12-04 | Method for the preparation of vanillin |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5851939B2 (en) |
| CA (1) | CA1121384A (en) |
| FI (1) | FI58906C (en) |
| NO (1) | NO794020L (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10017444B2 (en) | 2013-01-24 | 2018-07-10 | Rhodia Operations | Method for the purification of natural vanillin |
| CN111707754A (en) * | 2020-06-28 | 2020-09-25 | 上海应用技术大学 | Method for measuring guaiacol, ortho-vanillin, 5-methyl vanillin and 5-aldehyde vanillin in vanillin |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2933974B1 (en) * | 2008-07-18 | 2010-09-17 | Rhodia Operations | PROCESS FOR SEPARATING AROMATIC ALDEHYDE |
| WO2020226087A1 (en) * | 2019-05-08 | 2020-11-12 | 味の素株式会社 | Vanillin production method |
-
1978
- 1978-12-11 FI FI783799A patent/FI58906C/en not_active IP Right Cessation
-
1979
- 1979-12-04 CA CA000341137A patent/CA1121384A/en not_active Expired
- 1979-12-05 JP JP15793679A patent/JPS5851939B2/en not_active Expired
- 1979-12-10 NO NO794020A patent/NO794020L/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10017444B2 (en) | 2013-01-24 | 2018-07-10 | Rhodia Operations | Method for the purification of natural vanillin |
| CN111707754A (en) * | 2020-06-28 | 2020-09-25 | 上海应用技术大学 | Method for measuring guaiacol, ortho-vanillin, 5-methyl vanillin and 5-aldehyde vanillin in vanillin |
Also Published As
| Publication number | Publication date |
|---|---|
| NO794020L (en) | 1980-06-12 |
| JPS5851939B2 (en) | 1983-11-19 |
| FI783799A (en) | 1980-06-12 |
| JPS5579337A (en) | 1980-06-14 |
| FI58906C (en) | 1981-05-11 |
| FI58906B (en) | 1981-01-30 |
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