JPH10287623A - Production of carboxylic acid ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carboxylic ester industrially advantageously, by reacting a carboxylic acid, etc., with an alcohol using a silica zirconia catalyst containing a specified ratio of more of zirconium. SOLUTION: A carboxylic acid (preferably aromatic carboxylic acid such as phthalic acid) is reacted with an alcohol (preferably a 4-18C aliphatic monohydric alcohol) in an inert gas atmosphere by adding a silica zirconia catalyst [a catalyst prepared by a sol-gel method for hydrolyzing a partial hydrolyzate of hydrolyzable silicon compound and a hydrolyzable zirconium compound in the presence of a base and having the ratio of zirconium to the total amount of silicon and zirconium of >=10 mol%, (Zr/(Si+Zr)>=10 mol%)] and esterified at 60-250 deg.C under 100-760 mmHg absolute pressure to give the objective compound in a high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a carboxylic acid ester. More specifically, the present invention relates to a method for producing a carboxylic acid ester used as a plasticizer such as a vinyl chloride resin.

[0002]

2. Description of the Related Art When industrially producing a plasticizer such as dialkyl phthalate by esterifying (anhydrous) phthalic acid with an aliphatic alcohol, a strong acid such as sulfuric acid or paratoluenesulfonic acid is used as a catalyst for the esterification reaction. And tetraalkyl titanates such as tetraisopropyl titanate and tetrabutyl titanate are known. In particular, tetraalkyl titanate catalysts are widely used because they have less side reactions such as dehydration of alcohols than strong acid catalysts and can provide high-quality carboxylic esters with little coloring.

[0003] However, since the tetraalkyl titanate catalyst is a homogeneous catalyst, there is a problem that it is difficult to separate it from an ester which is a reaction product. That is, since it is difficult to distill and separate a high-boiling carboxylic acid ester such as dialkyl phthalate, a method of hydrolyzing and precipitating the catalyst after the completion of the reaction, followed by filtration and separation is generally used. However, there has been a problem that the catalyst is not recovered and reused, and the filtration and separation takes a long time because the tetraalkyl titanate becomes a viscous gel when hydrolyzed.

In order to solve such problems, various heterogeneous solid catalysts such as a supported alkyl titanate catalyst, a heteropolyacid catalyst supported on activated carbon, and a sulfate group-containing metal oxide catalyst have been proposed. Supported alkyl titanate catalysts are those in which an alkyl titanate is supported using an inorganic compound having a hydroxyl group on the surface as a carrier. For example, JP-A-52-75684 discloses a catalyst in which a tetraalkyl titanate is supported on silica or alumina. Is disclosed. Japanese Patent Application Laid-Open No. 2-62849 discloses a methyl titanate catalyst supported on silica magnesia. These catalysts exhibit an activity comparable to that of the homogeneous titanate catalyst, but have a problem in that titanium is eluted because the bond between the carrier and the titanate is weak. Particularly when used in the production of phthalic diesters, which are mainly used as plasticizers for plastic products, the elution of titanium causes a reduction in the volume resistivity of the ester, which adversely affects the quality of the final product such as poor insulation. Is not preferred.

Further, activated carbon-supported heteropolyacids (JP-A-5
No. 7-130954) is a good catalyst for the gas phase esterification reaction, but in the case of the liquid phase reaction, the heteropolyacid is eliminated, which is problematic in terms of catalyst stability. Sulfate-containing metal oxide catalyst (Appl. Catal. A., 133 (1995) 11,
-1156) provides high esterification activity, but because of its super-acidity, it also causes side reactions such as dehydration of alcohol, and inactivation by water generated during the esterification reaction and elimination of sulfate groups occur. It cannot be used for a long time.

As described above, the heterogeneous solid catalyst does not exhibit catalytic activity (esterification activity) exceeding that of the homogeneous catalyst and is insufficient in suppressing both side reactions and elution of catalyst components. It has not yet reached a level where it can be implemented.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high yield of ester, suppress side reactions such as dehydration of alcohol, reduce elution of catalyst components, and enable recovery and reuse of catalyst. And a method for producing a carboxylic acid ester.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, when producing a carboxylic acid ester by reacting a carboxylic acid or its anhydride with an alcohol, as a catalyst. It has been found that the object can be achieved by using a silica zirconia catalyst containing zirconium at a specific ratio or more, and the present invention has been completed.

That is, the gist of the present invention is that, when a carboxylic acid ester is produced by reacting a carboxylic acid or its anhydride with an alcohol, at least silicon and zirconium are contained, and the ratio of zirconium to the total amount of silicon and zirconium is reduced. 10 mol% or more (Zr /
(Si + Zr) ≧ 10 mol%). A method for producing a carboxylic acid ester, characterized by using a silica zirconia catalyst.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the catalyst contains at least silicon and zirconium, and the ratio of zirconium to the total amount of silicon and zirconium is 10 mol% or more (Zr / (Si + Zr) ≧ 10 mol%). A silica zirconia catalyst is used. The ratio of zirconium to the total amount of silicon and zirconium is 1
It is preferably from 0 to 95%, more preferably from 10 to 70%. After the silica zirconia is sufficiently fired (for example, at 600 ° C. for 5 hours), the amount of zirconia in the silica zirconia is measured by X-ray fluorescence analysis, and the amount of silica is determined from the measured value and the amount of silica zirconia. It can be obtained by calculation.

The catalyst is preferably prepared by a sol-gel method. In the sol-gel method, a metal compound is made into a solution, the hydrolysis and polycondensation reaction of the metal compound proceeds in the solution to solidify the sol as a gel, and the gel is heated (fired) to produce a metal oxide solid. Is the way. The sol-gel method includes preparing a silica zirconia by simultaneously hydrolyzing a hydrolyzable silicon compound and a hydrolyzable zirconium compound which are catalyst precursors, and preparing a hydrolyzable silicon compound and a hydrolyzable silicon compound. There is a method of preparing silica zirconia by hydrolyzing a soluble zirconium compound in two stages. The latter involves more complicated preparation operations than the former, but since silicon and zirconium can be uniformly mixed at the atomic level, a catalyst having a high esterification activity can be obtained. Therefore, the preparation of the silica zirconia catalyst of the present invention is preferably carried out in two stages of hydrolysis.

The two-stage hydrolysis step includes a first step of partially hydrolyzing a hydrolyzable silicon compound such as alkoxysilanes or silicon halides, and then adding a hydrolyzable zirconium compound. A second step of hydrolyzing in the presence of a basic catalyst. The second step is suitable for obtaining a silica zirconia catalyst having a high esterification activity, which can be advanced in the presence of a basic catalyst. The preparation of the silica zirconia catalyst is preferably carried out in an atmosphere of an inert gas such as nitrogen in order to minimize hydrolysis by moisture in the air.

Hereinafter, a method for preparing the silica zirconia catalyst used in the present invention by a sol-gel method including a two-stage hydrolysis step will be described in detail.

Examples of the hydrolyzable silicon compound (hereinafter referred to as "silicon compound") used in the present invention include alkoxysilanes or silicon halides. Examples of the alkoxysilanes include tetramethoxysilane and tetraethoxysilane. Silane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetrakis (2-ethoxyethoxy) silane, tetrakis (2-methoxyethoxy) silane, tetrakis (2-ethylbutoxy) silane, tetraphenoxysilane, di-t -Butoxydiacetoxysilane and the like. Examples of silicon halides include tetrachlorosilane, tetrafluorosilane, tri-n-
Butoxychlorosilane, tri-i-propoxychlorosilane and the like can be exemplified. Particularly, tetraethoxysilane is preferably used because it is easily available.

In the step of partially hydrolyzing the silicon compound (first step), the silicon compound is usually diluted with an alcohol such as ethanol or 2-propanol and then hydrolyzed in order to prevent uneven hydrolysis. I do.
As the hydrolysis catalyst, an acidic catalyst such as hydrochloric acid, sulfuric acid, nitric acid, and acetic acid or a basic catalyst such as ammonia, sodium hydroxide, potassium hydroxide, potassium carbonate, ammonium carbonate, and urea are used. In order to perform uniform hydrolysis, it is preferable to use an acidic catalyst. The amount of the hydrolysis catalyst is not particularly limited, but is usually 0.01 to 1 with respect to the silicon compound.
Double equivalent, preferably 0.05 to 0.5 equivalent.

The amount of water to be added is less than 4 equivalents, usually 0.5 to 3.5 equivalents, preferably 1 to 3 equivalents to the silicon compound.
2.5 equivalents. If the amount of water is too small or too large, the dispersion of zirconium and silicon at the atomic level in silica zirconia tends to be uneven, and it is difficult to obtain a silica zirconia catalyst having high activity (high ester yield). By adjusting the amount of water added in this way,
A partial hydrolyzate of the silicon compound is obtained. The degree of partial hydrolysis is preferably from 10 to 90%, more preferably from 25 to 65%. If the hydrolysis proceeds excessively, the resulting hydrolysis product is polymerized to produce a silica oligomer, and thus it is difficult to obtain a highly active silica zirconia catalyst as described above.

The hydrolyzable zirconium compound used in the second step (hereinafter referred to as "zirconium compound")
For example, tetramethyl zirconate, tetraethyl zirconate, tetra-n-propyl zirconate, tetra-i-propyl zirconate, tetra-n-
Alkyl zirconates such as butyl zirconate, tetra-t-butyl zirconate, tetra-2-ethylhexyl zirconate and zirconium di-n-butoxide bis (2,4-pentanedionate), zirconium 2,4-pentanedionate , Zirconium diketonates such as zirconium trifluoropentanedionate and halogenated zirconiums such as zirconium tetrachloride, zirconium tetrafluoride and zirconium oxychloride, and zirconium oxynitrate and zirconium sulfate. Preferably, tetraalkyl zirconates having an alkyl group having 4 to 8 carbon atoms, which are easy to handle and inexpensive, are used.

The molar ratio of the silicon compound and the zirconium compound used for preparing the silica zirconia catalyst of the present invention is as follows:
Usually “zirconium compound / silicon compound” = 10/90
It is suitably in the range of ９９99/1, preferably 30 / 70〜95 / 5. By setting the molar ratio between the silicon compound and the zirconium compound as described above, the ratio of zirconium to the total amount of silicon and zirconium becomes 1
A silica zirconia catalyst having 0 mol% or more is obtained.
When the proportion of the zirconium compound is less than the above range,
Since the alcohol dehydration reaction occurs in the esterification reaction, the selectivity of the ester reaction is reduced, and the obtained ester is colored. If the amount is too large, the activity of the esterification reaction decreases.

The zirconium compound is usually ethanol,
-After being dispersed in an alcohol such as propanol, mixed with a partially hydrolyzed silicon compound. The mixing method is not particularly limited, but in order to uniformly disperse silicon and zirconium in silica zirconia, when the proportion of the zirconium compound is small, the zirconium compound is gradually added to the partially hydrolyzed silicon compound. A method of adding the zirconium compound is preferable, and when the proportion of the zirconium compound is large, a method of gradually adding a partially hydrolyzed silicon compound to the zirconium compound is preferable.

The basic catalyst used in the second step includes ammonia, sodium hydroxide, potassium hydroxide,
Potassium carbonate, ammonium carbonate, urea and the like can be exemplified, but ammonia is preferred because it can be easily removed by drying and baking. When an acidic catalyst is used in the above-mentioned partial hydrolysis, the amount of the basic catalyst may be usually 1.1 to 5 equivalents, preferably 1.5 to 3 equivalents of the catalyst. When used, since the reaction system is basic, it is not necessary to newly add a basic catalyst.

The amount of water used for the hydrolysis is usually 0.25 to 1 with respect to the total amount of the silicon compound and the zirconium compound.
The equivalent is 00 equivalents, preferably 2 to 10 equivalents. When the amount of water is small, the formation of a crosslinked structure of silica zirconia due to hydrolysis becomes insufficient, and the stability of the silica zirconia catalyst decreases. In addition, even if a large amount of water is used, there is no particular advantage because only the load of the subsequent filtration step increases. By adding the above amount of water, the degree of hydrolysis (second step) theoretically becomes 100%, but in fact, it is taken into the inside of the crosslinked structure in the course of its formation, Since there are some sites that are not easily hydrolyzed, the content is usually about 95 to 99%.

Usually, the basic catalyst may be conveniently added to the system in the form of an aqueous solution, but the aqueous solution may be diluted with an alcohol such as ethanol or 2-propanol.

The sol-like silica zirconia gradually gels due to hydrolysis in the presence of a basic catalyst and subsequent dehydration condensation. For aging of the gel, usually 15
It is good to leave at a temperature of ５０50 ° C. for 1 to 14 days.
The gel thus formed is filtered, washed and dried by a conventional method, and then calcined in the air. The firing temperature is usually 300
To 800 ° C, particularly preferably 500 to 700 ° C.

According to the above-mentioned preparation method, a silica zirconia catalyst suitable for producing a carboxylic acid ester can be obtained.

Next, a method for producing a carboxylic acid ester using the silica zirconia catalyst of the present invention will be described. The carboxylic acid or its anhydride and the alcohol are mixed under an inert gas atmosphere, and the silica-zirconia catalyst obtained as described above is further added. Preferably 100-2
The esterification reaction is performed at a temperature of 20 ° C. and an absolute pressure of 100 to 760 mmHg (set according to the vapor pressure of the alcohol used). The generated water is removed from the reaction system by azeotropy with the alcohol. At this time, it is also possible to use an azeotropic agent such as toluene.

The carboxylic acids in the present invention include benzoic acid, toluic acid, α- and β-naphthoic acid, o- and m-
-And monovalent aromatic carboxylic acids having 7 to 30 carbon atoms such as p-ethylbenzoic acid, o-, m- and p-phenylbenzoic acid; and aliphatic divalent acids such as adipic acid, azelaic acid and sebacic acid. Carboxylic acid, phthalic acid, isophthalic acid,
Examples thereof include aromatic polycarboxylic acids such as terephthalic acid, trimesic acid, trimellitic acid, and pyromellitic acid. Particularly, (phthalic anhydride), (trimellitic anhydride), and adipic acid are useful as a raw material of the plasticizer and are preferably used in the present invention. The carboxylic acid may be used as it is, in the form of an acid anhydride, or in a mixture of both.

Examples of the alcohol include methanol, ethanol, propanol, isopropanol, n-butanol, t-butanol, isoamyl alcohol, n-hexanol, 2-ethylhexanol, n-octanol, n-decanol, isodecanol, 2-octanol and lauryl. Alcohols, aliphatic saturated monohydric alcohols such as stearyl alcohol and ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, trimethylolpropane,
Examples thereof include aliphatic polyhydric alcohols such as sorbitol, glycerol and pentaerythritol, and phenyl group-containing alcohols such as phenol, ethylphenol and benzyl alcohol. Also two of these alcohols
Mixtures of more than one species may be used. Among them, 4 to 4 carbon atoms
A single or mixture of the ten aliphatic saturated monohydric alcohols is useful as a raw material for the plasticizer. In particular, the above-mentioned carboxylic acid esters obtained from phthalic acid (anhydride), trimellitic acid (anhydride) or adipic acid and the above-mentioned alcohols alone or in a mixture are preferably used as a plasticizer.

In such a case, the molar ratio between the alcohol and the carboxylic acid (including its anhydride) is usually “alcohol /
Carboxylic acid "= 1/1 to 10/1, preferably 2/1 to 1
A range of 5/1 is appropriate. If the molar ratio is too small, the conversion of the carboxylic acid or its anhydride into an ester is difficult to increase, while if it is too large, the amount of unreacted alcohol increases, and the burden on the circulation / recovery system is reduced. Increases and is not preferred.

The silica zirconia catalyst used in the esterification reaction can be easily separated from the product by filtering the reaction solution, and the separated catalyst can be reused as it is.
Therefore, the esterification reaction can be carried out not only by a batch method but also by a continuous method.

[0030]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. In this example, “% by weight” is simply referred to as “%”. Example 1 (Preparation of silica zirconia catalyst) Under a nitrogen atmosphere, 56.2 g (270 mmol) of tetraethoxysilane and 250 ml of ethanol were weighed into a separable flask (1 liter) and stirred at room temperature at 300 rpm. Next, a previously prepared alcoholic dilute hydrochloric acid solution (2.8 g of 35% hydrochloric acid, 10 g of demineralized water, 20 g of ethanol)
(Milliliter) was added over 15 minutes using a syringe pump to partially hydrolyze tetraethoxysilane. After further stirring for 30 minutes, a mixture of 14.0 g (equivalent to 30 mmol of zirconium) of a 70% 1-propanol solution of tetra-n-propyl zirconate (manufactured by Kishida Chemical) and 20 ml of ethanol was added over 30 minutes. After further stirring for 30 minutes, a mixture of 5 ml of 28% ammonia water and 30 ml of demineralized water was added over 30 minutes to hydrolyze (second step).
And gelled. The reaction solution was allowed to stand for 7 days to age the gel.

The obtained precipitate was separated by filtration, washed with water until no chloride ion or ammonium ion was detected in the filtrate, and dried at 100 ° C. under reduced pressure. The obtained solid was pulverized using a mortar until the particle diameter reached a value that allows it to pass through all JIS 50 mesh sieves, and then calcined at 600 ° C. for 5 hours in an air stream to obtain 19.6 g of silica zirconia. The amount of zirconia in the obtained silica zirconia was measured by a fully automatic X-ray fluorescence spectrometer (XRF: RIX3001 manufactured by Rigaku Corporation).
The ratio of zirconium to the total amount of silicon and zirconium (Zr / (Si + Zr)) was determined to be 10 mol%. (Synthesis of carboxylic acid ester (dioctyl phthalate)) In a flask equipped with a stir bar, a thermometer, a reflux tube, and an ester tube, 37 g (0.25 mol) of phthalic anhydride and 81.4 g (0.625) of 2-ethylhexanol were added. Mol) was added thereto, and the mixture was kept at 210 ° C. under a normal pressure and a nitrogen atmosphere, and the reaction was carried out for 0.5 hour while removing generated water outside the system. At this point NMR
(Nuclear magnetic resonance spectrum analysis: UNIT manufactured by Varian Inc.
The conversion of phthalic anhydride was 100%, and the yield of dioctyl phthalate (DOP) was 68% when the reaction rate was measured by Y-300), acid value, and liquid chromatography (using LC-6A manufactured by Shimadzu Corporation). Met.

Next, 4 g of the silica zirconia obtained as described above was added as a catalyst, and the mixture was again kept at 210 ° C. and reacted at normal pressure for 1 hour. Then, the degree of pressure reduction was gradually increased (0.1 mm at 560 mmHg). The reaction was carried out for 5 hours at 460 mmHg for 0.5 hour and further at 360 mmHg for 0.5 hour). As a result of measuring the amount of DOP produced by acid value measurement and liquid chromatography, the yield was 90.8%. In addition, it was found by gas chromatography that octene was by-produced with a selectivity of 0.22% (based on the charged 2-ethylhexanol).

After the completion of the esterification reaction, the reaction solution was subjected to a fully automatic X-ray fluorescence analyzer (XRF: RIX30 manufactured by Rigaku Corporation).
As a result, the elution amount of zirconium was 0.1 ppm (detection limit) or less. Example 2 43.7 g of tetraethoxysilane (21
0 mmol) and 300 ml of ethanol were weighed into a separable flask (1 liter), and 300 r at room temperature.
Stirred at pm. Then, an alcoholic dilute hydrochloric acid solution (35
% Hydrochloric acid, 8 g of demineralized water, and 20 ml of ethanol) over 15 minutes to partially hydrolyze tetraethoxysilane. After further stirring for 30 minutes, 42.1 g of tetra-n-propyl zirconate 70% 1-propanol solution (manufactured by Kishida Chemical) (zirconium 90
(Equivalent to mmol) and 40 ml of ethanol were added over 30 minutes. After continuing stirring for further 30 minutes, a mixed solution of 2 ml of 28% ammonia water and 20 ml of demineralized water was added over 30 minutes to gel. The gel aging, washing,
Drying, crushing, and firing are performed, and silica zirconia 2
3.6 g (Zr / (Si + Zr) = 30 mol%) were obtained. When a carboxylic acid ester was synthesized in the same manner as in Example 1 using this as a catalyst, the yield of DOP was 91.2%. The octene by-product rate is 0.0
It was less than 1% (detection limit).

The amount of zirconium eluted in the reaction solution after the completion of the esterification reaction was 0.1 ppm (detection limit) or less. Example 3 Under a nitrogen atmosphere, 18.8 g of tetraethoxysilane (90
Mmol) and 20 ml of ethanol were weighed into a flask (300 ml) and stirred at room temperature at 300 rpm. Then, an alcoholic dilute hydrochloric acid solution (0.94 g of 35% hydrochloric acid, 3 g of demineralized water, 10 ml of ethanol) was added over 15 minutes, and the mixture was further stirred for 30 minutes.
Next, this solution was previously weighed into a separable flask (1 liter), and 98.3 g (zirconium) of a 70% 1-propanol solution of tetra-n-propyl zirconate (manufactured by Kishida Chemical) stirred at room temperature at 300 rpm. (Equivalent to 210 mmol) and 300 ml of ethanol were added over 30 minutes. After stirring was further continued for 30 minutes, a mixture of 2 ml of 28% ammonia water and 20 ml of demineralized water was added over 30 minutes to gel. Thereafter, the respective steps of aging, washing, drying, pulverization and baking of the gel were performed in the same manner as in Example 1,
31.2 g of silica zirconia (Zr / (Si + Zr) =
70 mol%). Example 1 using this as a catalyst
When a carboxylic acid ester was synthesized in the same manner as in the above, the yield of DOP was 93.6%. The octene by-product rate was 0.01% (detection limit) or less.

The elution amount of zirconium in the reaction solution after completion of the esterification reaction was 0.1 ppm (detection limit) or less. Comparative Example 1 Example 1 was repeated except that 60.6 g (291 mmol) of tetraethoxysilane and 4.21 g (corresponding to 9 mmol of zirconium) of a 70% 1-propanol solution of tetra-n-propyl zirconate (manufactured by Kishida Chemical) were used. 18.5 g of silica zirconia (Zr / (Si + Z
r) = 3 mol%). When a carboxylic acid ester was synthesized in the same manner as in Example 1 using this as a catalyst, the yield of DOP was 88.2%. The octene by-product rate was 25.7%.

The elution amount of zirconium in the reaction solution after the completion of the esterification reaction was 0.1 ppm (detection limit) or less. Comparative Example 2 Zirconia (Norton XZ16052) was JIS
The mixture was pulverized using a mortar until the particle size passed all the 50-mesh sieves, and then calcined at 600 ° C. for 5 hours under air flow. When this was used as a catalyst and an esterification reaction was carried out in the same manner as in Example 1, the yield of DOP was 90.8%
Met. The octene by-product rate was 0.01% (detection limit) or less.

After the completion of the esterification reaction, the elution amount of zirconium in the reaction solution was 1.8 ppm.

[0038]

[Table 1]

[0039]

According to the present invention, a high-quality carboxylic acid ester with little elution of the catalyst component can be obtained with high yield and high selectivity, and the used catalyst can be reused.

Claims (6)

[Claims] When a carboxylic acid ester is produced by reacting a carboxylic acid or its anhydride with an alcohol, at least silicon and zirconium are contained, and the ratio of zirconium to the total amount of silicon and zirconium is 10 mol% or more (Zr / (Si + Zr) ≧ 10 mol%) using a silica zirconia catalyst. 2. A silica zirconia catalyst prepared by a sol-gel method by hydrolyzing a partially hydrolyzable silicon compound and a hydrolyzable zirconium compound in the presence of a basic catalyst. The method for producing a carboxylic acid ester according to claim 1, wherein 3. The method for producing a carboxylic acid ester according to claim 2, wherein the hydrolyzable silicon compound is an alkoxysilane or a silicon halide. 4. The method for producing a carboxylic acid ester according to claim 1, wherein the carboxylic acid is an aromatic carboxylic acid. 5. The method according to claim 1, wherein the carboxylic acid is phthalic acid.
4. The method for producing a carboxylic acid ester according to any one of 3. 6. The method for producing a carboxylic acid ester according to claim 1, wherein the alcohol is an aliphatic monohydric alcohol having 4 to 18 carbon atoms.