JPS5822156B2 - Continuous production method of 1,3:2,4-dibenzylidene sorbitol or (and) 1,3:2,4:5,6-tribenzylidene sorbitol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a continuous production method for benzylidene sorbitol,
More specifically, 1,3:2゜4-dibenzylidene sorbitol, 1,3:2゜4:5,6-)dibenzylidene sorbitol, and mixtures thereof are obtained by subjecting sorbitol and penzalhyde to a dehydration condensation reaction. Concerning a continuous manufacturing method.

In recent years, benzylidene sorbitols have been used in various applications as additives with specific properties.

For example, transparency and heat resistance modifiers such as polypropylene resin, rut prevention agents for asphalt pavement, COM (
cnal and oil m1xture) Anti-settling agents during fuel production and storage, paints, inks, adhesives, PV
It is used as a fluidity improver for C-paste sol, etc., and as a solidifying agent for adhesives, cosmetics, pharmaceuticals, etc.

Among the benzylidene sorbitols, 1,322,4-dibenzylidene sorbitol and 1,3:2,4:5. 6 tribenzylidene sorbitol.

[In the formula, R represents an alkyl group, an alkoxy group, or a halogen atom.

Therefore, it is important to produce the above-mentioned 1,3:2,4-dibenzylidene sorbitol, dibenzylidene sorbitol, or a mixture thereof in high yield and high selectivity.

Method for producing dibenzylidene sorbitol (Special Publication No. 48-4
3748) and a method for producing tribenzylidene sorbitol or a mixture thereof with dibenzylidene sorbitol (
(Special Publication No. 49-14758) is already known.

These production methods include an aqueous sorbitol solution, benzaldehyde, a catalyst, a water-soluble organic polar solvent as a reaction promoter, and cyclohexane as a reaction medium and/or a carbon atom having 6 to 10 carbon atoms.
The target product is obtained by charging saturated hydrocarbons into a reactor and reacting them by a batch method.

However, since all of these manufacturing methods are based on batch methods, they cannot be said to be fully satisfactory in terms of productivity when industrially implemented.

The inventors have identified 1,3:2,4-dibenzylidene sorbitols or (and) 1,3:2,4:5.

We have conducted extensive research with the aim of developing a method for producing 6-tribenzylidene sorbitol in high yield and high selectivity using a continuous process with high industrial productivity.

In the process, the batch formulation, ie sorbitol,
Attempts have been made to apply the mixture of benzaldehyde, reaction medium, catalyst and reaction promoter directly in a continuous process, but only very poor results have been obtained.

That is, since the above-mentioned mixture does not form a homogeneous liquid, it is extremely difficult to charge the mixture, and even if it is forced to react, the reaction rate and selectivity are extremely low, which is a fatal drawback.

In particular, this difficulty becomes noticeable when a large amount of the water-soluble organic polar solvent as the reaction accelerator is used, so it was thought that the use of such a reaction accelerator would actually be disadvantageous.

However, in subsequent research, among the organic solvents used as reaction accelerators in the batch method, lower alcohols can be easily mixed with sorbitol and benzaldehyde other than the reaction medium by preliminarily stirring in the presence of a catalyst. It reacts with the reaction medium to form a homogeneous liquid that can be easily fed continuously, and also acts as a reaction accelerator when the homogeneous liquid is fed into a reaction medium for continuous reaction. 1,3:2,4-dibenzylidene sorbitol or (
and) 1,3:2,4:5,6-tribenzylidene sorbitol.

The present invention has been completed based on this new knowledge.

That is, the present invention includes: (1) a first step of preliminarily reacting sorbitol, benzaldehydes, and a lower alcohol catalyst to form a homogeneous liquid; (11) the homogeneous liquid with a hydrocarbon reaction medium; a second step of continuously charging the reactor; (b) a third step of continuously reacting the homogeneous liquid in a hydrocarbon reaction medium; and (iv) a fourth step of continuously removing the resulting reaction product.
1,3:2,4-dibenzylidene sorbitol or (and) 1゜3:2,425 characterized by combining the steps
, 6-dribenzyritene sorbitol.

According to the present invention, in the step [1], sorbitol benzaldehydes and lower alcohols are mixed in the presence of a catalyst and pre-reacted, so that a homogeneous liquid product that can be easily prepared can be obtained, and the reaction can be carried out continuously in the reaction medium. Dogs can greatly contribute to improving industrial productivity.

Moreover, by changing the ratio of sorbitol and benzaldehyde, high purity 1.3:2.4-dibenzylidene sorbitol alone, high purity 1, 3:2.4:5,
It is possible to produce 6-tribenzylidene sorbitol alone or a mixture of both at a much higher yield and selectivity than in the batch method.

In the present invention, benzaldehyde and substituted benzaldehydes are used as the benzaldehydes.

Examples of substituted benzaldehydes include those having one or more lower alkyl groups, lower alkoxy groups, or halogen atoms as substituents at any position on the benzene ring.

Typical lower alkyl groups include methyl, ethyl, isopropyl, n-propyl, etc., lower alkoxy groups include mexyl, ethoxy, propoxy groups, and halogen atoms include fluorine, chlorine, bromine, etc. I can give an example.

These benzaldehydes are used in an amount of about 0.8 to 3.2 mol per 1 mol of sorbitol.

0.8 benzaldehydes per 1 mole of sorbitol
If about 2.2 mol is used, 1,322,4-dibenzylidene sorbitol can be obtained selectively and almost quantitatively, 2.8. ~ If you use about 3.2 mole, 1,322
, 4:5゜6-tribenzylidene sorbitol is obtained selectively and almost quantitatively, with an intermediate usage amount, e.g. 2.3
When the amount is about 2.7 mol, a mixture of the above dibenzylidene sorbitols and tribenzylidene sorbitols is obtained.

In the present invention, the lower alcohol has particularly 1 carbon number.
-4 can be preferably used.

Such lower alcohols include, for example, methanol, ethanol, propatool, impropatool, butaru, and at least one alcohol.
Use seeds.

When a lower alcohol is not used, or when a water-soluble organic polar solvent, which is a reaction accelerator used in the two-part method other than a lower alcohol, is used, no preliminary reaction is caused, and the object of the present invention is achieved. Not done.

In the preliminary reaction of the first step, the lower alcohol is reacted with benzaldehyde and sorbitol in the presence of a catalyst to produce a 1-acetal intermediate, a lower alcohol-sorbit exchange reaction between the acetal intermediate and sorbitol, Furthermore, a partial cyclization reaction is induced to produce a ternary mixed acetal of benzaldehydes, lower alcohols, and sorbitol, which results in a homogeneous ? It is assumed that it gives a liquid substance.

Moreover, the alcohol eliminated in the ternary mixed acetal generation reaction and the excess alcohol also act as a reaction accelerator for the reaction in the third step.

The amount of lower alcohol used may be relatively small, and generally the total weight of sorbitol and benzaldehydes is 100%.
The amount may be about 40 parts by weight or more, preferably about 70 parts by weight or more.

Although lower alcohols can be used in large amounts, the resulting improvement in the effect is not so noticeable.
The amount is preferably about 200 parts by weight, preferably about 120 parts by weight.

In the present invention, a dehydration catalyst commonly used as a catalyst for producing di- or tribenzylidene sorbitol is used as the catalyst.

Typical examples include acid catalysts such as concentrated sulfuric acid, para-toluenesulfonic acid, phosphoric acid, hydrochloric acid, zinc chloride, 02-1□ alkylbenzenesulfonic acid, G acid, and L acid.

These catalysts act as catalysts for the preliminary reaction in the first step and also as catalysts for the reaction in the third step, and the total weight of sorbitol and benzaldehydes is 10
It is usually used in an amount of 0.1 to 10 parts by weight per 0 parts by weight.

In the present invention, as the hydrocarbon reaction medium, cyclohexane and alkyl-substituted cyclohexane, linear or branched saturated hydrocarbons, panzene, alkyl-substituted benzene, etc. can be used.

Among these, those having about 6 to 10 carbon atoms are particularly suitable.

Those with less than 6 carbon atoms are generally highly volatile and may be difficult to condense and recover, while those with more than 10 carbon atoms are
Since the reaction in the third step is carried out under reflux, the reaction temperature is high, which poses a problem from an energy saving perspective.

Examples of the alkyl-substituted cyclohexane include methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, etc., linear or branched saturated hydrocarbons include hexane, octane, heptane, etc., and mixtures thereof, and the alkyl-substituted benzene includes toluene. , xylene, etc. can be mentioned as representative examples.

These hydrocarbon reaction media are expressed by the following formula % (where SB is the weight of sorbitol and BA is the weight of benzaldehydes).

) is used in an amount such that the substrate concentration is about 5 to 80%, preferably about 20 to 60%.

Even if the substrate concentration is outside the above range, there is no practical problem, but if it is less than 5%, the reaction rate tends to be slow, and if it exceeds 80%, the reaction product may be colored. In addition, the selectivity of the target part tends to decrease.

Note that if the reaction medium is present during the preliminary reaction in the first step, a homogeneous liquid product cannot be obtained, so the substrate concentration needs to be adjusted during the reaction in the third step.

The invention will now be described with reference to the accompanying drawings.

FIG. 1 is a flow sheet illustrating one embodiment of the present invention, and the present invention is not limited thereto.

First, as a first step, sorbitol (SB), benzaldehyde (BA), lower alcohol (ROH) and catalyst (CAT) are placed in a pre-reactor 2 equipped with a stirrer 1,
Make a preliminary reaction.

The preliminary reaction occurs quickly by simply mixing and stirring the above components.

The mixing and stirring temperature may be around room temperature, but since it is an exothermic reaction, it may be carried out while cooling.

It is thought that this preliminary reaction produces the ternary mixed acetals described above.

In this way, a homogeneous liquid of a charged volume is formed.

Next, as a second step, the homogeneous liquid material is continuously charged into the reactor 3 together with the reaction medium so that the substrate concentration becomes the predetermined ratio.

The reactor 3 shown in FIG. 1 is equipped with a uniform liquid material charging pipe 4 and a reaction medium charging pipe 5.

The above-mentioned homogeneous liquid is continuously charged from the charging pipe 4, and the rate is adjusted to correspond to the substrate residence time or the reaction product removal rate, and at the same time, the rate is appropriately selected according to the capacity of the reactor 3. All you have to do is decide.

Generally, the average residence time of the substrate in reactor 3;
The speed may be set so that the opening degree is 6 o'clock.

On the other hand, if the reaction medium S is present during the preliminary reaction in the first step, the desired homogeneous liquid cannot be obtained, so it must be charged through a separate pipe, and in FIG. .

Note that the reaction medium charging pipe 5 may be composed of a plurality of pipes, and for example, it is also possible to separately charge a predetermined amount from each of the front, middle, and rear stages of the reactor 3.

Further, after the preliminary reaction is completed in the first step and the homogeneous liquid substance is formed, the reaction medium and the homogeneous liquid substance may be mixed, for example, immediately before being charged into the reactor 3.

Incidentally, since the preliminary reaction in the first step occurs quickly at room temperature, in this second step, the sorbitol, benzaldehydes, lower alcohol, and catalyst can be reacted, for example, without passing through the preliminary reactor 2. It is also possible to mix in the pipe using a line mixer or the like to cause a preliminary reaction and simultaneously to continuously charge the mixture into the reactor 3.

Next, as a third step, the homogeneous liquid material after the preliminary reaction is subjected to a continuous reaction in a reaction medium in the reactor 3.

The reactor 3 is a horizontal kneader in FIG. 1, and is equipped with a cooler 6, a decanter 7, and a screw conveyor 8 for taking out reaction products.

The reaction is preferably carried out under an atmosphere of an inert gas such as nitrogen or argon, and is usually carried out under reflux.

As for the temperature, each reaction component, especially lower alcohol,
Although it may vary depending on the type of reaction medium, usage ratio, etc.
Generally about 50-180℃, preferably 65-140℃
It is sufficient to set the degree.

By this heating, the lower alcohol and the water by-produced by the reaction evaporate with or without forming an azeotrope with the reaction medium, and the reaction system is maintained at approximately constant temperature.

The evaporated material is led to a cooler 6 through a pipe 9 provided at an appropriate position at the upper end of the reactor 3, where it is cooled and condensed, and the condensate is led to a decanter 7.

In the decanter 7, the reaction medium is separated from lower alcohol and water and circulated into the reaction system.

The lower alcohol and water are taken out of the system from the decanter, but after recovery, they can be purified and reused.

As the reaction progresses, benzylidene sorbitol is produced and uniformly dispersed in the reaction medium, becoming a heterogeneous reactant in the form of a slurry with a low to high viscosity depending on the concentration of the charged substrate.

In addition, in FIG. 1, a horizontal kneader is used as the reactor 3.
Although the reactor 3 has been exemplified, any other conventional reactor 3 can be used as long as it is suitable for the above-mentioned slurry reaction and allows continuous transfer of the reaction mixture.

Typical examples include reactors with powerful stirring blades, continuous biaxial or triaxial kneaders, continuous inner roller blenders, and continuous polymerization reactors with spectacle blades.

Finally, as a fourth step, the obtained slurry-like reaction mixture is continuously taken out of the reaction system by a screw conveyor 8, cooled in accordance with conventional methods, and the acid catalyst is neutralized.
It is made into a product after going through the processes of washing, drying, and drying.

As described above, by continuously performing the first to fourth steps, the target benzylidene sorbitol can be obtained almost quantitatively with high selectivity.

The present invention will be described in detail below with reference to Examples and Comparative Examples.

Incidentally, the product was identified by comparing it with a standard product.

Example 1 The following components are mixed and stirred in a predetermined ratio at room temperature to cause a preliminary reaction, and a homogeneous liquid product is obtained.

Weight % Sorbitol 23.5 Benzaldehyde 28.2 Methanol 47.8 Para-toluenesulfonic acid 0.5 This was continuously charged into a continuous polymerization vessel with spectacle blades (manufactured by Hitachi, Ltd.) at a rate of 1 kg/hr.

At the same time, heptane was charged as a reaction medium into the polymerization vessel so that the substrate concentration was about 20%, and
The reaction is carried out at 2°C with an average residence time of 3 hours.

The azeotropic mixture that evaporates during this time is condensed in a cooler, the methanol-water layer is removed using a decanter, and the heptane is recycled into the system.

The reaction product is continuously taken out, cooled, neutralized, washed with water, filtered, and dried to obtain 1.3:2,4-dibenzylidene sorbitol.

Selectivity is 98%, yield is 97%, and purity is 99.5% Example 2 Weight % Sorbit 20.2 Tolualdehyde 27.0 Methanol 52.5 Sulfuric acid (80%) 0.3 The above components were heated at room temperature. A homogeneous liquid was obtained by mixing and stirring for a preliminary reaction, and this was charged into a general-purpose three-shaft continuous Nigu at a rate of 1.7 kg/hr. At the same time, cyclohexane was charged so that the substrate concentration was 50%, and the mixture was heated at 70± At a temperature of 1℃,
The reaction is carried out in the same manner as in Example 1.

The selectivity of the obtained 1,3:2,4-ditolylidene sorbitol is 96%, the yield is 98%, and the purity is 99.2%.

Example 3 Weight % Sorbitol 20.2 Cumin Artemis 30.0 Propatool 49.5 Sulfuric acid (80%) 0.3 The above components were mixed and stirred at room temperature until a liquid material was obtained, pre-reacted, and then reacted at 69°C. Example 2 except for reacting at temperature
In the same manner as above, 1,322,4-bis(p-isopropylbenzylidene) sorbitol was produced with a selectivity of 97% and a yield of 9.
8%, purity 99.0%.

Example 4 Weight % Sorbitol 17.9 Penzaltech 32.4 Methanol 49.4 p-+-luenesulfonic acid 0.3 The above components are mixed at room temperature and pre-reacted to form a homogeneous liquid. Continuously charged at a feeding rate of 2 kg/h, using cyclohexane as the reaction medium, substrate concentration 40%.
Example 1 except that the reaction was carried out at a temperature of 72±2°C.
In the same manner as above, 1,3:2.4:5,6-dribenzylidene sorbitol was produced with a selectivity of 97.5% and a yield of 981%.
Obtained with a purity of 99.4%.

Comparative Example 1 Weight % Sorbitol 41.4 Benzaldehyde 49.7 Dimethylformamide 8.8 Para-toluenesulfonic acid 0.5 The above ratios are mixed and stirred at room temperature for preliminary reaction.

This is continuously charged into a continuous polymerization vessel with spectacle blades at a speed of 1 ky/hr.

At the same time, heptane was charged as a reaction medium into the polymerization vessel so that the substrate concentration was approximately 20%, and 85 ± 2
The reaction is carried out at 0.degree. C. with an average residence time of 3 hours.

During this time, the azeotrope that evaporates is condensed in a cooler.

The aqueous layer is removed using a decanter and the heptane is recycled into the system.

The reaction product is continuously taken out, cooled, neutralized, washed with water, filtered through pores, and dried to obtain a product.

1.3: 2,4-dibenzylidene sorbitol selectivity is 62%, reaction rate 85%, yield 52.7%, product purity 6
It is 7.4%.

Similar results are obtained when dimethyl sulfoxide, sulfolane, etc. are used in place of dimethylformamide as the water-soluble organic polar solvent.

[Brief explanation of drawings]

) FIG. 1 is a flow sheet showing one embodiment of the continuous manufacturing method of the present invention. 1... Stirrer, 2... Pre-reactor, 3
... Reactor, 4 ... Uniform liquid material preparation pipe, 5 ... Reaction medium preparation pipe, 6 ... Cooler, 7 ...・Decanter 18...Nishkuri conveyor, 9...Piping.

Claims (1)

[Claims] 1 (:) A first step of preliminarily reacting sorbitol, benzaldehydes, and lower alcohols in the presence of a catalyst to form a homogeneous liquid, ([1) converting the homogeneous liquid into a hydrocarbon a second step of continuously charging the reactor together with the reaction medium; a third step of continuously reacting the homogeneous liquid in a hydrocarbon reaction medium; and (iψ) continuously taking out the resulting reaction product. A method for continuous production of 1,3:2,4-dibenzylidene sorbitol or (and) 1.3:2.42-5,6-dribenzylidene sorbitol, characterized in that a fourth step is combined.