JP4996233B2 - Method for producing alkyl galactoside - Google Patents

Description

  The present invention relates to a method for producing an alkyl galactoside with little residue such as unreacted products and highly condensed products.

Alkyl glycosides, which are sugar derivatives, are hypoallergenic surfactants and are known to act as foam stabilizers for other anionic surfactants.
One common method for producing alkyl glycosides is a method in which a sugar and a higher alcohol are directly reacted in the presence of an acid catalyst (see, for example, Patent Document 1). Further, a method is known in which a sugar and a lower alcohol are reacted in the presence of an acid catalyst to prepare a lower alkyl glycoside, and then an acetal exchange with a higher alcohol is performed to obtain an alkyl glycoside having a target alkyl chain (for example, Patent Document 2).
However, most of the conventional methods use glucose as a raw material sugar, and the technical problems of the method for producing alkylgalactoside using galactose as a starting material have not been sufficiently studied.

  When producing alkyl galactoside from galactose, there are some differences in its reaction behavior compared to the case of using glucose as a raw material. For example, when production of an alkyl galactoside is attempted using galactose as a raw sugar by the methods disclosed in Patent Documents 3 and 4, the sugars or the alkyl glycoside generated with the sugar and the condensation of the generated alkyl glycosides (hereinafter “ "Condensation of sugar") produces a high condensate, which significantly reduces the yield. The production of such a high condensate can be avoided to some extent by using a large excess of the higher alcohol used in the reaction. However, even in that case, unreacted galactose or galactose condensate may remain depending on the properties of the galactose used, for example, if the particle diameter is coarse or impurities are included.

Since these residues are insoluble in the reaction system, they are present as precipitates in the reaction mixture. Therefore, it is feared that the transfer of the reaction mixture becomes difficult and the remaining galactose causes coloring due to heating or the like. Moreover, when contamination with unreacted galactose or galactose condensate is not desirable due to restrictions on the use of alkyl galactoside, a step such as filtration must be added to remove the precipitate.
On the other hand, unreacted galactose and galactose condensate can be reduced to some extent by extending the reaction time, but galactose and galactose condensate cannot be completely lost, and the reaction mixture becomes more colored. The quality of the alkyl galactoside produced will be reduced.

JP 2001-151789 A Japanese Patent Publication No. 48-10716 JP-A-4-224598 Japanese Patent Laid-Open No. 62-292789

  This invention makes it a subject to provide the efficient manufacturing method of the alkyl galactoside with few residues, such as an unreacted substance and a high condensate.

In producing alkyl galactoside from galactose and aliphatic alcohol, the present inventors have added water after the reaction to dissolve and / or disperse unreacted galactose and galactose condensate, and then further ripening to perform the aging. I found that the problem could be solved.
That is, this invention provides the manufacturing method of the alkyl galactoside including the following processes 1-3.
Step 1: Step of obtaining a reaction mixture by glycosidation of galactose with an aliphatic alcohol having 1 to 22 carbon atoms Step 2: Water is added to the obtained reaction mixture to dissolve and / or disperse insoluble matter. Step of obtaining dissolution and / or dispersion Step 3: Step of dehydrating the obtained dissolution and / or dispersion and then aging to obtain alkyl galactoside

  According to the present invention, an alkyl galactoside with little residue such as unreacted galactose and galactose condensate can be obtained in high yield.

The method for producing an alkyl galactoside of the present invention includes the following steps 1 to 3, and particularly includes steps 2 and 3.
Step 1: Step of obtaining a reaction mixture by glycosidation of galactose with an aliphatic alcohol having 1 to 22 carbon atoms Step 2: Water is added to the obtained reaction mixture to dissolve and / or disperse insoluble matter. Step of obtaining dissolution and / or dispersion Step 3: Step of dehydrating the obtained dissolution and / or dispersion and then aging to obtain alkyl galactoside Hereinafter, each component and step in the production method of the present invention Will be described.

(Galactose)
The galactose used as a raw material is not particularly limited, and any of α-form, β-form, and chain structure can be used. The form is not particularly limited, and may be powder, crystal, solution or the like.
The average particle size when galactose is a powder or crystal is not particularly limited, but the median size is preferably 50 to 1000 μm, more preferably 60 to 500 μm, from the viewpoint of exerting the effects of the present invention more remarkably. The median diameter can be measured using a commercially available particle size distribution measuring apparatus.
Furthermore, raw materials containing impurities can be used as long as the quality of the resulting alkyl galactoside is not impaired. The purity of galactose to be used is not particularly limited, but from the viewpoint of exerting the effects of the present invention more remarkably, the purity is preferably 80% or more, more preferably 90% or more, particularly preferably 90% or more in terms of area ratio in gas chromatography analysis. Preferably it is 99.9% or less.

(C1-C22 aliphatic alcohol)
The C1-C22 aliphatic alcohol used as a raw material is not particularly limited. For example, methanol, ethanol, n- or isopropanol, various butanols, various hexanols, 2-ethylhexanol, various octanols, various decyl alcohols, various dodecyl alcohols, various tridecyl alcohols, various tetradecyl alcohols, various pentadecyl alcohols, various hexa Decyl alcohol, various heptadecyl alcohols, various octadecyl alcohols, various eicosyl alcohols, oleyl alcohol, coconut alcohol, oxo alcohols (alcohols produced by hydrogenating aldehydes obtained by hydroformylation of olefins), Gerve alcohol (fats Linear or branched saturated or unsaturated alcohols such as oily agents obtained by base-catalyzed condensation of aldehydes obtained by dehydrogenation of aromatic alcohols) Alkylene oxide adducts thereof, and mixtures thereof, and the like.
Among these, aliphatic alcohols having 8 to 18 carbon atoms are preferable in consideration of use of the resulting alkyl galactoside as a surfactant.

(Alkyl galactoside)
The alkyl galactoside obtained by the production method of the present invention is a compound in which a galactose residue is glycosidically bonded in an α-configuration or β-configuration to an alkyl group having 1 to 22 carbon atoms, preferably 8 to 18 carbon atoms. Moreover, the obtained alkyl galactoside is characterized in that there are few residues such as unreacted galactose and galactose condensate, and the hue (APHA) is usually 5 to 120, preferably 10 to 100.

(Process 1)
In step 1, galactose is glycosidated using an aliphatic alcohol having 1 to 22 carbon atoms to obtain a reaction mixture.
The reaction temperature in the process 1 is 50-150 degreeC normally, Preferably it is 70-130 degreeC, More preferably, it is 80-120 degreeC. The reaction temperature is preferably 50 ° C. or higher from the viewpoint of the reaction rate, and preferably 150 ° C. or lower from the viewpoint of suppressing the hue deterioration of the resulting alkylgalactoside. Further, the reaction is preferably performed under reduced pressure, and the degree of reduced pressure is preferably 0.67 to 13.3 kPa, more preferably 2.7 to 8.0 kPa, from the viewpoint of the removal efficiency of generated water and the like.
Nitrogen may be blown in order to efficiently remove water produced as a by-product in step 1. Although the amount of nitrogen blown differs depending on the amount of raw material charged, it cannot be generally stated. For example, it is preferable to blow nitrogen of about 10 to 50 ml / min with respect to the amount of galactose 0.10 mol.
Although the reaction time depends on the reaction conditions, it is preferable to appropriately monitor the consumption of raw materials and the amount of product produced and terminate the reaction at the end of the reaction.

In the present invention, alcohol as a raw material for alkyl galactoside can be used as a reaction solvent, but an auxiliary solvent can also be used to adjust the concentration of the reaction system. The auxiliary solvent used preferably has a boiling point high enough not to boil even under the reaction conditions for producing alkylgalactoside and does not adversely affect the reaction.
Although the usage-amount of an aliphatic alcohol is not specifically limited, Preferably it is 1-25 mol times with respect to galactose, More preferably, it is 2-20 mol times. The amount of the aliphatic alcohol used is preferably 1 mole or more from the viewpoint that the condensation degree of the alkyl galactoside to be produced is increased and the melting point is raised, and there is no problem in the operation of the reaction. In view of the above, it is preferably 25 mol times or less.

In step 1, it is preferable to use an acid catalyst for the purpose of increasing the reaction rate. The acid catalyst used is not particularly limited as long as it is usually used in a dehydration reaction. Examples thereof include one or more selected from strongly acidic ion exchange resins based on paratoluenesulfonic acid, methanesulfonic acid, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, styrene-divinylbenzene copolymer, and the like. Among these, paratoluenesulfonic acid is preferable from the viewpoint of solubility in the aliphatic alcohol.
The amount of the acid catalyst used is preferably 0.001 to 0.10 mol, more preferably 0.002 to 0.08 mol, and still more preferably 0.003 to 0.05 mol per mol of galactose. . If the usage-amount of an acid catalyst exists in this range, both the reaction rate and the hue of the alkyl galactoside obtained will become favorable.

When an acid catalyst is used, it is preferable to neutralize the catalyst by adding a basic substance in order to suppress the progress of sugar condensation at the stage where the reactor is returned to normal pressure after completion of aging. The basic substance used for neutralization is not particularly limited, and examples thereof include NaOH, KOH, Na ₂ CO ₃ , NaHCO ₃ , NH ₃ , and strongly basic ion exchange resins. Among these, NaOH and KOH are preferably used from the viewpoints of economy, solubility, and handleability.

(Process 2)
In step 2, water is added to the reaction mixture obtained above to dissolve and / or disperse the insoluble matter to obtain a dissolved and / or dispersed liquid.
The amount of water added in step 2 is not particularly limited as long as it is an amount capable of dissolving and / or dispersing them according to the amount of unreacted galactose or galactose condensate. Preferably, 0.01 to 10 times the weight of galactose used in Step 1 may be added as a guide.
The dissolution / dispersion temperature in step 2 is not particularly limited, but is preferably 20 to 150 ° C, more preferably 50 to 120 ° C. The dissolution / dispersion temperature is preferably 20 ° C. or higher from the viewpoint of eliminating the need to cool the reaction system or to raise the temperature again after the reaction, and suppresses the violent evaporation of the added water to reduce the amount of water remaining in the reaction system. From the viewpoint of preventing occurrence, 150 ° C. or lower is preferable.
The time taken to dissolve and / or disperse the insoluble matter by adding water varies depending on the amount of remaining insoluble matter, the amount of water added, temperature, etc., but the insoluble matter is sufficient while observing the state of the reaction system. Until dissolved and / or dispersed.

  When an acid catalyst is used in step 1, the acid catalyst may be neutralized and / or removed before adding water in step 2. Bases that can be used for neutralization are as described above. Further, when neutralization and / or removal of the acid catalyst is performed before the addition of water as described above, the acid catalyst may be added again after the subsequent dehydration step and before aging. . The types and addition amounts of the acid catalyst that can be used at this time are as described above.

(Process 3)
In Step 3, the dissolution and / or dispersion obtained above is dehydrated and then aged to obtain alkyl galactoside.
The temperature during the dehydration process in step 3 is not particularly limited, but is preferably 20 to 150 ° C, more preferably 50 to 120 ° C. The dehydration temperature is preferably 20 ° C. or higher from the viewpoint of cooling the reaction system and avoiding the need to raise the temperature again after the reaction, and 150 ° C. or lower from the viewpoint of preventing violent evaporation or bumping of the added water. Is preferred.
The pressure during the dehydration treatment is preferably 0.67 to 13.3 kPa, more preferably 2.7 to 8.0 kPa. The degree of vacuum is preferably 13.3 kPa or less from the viewpoint of efficiently removing water. Further, nitrogen may be blown in order to further increase the water removal efficiency. Although the amount of nitrogen blown differs depending on the amount of raw material charged, it cannot be generally stated. For example, it is preferable to blow nitrogen of about 10 to 50 ml / min with respect to the amount of galactose 0.10 mol.
The time for the dehydration treatment varies depending on the amount of added water, the conditions for the dehydration treatment, and the like, but may be carried out until the water is no longer distilled.

The aging temperature in the step 3 is usually 50 to 150 ° C, preferably 70 to 130 ° C, more preferably 80 to 120 ° C. The aging temperature is preferably 50 ° C. or higher from the viewpoint of aging speed, and is preferably 150 ° C. or lower from the viewpoint of suppressing the hue deterioration of the resulting alkyl galactoside.
Since insoluble components such as unreacted galactose in the reaction mixture obtained in step 1 are dissolved and / or dispersed in step 2, they are further glycosidated in the aging step of step 3 and obtained in step 1. It is considered that the residue in the reaction mixture can be efficiently removed.
Moreover, the pressure reduction degree at the time of ripening is preferably 0.67 to 13.3 kPa, more preferably 2.7 to 8.0 kPa, from the viewpoint of efficiently removing generated water.

Two kinds of A and B shown in the following table were used as galactose as a raw material. Moreover, the measurement of the median diameter and the composition analysis were performed by the following methods.
(1) Measurement of median diameter Ethanol was used as a dispersion medium using a laser diffraction / scattering particle size distribution measuring apparatus LA-920 manufactured by Horiba, Ltd.
(2) Composition analysis Gas chromatography analyzer manufactured by HEWLETT PACKARD Co., Ltd., product name: HP4890A is used, and the product name DB-1HT (inner diameter 0.25 mm, length 15 m) manufactured by J & W is used as the column. The initial temperature is 100 ° C., the heating rate is 10 ° C./min, and the final temperature is 340 ° C. for 10 minutes. Further, before gas chromatographic analysis, a sample which had been trimethylsilylated by previously reacting with trimethylsilyl chloride in the presence of pyridine was used.

Example 1
In a 500 ml five-necked flask, 0.11 g (5.6 × 10 ⁻⁴ mol) of paratoluenesulfonic acid monohydrate, 20.00 g (0.11 mol) of galactose A, 310.27 g of n-dodecyl alcohol (1. 67 mol) was weighed, a stirring blade, a nitrogen blowing port and a Liebig condenser were attached, and the inside of the system was depressurized to 5.3 kPa (40 mmHg) while stirring. After depressurization, the temperature was raised to 115 ° C. to start the dehydration reaction. At this time, nitrogen was blown into the reaction mixed solution at 25 to 50 ml / min, and the reaction was performed for 4 hours so as to efficiently remove generated water (step 1).
After completion of the reaction, the pressure was returned to normal pressure, and in a state where the reaction end product solution reached about 80 ° C., 25 g of ion exchanged water was added and dissolved / dispersed for 5 minutes (step 2). Thereafter, the system was again depressurized to 5.3 kPa (40 mmHg) and dehydrated at 80 ° C. for 30 minutes. After dehydration, the mixture was heated to 115 ° C. and aged for 2 hours while blowing nitrogen into the reaction mixture at 25 to 50 ml / min (step 3).
After completion of the reaction, the pressure was returned to normal pressure, and with the reaction end product solution at about 80 ° C., 0.05 g (6.0 × 10 ⁻⁴ mol) of a 48 mass% sodium hydroxide aqueous solution was added to neutralize the catalyst. . The insoluble matter was filtered off from the reaction mixture with a membrane filter (pore size 0.2 μm), the obtained insoluble matter was washed with hexane, dried under reduced pressure, and the insoluble matter was quantified by measuring the weight. The weight was 0.24 g. The results are shown in Table 2.

Example 2
The same operation as in Step 1 of Example 1 was performed. After completion of the reaction, the pressure was returned to normal pressure, and with the reaction end product solution at about 80 ° C., 0.05 g (6.0 × 10 ⁻⁴ mol) of a 48 mass% sodium hydroxide aqueous solution was added to neutralize the catalyst. .
25 g of ion-exchanged water was added to the neutralized reaction mixture and dissolved / dispersed for 20 minutes (step 2). Thereafter, the system was again depressurized to 5.3 kPa (40 mmHg) and dehydrated at 80 ° C. for 30 minutes. After dehydration, the system was returned to normal pressure, and 0.11 g (5.6 × 10 ⁻⁴ mol) of paratoluenesulfonic acid monohydrate was added. After reducing the pressure in the system to 5.3 kPa (40 mmHg) again, the temperature was raised to 115 ° C., and aging was performed for 30 minutes while blowing nitrogen into the reaction mixture at 25 to 50 ml / min (step 3).
After completion of the reaction, the pressure was returned to normal pressure, and with the reaction end product solution at about 80 ° C., 0.05 g (6.0 × 10 ⁻⁴ mol) of a 48 mass% sodium hydroxide aqueous solution was added to neutralize the catalyst. . The insoluble matter was filtered off from the reaction mixture with a membrane filter (pore size 0.2 μm), the obtained insoluble matter was washed with hexane, dried under reduced pressure, and the insoluble matter was quantified by measuring the weight. The weight was 0.044 g. The results are shown in Table 2.

Example 3
The same operation as in Step 1 of Example 1 was performed except that galactose B was used instead of galactose A in Step 1 of Example 1. After completion of the reaction, the pressure was returned to normal pressure, and with the reaction end product solution at about 80 ° C., 0.05 g (6.0 × 10 ⁻⁴ mol) of a 48 mass% sodium hydroxide aqueous solution was added to neutralize the catalyst. .
25 g of ion-exchanged water was added to the neutralized reaction mixture and dissolved / dispersed for 5 minutes (step 2). Thereafter, the system was again depressurized to 5.3 kPa (40 mmHg) and dehydrated at 80 ° C. for 30 minutes. After dehydration, the system was returned to normal pressure, and 0.11 g (5.6 × 10 ⁻⁴ mol) of paratoluenesulfonic acid monohydrate was added. After reducing the pressure in the system to 5.3 kPa (40 mmHg) again, the temperature was raised to 115 ° C., and aging was performed for 1 hour while blowing nitrogen into the reaction mixture at 25 to 50 ml / min (step 3).
After completion of the reaction, the pressure was returned to normal pressure, and with the reaction end product solution at about 80 ° C., 0.05 g (6.0 × 10 ⁻⁴ mol) of a 48 mass% sodium hydroxide aqueous solution was added to neutralize the catalyst. . The insoluble matter was filtered off from the reaction mixture with a membrane filter (pore size 0.2 μm), the obtained insoluble matter was washed with hexane, dried under reduced pressure, and the insoluble matter was quantified by measuring the weight. The weight was 0.34 g. The results are shown in Table 2.

Comparative Examples 1-5
In Step 1 of Example 1, the same operation as in Step 1 of Example 1 was performed, except that galactose shown in Table 2 was used instead of galactose B and reacted for a predetermined time.
After completion of the reaction, the pressure was returned to normal pressure, and with the reaction end product solution at about 80 ° C., 0.05 g (6.0 × 10 ⁻⁴ mol) of a 48 mass% sodium hydroxide aqueous solution was added to neutralize the catalyst. . The insoluble matter was separated from the reaction mixture by a membrane filter (pore size 0.2 μm), the obtained insoluble matter was washed with hexane, dried under reduced pressure, and the weight was measured to quantify the insoluble matter. The results are shown in Table 2.

From Table 2, it can be seen that Example 2 can greatly reduce the amount of insoluble matter compared to Comparative Example 1, and that there is less deterioration in hue. In addition, Comparative Examples 1 and 2 show that the insoluble content can be reduced to some extent by extending the reaction time, but the hue deteriorates. Further, although the total treatment time of Examples 1 and 2 (the sum of the reaction time, dissolution / dispersion time, dehydration time, and aging time) was shorter than the reaction time of Comparative Example 2, the amount of insoluble matter was greatly increased. It can be seen that there is little deterioration in hue.
From Example 3 and Comparative Examples 3 and 4, it can be seen that even when the type of galactose is changed, the effects of the present invention can be obtained in the same manner as described above.
In Examples 1 to 3, the same effect can be achieved even when isodecyl alcohol or the like is used instead of n-dodecyl alcohol.

Claims (5)

The manufacturing method of the alkyl galactoside containing the following processes 1-3.
Step 1: A step of glycosidating galactose with an aliphatic alcohol having 1 to 22 carbon atoms while removing generated water to obtain a reaction mixture Step 2: Water is added to the obtained reaction mixture to remove insoluble matter. Step of dissolving and / or dispersing to obtain a solution and / or dispersion Step 3: After dehydrating the obtained solution and / or dispersion, the temperature is 50 to 150 ° C. and the pressure is 0.67 to 13.3 kPa. Aging process to obtain alkyl galactoside   The method for producing an alkyl galactoside according to claim 1, wherein the aliphatic alcohol is an aliphatic alcohol having 8 to 18 carbon atoms.   The method for producing an alkyl galactoside according to claim 1 or 2, wherein the glycosidation in step 1 is carried out in the presence of an acid catalyst.   The method for producing an alkyl galactoside according to any one of claims 1 to 3, wherein the reaction temperature in step 1 is 50 to 150 ° C. The method for producing an alkyl galactoside according to claim 3 or 4 , wherein in step 2, water is added after neutralizing and / or removing the acid catalyst used in step 1, and the acid catalyst is added again before aging.