LU82679A1 - PROCESS FOR PREPARING A DIACETAL OF SORBITOL AND AN AROMATIC ALDEHYDE - Google Patents

Description

OC 51.225

-8iMr * 7 “Q GRAND-DUCHY OF LUXEMBOURG

Patent No ...........................................'... .. ^ * of 1st · AUGUST 19 8o ...... Minister

Title issued from the National Economy and the Middle Classes

"LUXEMBOURG Industrial Property Service

.

. /.Ζ.ΖΛ Application for Patent of invention - I. Request

..... The company .ditei MILLIKEN. RESEARCH ..... CORP.ÛRÂT.IOK. /. E. O .. BQX. 19.27., .. (D

..... in -SBARTANBUEG, ..... State ... of..South Carolina, ..... United States ... of America., .........

..... represented .by ^ .... Monsieur ... Jacques ..... de ... Muyser. # ..... acting ..... in __________________________ (2) ..... quality-of ... representative ........................................... .................................................. .................................................. .......................................

deposit ........ this ..... first .... aoat ..... l9oo .... quatr.e. “. v ± ng.t ........ .......................... (3) ^. at ......... 15 ............ ... hours, at the Ministry of National Economy and the Middle Classes, in Luxembourg: f 1. this request for obtaining a patent for an invention concerning: ...... 5.Er.océdê..pour ..... prepar.er ..... im .... diac.êtal ... ..de ..... sor.b ± tol .... et..d .., .. un .... aldé -._. (4) .......... hyde .... aroma tique ".., .......................... .................................................. .................................................. .................................................. ...................

.................................................. .................................................. ..........................................-....... .................................................. .................................................. ........................... (5) 2. the delegation of power, dated ... SEARTABBURG_______________ on June 10 ... 19.8 .0.

3. the description in French ......... language ________________________________ of the invention in two copies; 4 ......... // -------------- drawing boards, in two copies; 5. the receipt of the fees paid to the Luxembourg Registration Office on ._.... ier .... August 198o -------------------- ---------------------------------------------------------- ---------------------------------------------------------- ---------------------------------------------------------- -------------------------------- r / yfyWqfe / aW Μ4ΦΗ Ρ / ί4ΦΝ ΦίΦ / ΦΜ ΑΦΝ4Φ1H / (6). .................................................. ........................................... filed in (7 ) ________________________________________________________________________________________________________________ on ----------------------------------- (8) in the name of __________________________________________________________________________________ ¢ 9) take up residence for him (her) and, if appointed, for his representative, in Luxembourg ____________________ —35 -, ..... bld ...... Royal ................ ...................... (io). s »requests the issuance of a patent for the subject described and represented in the appendices ^^ m ^ tées ^ - ^ ve ^^ ur ^ ment ^ of ^ this grant to ........ ............ fi______________________months.

Π. Deposit Minutes

The above application for a patent for invention has been filed with the Ministry of National Economy and the Middle Classes, Industrial Property Service in Luxembourg, dated: August £. 19-8o S "-D.

/ ^ ύβ / 7 \ f 4? v \ Pl the Minister at 3 p.m. / ^ · ** "jet -’ "* '\% - \ of the National Economy and the Middle Classes, 5 / mi il

i Ί'-ir A

v f: δ cannv \ rA a. '••• ..il \ W ^ / D. 51.225 Descriptive Brief ï filed in support of a request for

PATENT

at

Luxembourg

formed by: MILLIKEN RESEARCH CORPORATION

for: "Process for preparing a sorbitol diacetal and an aromatic aldehyde".

* V * * "* l

The present invention relates to a process for preparing a diacetal of sorbitol and an aromatic aldehyde.

The diacetals of sorbitol and aromatic aldehydes, such as, for example, dibenzylidene sorbitol, are known additives to polymers which confer remarkable properties on certain polymers. For example, dibenzylidene sorbitol t has been used as a clearing agent. polyolefins, in particular polyethylene and polypropylene, to improve the transparency of films made of such polyolefins. Although the use of diben-10 sylidene sorbitol as an additive to polymers is of great interest and is very useful, there have been some to problems in finding economical industrial processes for the preparation of dibenzylidene sorbitol having a purity sufficient to allow its use.

The invention relates to an improved process for preparing diacetals such as dibenzylidene sorbitol by condensation of sorbitol and aromatic aldehydes: and an economical industrial process for producing diacetals of sorbitol and an aromatic aldehyde, such as dibenzylidene sorbitol, useful as additives to polymers.

• Other characteristics and advantages of the invention will emerge from the detailed description which follows.

According to the process of the invention, to prepare diacetals of sorbitol and an aromatic aldehyde, an effective amount of D-sorbitol is mixed in an aqueous solution containing a catalytic amount of a mineral acid to thereby form a * ' homogeneous aqueous mixture containing the mineral acid; then an aromatic aldehyde is gradually mixed with the homogeneous aqueous mixture containing D-sorbitol at a rate sufficient to allow a practically spontaneous reaction between D-sorbitol and the aromatic aid and thus obtain an aqueous suspension containing the crude diacetal; the aqueous suspension of the crude diacetal is then neutralized and the crude diacetal is separated from the liquid phase of the neutralized aqueous suspension; the crude ketal dia-55 is then washed with water to remove the monoacetal type impurities present in the crude diacetal produced; the washed diacetal is then dried to remove practically all the residual water and to obtain a purified and dry diacetal.

1 * .1 2 4 r \ 'It should be noted with regard to the diacetals of 5 sorbitol and aromatic aldehyde prepared according to the process of the invention, that one aims to obtain the disubstituted compound, c' that is, the sorbitol compound substituted by two molecules of the aromatic aldehyde and not by one or three molecules. Thus in the case of I, benzaldehyde, the desired condensation product is dibenzylidene sorbitol and not roonobenzylidene sorbitol or tribenzylidene eorbitol *, the latter compounds being able to have other uses, but

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pJ being considered in the invention as "impurities". Other examples of diacetals according to the invention are di. (P-chlorobenzyli- d & ne) sorbitol, di (m-chlorobenzylidene) sorbitol, di (methylbenzylidene) sorbitol, etc.

The Applicant has discovered that the aqueous solution to which D-sorbitol is added must contain a mineral acid. The acid must be present in a catalytic amount which can vary greatly and which depends to some extent on the strength of the particular acid used, Generally, the catalytic amount is between about 10 and 75% by weight and preferably between about 15 and 60% by weight or even 30 and 60% by weight, relative to the total amount of 'esu present in the reaction mixture *. The preferred mineral acids are hydrochloric acid and sulfuric acid, although others can be used such as orthophosphoric acid. When hydrochloric acid is used, the preferred concentration of this acid is between about 10 and 25% by weight, preferably between 10 and 20% by weight. When sulfuric acid is used, the preferred concentration can be between about 3.0 and 60% by weight and preferably between 35 and 50% by weight.

The amount of D-sorbitol which is mixed with the aqueous solution of the mineral acid to form a homogeneous aqueous mixture containing the mineral acid can vary widely. However, the amount of D-sorbitol used must not exceed the solubility5 of D-sor-bitol in the aqueous solution of the mineral acid at the temperature at which the reaction between D-sorbitol and the aromatic aldehyde is carried out, 4 3 * t

When the desired amount of D-sor-bltol is incorporated into the aqueous solution of the mineral acid containing the above-mentioned amount of mineral acid, an aromatic aldehyde is gradually added to the homogeneous aqueous mixture containing D-sorbitol at a 5 sufficient flow rate for a practically spontaneous reaction to occur between D-sorbitol and the aromatic aldehyde. Generally, to effect this gradual addition, the aromatic aldehyde is added very slowly * to the aqueous te-mixture which is kept under In addition, the quantity of aromatic aldehyde which is added to the aqueous mixture containing -D-sorbitol is sufficient to obtain a caolar ratio of D-sorbitol to the aromatic aldehyde of approximately 1/0, '7-5 to about 1 / 1.75 and preferably of-. approximately 1/1 to approximately 1 / 1.5 and even approximately 1 / 1.25 to approximately 1 / 1.75.

A wide variety of aromatic aldehydes and mixtures of aromatic aldehydes can be used in the process of the invention. Oh may cite -as examples of such aromatic aldehydes, -benzaldehyde, -l'o-, p- and m-methylbenzaldehyde, anisaldehyde and substituted benzaldehydes having 1 to 3 substituents chosen from lower alkyl radicals, raethoxy , mono- and di-alkylamino ·, amino, 'nit-ro and halo. The preferred aromatic aldehydes are -benzaldehyde, 1er and p-chlorobenzaldehyde, m- · and p-brdmobanzaldehyde and -le'mr and p-aethylbensaldehyde.

Φη can -perform the reaction between D-sorbitol and the aromatic aldehyde to form the desired condensation product, at various temperatures. For example, in the case of benzaldehyde, it has been determined that it is possible to carry out this reaction at ordinary temperature. -'In the case of other aldehydes, r temperatures -superior-ou-even · - lower than the ordinary temperature ïpeuWrit -be ^ better'appropriées.

30 3> ës: qu tôn; a: added-aromatic aldehyde to the aqueous mixture rcohtëhânt -the -D ^ SOrbitol and the mineral acid and that the formation tlu -diacetal-has ^ produced-an aqueous suspension, neutralized the aqueous suspension with an alkaline substance such as sodium hydroxide, potassium hydroxide, sodium bicarbonate and the like. -L'a cquârit-i-té de màtière ^ âlcâllne which one uses can vary a lot,: I-1-could-be "seuhàitable · in certain applications of uti- *! .." V.

4 "*

Use an amount of alkaline material in slight excess of the amount!. ': L || necessary to neutralize the aqueous suspension although significant excess should be avoided.

t; j After having neutralized the aqueous suspension, we separate Λ, | 5 of the liquid phase of this suspension the crude diacetal which is

P

| j the solid constituent and which contains small amounts of impurity- | monoacetal tees such as monobenzylidene sorbitol. It may be desirable to incorporate a stage of washing the raw diacetal with lukewarm water to remove any residual salt formed as a result of the neutralization of the aqueous suspension and the excess of alkaline material which are present in the diacetal. gross wet. When the wet raw diacetal is washed with lukewarm water, the temperature of this water can vary greatly. However, it is considered that the best results are obtained when the water is kept at a temperature of about 20 ° C to about 40 ° C. The crude wet condensation product can then be washed with hot water to remove monoacetal type impurities. The temperature of the water used to wash the raw diacetal to remove monoacetal type impurities can vary widely.

The product practically free from monoacetal type impurities can then be dried in order to remove the residual water therefrom and to obtain the practically dry purified diacetal constituting the product. Drying can be carried out by any conventional method known in the art such as those using a vacuum oven, convection heating and the like. The drying temperature has no particular limitation as long as it suffices to effectively dry the material without decomposing it. After drying, the purified diacetal can be further purified by extraction with a relatively non-polar solvent as described in more detail below.

It may be desirable to practice the process of preparing a diacetal according to a continuous or semi-continuous procedure. In this case, it is desirable to separate the crude diacetal product from the liquid phase of the aqueous suspension before neutralization, so that the recovered liquid phase can be recycled or used in addition to the initial aqueous solution Ιι - • • ' • '••' '»' Mfa“ · '· ni, -iiianmifiiî' 5 of mineral acid and D-sorbitol. In this case, it is possible to neutralize the crude solid diacetal product separated from the liquid phase, with an aqueous solution of an alkaline material such as those mentioned above and then wash the neutralized product with hot water or a combination of 5 lukewarm and hot water as previously indicated.

The crude diacetal product can be separated from the aqueous suspension containing it by any suitable technique well known in the art such as filtration, centrifugation and the like.

"* 10. The invention is illustrated by the following nonlimiting examples.

Examples.

• Procedure A.

This procedure is used in Examples 1 to 3 15 and 10 S 12, the characteristics of which are grouped in Tables I and II below. A 70% aqueous solution of .sorbitol (135 g? 0.5 mole) is introduced into a 1 liter container fitted with a Teflon paddle stirrer, the appropriate quantity of benzaldehyde corresponding to the molar ratio of benzaldehyde to sorbitol indicated in Tables I and II and 200 g of an aqueous mineral acid solution having the indicated concentration. This reaction mixture is stirred at about 25 ° C until the viscosity is such that agitation is no longer effective. The approximately 98% acid is then neutralized with a 10% aqueous solution of sodium hydroxide 25 e £ finally the pH of the reaction mixture is brought to around 8 with 10% sodium carbonate. The solid white product is filtered, washed with water and dried at 95 ° C. in s. an oven ! . δ convection.

ί The ratio of dibenzylidene sorbitol (DBS.) to tribenzy-lidene is determined by high-performance liquid chromatography.

Iv sorbitol (TBS) in the product.

i '.

1 Procedure B.

i This operating mode is similar to operating mode A

If only the indicated molar amount J 35 of benzaldehyde is added dropwise to the reaction mixture in about 4 hours as follows: first hour: 50%, second hour: 25%, three times. reaction for a short time to reach the desired high viscosity, the product is neutralized and isolated as described in operating mode A.

Examples 1 & 5.

In example 1, procedure A is used with the theoretical molar ratio of benzaldehyde to sorbitol necessary for producing DBS (molar ratio of 2/1). The product obtained t has a DBS / TBS ratio of 75/25. The molar ratio of benzaldehyde to sorbitol is first reduced to 1.5 / 1 and then £ 1/1 in them. 10 examples 2 and 3 and the DBS / TBS ratio of the product regularly rises to 83/17. A similar effect is observed in Examples 4 and 5 where a higher concentration of the acid is used. The results are> summarized in Table I below.

Examples 6 to 9.

9

15 In Examples 6 to 9, we use procedure B

instead of procedure A and a lower molar ratio of benzaldehyde to sortibol, which further increases the DBS / TBS ratio which reaches a maximum value of 91/9 in Example 9. The results are summarized in Table I, 20 Examples 10 to 17.

In Examples 1Q to 17, we generally observe similar effects with a catalyst consisting of sulfuric acid. The results are grouped in Table II which shows the maximum DBS / TBS ratio of 94/6 which is obtains in Example 17.

Examples 10 to 17 and the values in Table II below show that the percentage yield of the product relative to the benzaldehyde used increases very significantly when the molar ratio of benzaldehyde to sorbitol decreases. This effect appears very clearly when comparing Examples 12 and 16 in which an acid concentration of 40% is used.

"

Although the melting point of the product mixture tends to be within a wide and somewhat variable range, it is evident from the results of Tables I and II that when the DBS / TBS ratio rises Importantly, the melting point of the product also tends to rise as expected. The comparison of Examples 12 and 16 clearly illustrates this effect.

7 "· ··. <

Although improving the DBS / TBS ratio as illustrated by Tables I and II is very useful, it may still be necessary in certain industrial applications to have a product containing an even higher proportion of DBS. According to US Pat. No. 4,131,612, it is possible to purify a crude DBS containing as impurities TBS and other impurities, extract it with a lower aliphatic alcohol, such as methanol, at high temperatures. The treatment described in this patent is applied with methanol to the product of Example 17 (see Table IX) with the results which appear in Table III below. As can be seen, the DBS content of the product decreases instead of increasing as expected according to the aforementioned patent, 'According to the invention, it is possible to eliminate all or even a portion of the TBS present in a product of diacetal type / triacetal 15 to increase its diacetal content by using a relatively non-polar solvent. Table III shows the results of extraction of products consisting of DBS / TBS with relatively non-polar solvents, le-toluene and 1,1,1-trichloroethane. A liquid / solid ratio of 10/1 is used as in the case of the use of methanol previously described. A significant increase in the content of DBS in particular is obtained in the case of 1,1,1-trichloroethane. The recovery of the desired product is also high. In the case of 1,1,1-trichloroethane, the liquid extract is concentrated to remove the solvent and leave a residue having a DBS / TBS ratio of 8/92.

Example 18.

A 707 aqueous solution of D-sorbitol (52 g; 0.2 mole) and of the acid is introduced into a flask fitted with a stirrer. 43% sulfuric (87.1 g). Then added dropwise 31.5 g 30 (0 * 3 mole) of benzaldehyde with vigorous stirring in one hour and forty five minutes. During the addition the temperature of the reaction mixture rises from 24 to 28 ° C. and it forms a pale yellow solid. Stirring of the suspension is continued for one hour and thirty minutes. The contents of the flask are poured into 87% aqueous sodium hydroxide with vigorous stirring to neutralize the acid. The solid is separated by filtration, and washed with cold water up to 8 * · a pH of 5.5. The solid product is suspended in water at 90 ° C for 30 minutes then filtered and the material is washed with a new quantity of hot water. The product is dried in a vacuum oven to constant weight. The yield is 42 g 5, ie a yield calculated in dibenzylidene sorbitol of 78% relative to the weight of the benzaldehyde used. The melting point of the whitish powder is 197-202 ° C while the melting point of dibenzylidene sorbitol indicated in the literature is 224 ° C. The results of the elemental analysis are as follows: Ce-6S, 7%; 10 H s 6.05%. Theoretical values for are: C “67.0%; H = 6.2%.

Example 19.

• A procedure practically similar to that of Example 18 is used, except that the amount of benzaldehyde is brought to 41 g (0.39 mole). In this case the product yield is 50.8 g (74% relative to the benzaldehyde) but the melting point is lower: 175-179 ° C. Elementary analysis, found: G "69.1; H = 6.0%,

Example 20.

According to a procedure similar to that of Example 18 but with a reduced amount of benzaldehyde (21.2 g; 0.2 mole), a yield of solid product of 25.2 g (70% relative to the benzaldehyde). The melting point of this product is again lower: 173-177 ° C. Elementary analysis, found; 25 C 1 67.5; H »5.8%.

Example- 21.

. The procedure of example 18 is again taken up again.

but the sulfuric acid concentration is reduced from 48% to 32% by weight. After completion of the addition of the benzaldehyde and the subsequent period of stirring, the amount of solid material is relatively small. The reaction mixture is heated at 70 ° C for one hour and then cooled overnight which solidifies the reaction mass. Treat as previously described to obtain 36.1 g of product (yield 52% relative to benzaldehyde) melting at 35 170-175 ° C., Elemental analysis, found: C B 68.9; H 1 ”6.2%.

4

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9 "

The values of the melting points obtained in Examples 18 to 21 illustrate the improvement in the purity of the dibenzylidenene sorbitol which is obtained according to the process of the invention in which the molar ratio of sorbitol to benzaldehyde is maintained 5 to a determined value and the benzaldehyde is brought into contact with D-sorbitol so that these compounds react practically simultaneously which prevents the formation of undesirable side products T f.

Of course, various modifications can be made by those skilled in the art to the devices or methods which have just been described only by way of nonlimiting examples without departing from the scope of the invention. 1 M '' / '' io cj o Ο β Ο o <t rs m

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Claims (12)

1. Process for producing a sorbitol diacetal and an aromatic aldehyde *, characterized in that it consists in: mixing an effective amount of D-sorbitol in an aqueous solution of a mineral acid so as to form a mixture homogeneous aqueous containing a catalytic amount of the mineral acid, gradually mix an effective amount of an aromatic aldehyde into the homogeneous aqueous mixture. a rate sufficient to allow a practically spontaneous reaction with D-sorbitcl and to form an aqueous suspension containing the crude diacetal, this effective amount of aromatic aldehyde being the amount sufficient for the molar ratio of D-sorbitol to aromatic aldehyde either between approximately 1 / 0.75 and approximately 1 / 1.75, neutralize the aqueous suspension, separate the crude diacetal from the liquid phase from the neutralized aqueous suspension, wash the separated crude diacetal with water to remove impurities of the monoacetal type present in this crude diacetal, drying the washed diacetal to eliminate practically all the residual water and then recovering the purified and practically dry diacetal product. 2. Method according to claim 1, characterized in that, chooses the aromatic aldehyde from benzaldehyde, o, p- and m-methylbenzaldehyde, anisaldehyde and substituted benzaldehydes including the benzene ring has 1 to 3 substituents chosen from lower alkyl radicals containing less than 5 carbon atoms, methoxy, mono and dialkylamino, nitro and halo. 3. Method according to claim 2, characterized in that the aromatic aldehyde is chosen from benzaldehyde, m- and pr methylbenzaldehyde, m- and p-chlorobenzaldehyde and m- and p-bromobenzaldehyde. 4. Process according to claim 1, characterized in that it additionally comprises a stage of washing the separate raw diacetal, in two stages, a first in which an effective quantity of water is maintained maintained at a temperature d about 20 to about 40 ° 0 to remove all residual salts formed as a result of neutralization of the aqueous suspension and a second performed at a higher temperature to remove other impurities of monoacetal type presented. 35 in the raw diacetal. “End - ------- - t · - · * - —.— f ♦ ♦ 4 14 5. Method according to claim 1, characterized in that the acid is hydrochloric acid and the amount of acid present in the aqueous mixture is between about 10 and 25% by weight relative to the total amount of water present in the reaction-5 mixture. 6. Method according to claim 1, characterized in that the acid is sulfuric acid and the amount of acid present in the aqueous mixture f st between about 30 and 60% by weight relative to the total amount of water present in the reaction mixture. 7. Process according to claim 1, characterized in that the molar ratio of D-sorbitol to the aromatic aldehyde is between approximately l / l and approximately 1 / 1.5. 8. Method according to claim 1, characterized in that the purified diacetal which is practically dry is subjected to additional purification by extraction with a relatively non-polar solvent in order to remove impurities of the triacetal type. 9. Method according to claim 8, characterized in that the relatively non-polar solvent is toluene or trichloro-1,1,1 ethane. 10. A process for preparing a diacetal characterized in that it consists in: mixing an effective amount of D-sorbitol with an aqueous solution of a mineral acid to form a practically homogeneous mixture containing a catalytic amount of this mineral acid, mixing gradually an effective amount of an aromatic aldehyde in the homogeneous aqueous mixture at a rate sufficient to allow an almost spontaneous reaction with D-sorbitol and to form an aqueous suspension containing the crude diacetal, this effective amount of aromatic aldehyde being sufficient quantity / to obtain a molar ratio of D-sorbitol to aromatic aldehyde of approximately 1 / 0.75 to approximately 1 / 1.75, separating the crude diacetal from the liquid phase of the aqueous suspension, neutralize the separated raw diacetal with an aqueous alkaline mixture, wash the neutralized raw diacetal with water to remove the monoacetal type impurities present in the raw diacetal, dry the diacetal tal 35 washed to remove practically all the residual water and then purify · this dried diacetal by extraction with a relatively non-solvent 15 ¥% - polar f * t to remove impurities of triacetal type and recover a diacetal product very purified practically dry. 11. Method according to claim 10, characterized in that the aromatic aldehyde is chosen from benzaldehyde, o, p- and m-methylbenzaldehyde, anisaldehyde and substituted benzaldehydes whose nucleus benzene has 1 to 3 substituents chosen from, lower alkyl radicals having less than 5 carbon atoms, · methoxy, mono and dialkylamino, nitro and halcgeno. 12. The method of claim 11, characterized in that the aromatic aldehyde is chosen from benzaldehyde, m- and p-methylbenzaldehyde, m- and p-chlorobenzaldehyde and in and p-bromobenzaldehyde . "<" ♦