JPH0333694B2 - - Google Patents

Abstract

Ethylene glycol monoaryl ethers useful as fragrance chemicals are obtained by the process of this invention whereby a phenol containing an alkali metal borohydride and alkali metal hydroxide is monoethoxylated. Ethylene glycol monophenyl ether having a consistent mild rose odor profile and free of undesirable metallic notes is obtained by the present process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved process for the monoethoxylation of phenols to produce aromatic quality ethylene glycol monoaryl ethers, such as ethylene glycol monophenyl ether.

Ethylene glycol monoaryl ethers are known. These compounds are usually obtained by reacting phenol with ethylene oxide in the presence of an alkaline catalyst. Ammonia, urea, amides,
A process using a wide variety of base catalysts such as sodium and lithium hydroxides and phenates, potassium hydroxide and the like is described in U.S. Pat. No. 2,852,566.
No. 3354227, 3364267, 3525773, 3642911
No. 3644534.

While the products obtained by such processes are suitable for most uses in industrial production, the presence of an unpleasant and irritating "metallic" odor makes them difficult to use in cosmetic formulations and fragrances. It has not yet been accepted as sufficient for the intended use. For example, the ethylene glycol monophenyl ether obtained by such a process is further disadvantageous because the undesirable metallic odor it contains masks the pleasant aroma of the ethylene glycol monophenyl ether and the fragrance ingredients used therewith. Without purification, it is not possible to use it in cosmetic formulations or as a solvent and retention agent for perfumes. Even when the ethylene glycol monophenyl ether was carefully rectified after ethoxylation to obtain a highly pure water-white product containing essentially no catalyst residues, unreacted phenols, and high adducts of ethylene oxide. The undesirable metallic odor has not yet been completely eliminated. West German published patent no.
No. 3221170 discloses a post-treatment method in which ethylene glycol monophenyl ether is brought into contact with sodium boron hydride to remove undesirable metallic odors and to obtain ethylene glycol monophenyl ether of a quality suitable for use in the fragrance field, which is highly useful. Disclosed. Treatment with sodium borohydride also
Generally eliminates the need for product rectification.

Post-treatment of polyethoxylated products (with condensation of 3 to 80 moles of ethylene oxide) with sodium borohydride for color improvement is available at Ventron Corporation Chemicals.
“Hydride Chemicals for Process Stream Purification Division”
It is reported in the technical literature in a brochure titled ``Purification'', which also describes another method for treating polyethoxylates using caustic hydroxide, which is used as a condensation catalyst to prevent the darkening that normally occurs during the reaction. A similar method has been suggested for the production of ethoxylated fatty alcohol surfactants.
PURIFICATION NEWSLETTER) December 1979
This is suggested in Monthly Issue 3 [published by Thiokol/Ventron Division]. All of the above-mentioned processes relate to the processing or production of polyethoxylates, and there is no indication that ethylene glycol monophenyl ethers of perfumery quality can be obtained by analogous processes.

We have now inadvertently produced ethylene glycol monophenyl ethers of perfumery quality by means of an improved process for the monoethoxylation of phenols in the presence of alkali metal hydroxides and alkali metal borohydrides (i.e., borohydrides). He invented the ability to obtain the following. Quite surprisingly, a product has been obtained which is suitable for use in the perfumery field, and in which all traces of the undesirable metallic odor which have hitherto been characteristically associated with such products have disappeared. In addition to the observed increase in reaction rate, an increase in the yield of monoethoxylate was observed in some cases.

The process of the present invention comprises essentially one molar equivalent of phenol maintained above its melting point with 0.01 to 1 weight percent alkali metal hydroxide and 0.01 to 1 weight percent alkali metal borohydride. It consists of reacting with ethylene oxide. Phenols correspond to the following formula, provided that R' and R'' are hydrogen or an alkyl, alkenyl or alkoxyl group having 1 to 8 carbon atoms. Most commonly, 0.05 to 0.5 percent by weight of lithium hydroxide, sodium hydroxide or potassium hydroxide is used.
Used with 0.05 to 0.5 weight percent sodium borohydride. Preferably 110℃ to 130℃
The ethoxylation is carried out at a temperature of about 1 psi to about 50 psi. The process is particularly suitable for the production of ethylene glycol monophenyl ether useful for applications in the cosmetics and perfumery fields.

In a particularly useful embodiment of the present invention, the ethylene glycol monoaryl ether obtained by the above process is steam sparged with water introduced to the ethylene glycol monoaryl ether up to about 10 percent by weight thereof. Water (steam) is introduced and dispersed beneath the surface of the ethylene glycol monoaryl ether, which is maintained at high temperature and under reduced pressure. The most common method is to hold the ethylene glycol monoaryl ether at a temperature of 75° C. to 120° C. and a pressure below 100 mm Hg and sparge with 0.5 to 5 percent by weight of water.

In other embodiments, the PH of the ethylene glycol monoaryl ether is lowered, usually to about PH 6.5-7.5, by the addition of a suitable inorganic or organic acid. Di- and higher polycarboxylic acids and hydroxy acids, especially citric acid, whose salts are insoluble in the ethylene glycol monoaryl ether of the product and can be easily removed by filtration, are particularly useful for this purpose.
Neutralized ethylene glycol monoaryl ethers can also be subjected to steam sparging to obtain a quality product for the fragrance sector with consistent gradient profiles and without any metallic odor. May be implemented.

The improved process of the present invention for the production of ethylene glycol monoaryl ethers combines alkali metal hydroxides and alkali metal borohydrides with phenols held above their melting points;
In addition, from a temperature of 100℃ to 150℃ and normal pressure
It consists of reacting with essentially one molar equivalent of ethylene oxide at pressures up to 1000 psi. In another embodiment of the invention, the resulting ethylene glycol monoaryl ether is then neutralized and, depending on the nature of the acid used for neutralization, may be subjected to filtration to remove the salts of the acid formed. good. In still other embodiments, the process also includes the additional step of sparging the ethylene glycol monoaryl ether with steam.

Phenols and various substituted phenols can be monoethoxylated in the process of this invention. Typical phenols correspond to the following formula, where R' and R'' are hydrogen or alkyl, alkenyl or alkoxyl groups having 1 to 8 carbon atoms. This process is particularly effective for phenols and monosubstituted substituents having 1 to 4 carbon atoms. They are phenols.It should be noted that phenols with substituents at the ortho position of the ring react more slowly than substituted phenols at other positions.Typical phenols that can be monoethoxylated in the present invention The types are phenol, cresol,
Ethylphenol, methoxyphenol, t-butylphenol, dimethylphenol, moldichol and the like.

In this process, 0.01
0.01 based on weight percent to 1 weight percent alkali metal hydroxides and phenols
to 1 weight percent of an alkali metal borohydride is combined with the phenol prior to the introduction of the ethylene oxide. Preferably sodium borohydride is used as the alkali metal borohydride, however other alkali metal borohydrides such as lithium borohydride and potassium borohydride can also be utilized in the process. Most commonly,
0.05 to 0.5 weight percent alkali metal hydroxide and 0.05 to 0.5 weight percent sodium borohydride are used. Suitable alkali metal hydroxides are lithium hydroxide, sodium hydroxide and potassium hydroxide.

The phenol is kept in a molten state to facilitate the addition of the alkali metal hydroxide and alkali metal borohydride. The temperature of the phenol may be any temperature above which the ethoxylation reaction can be carried out. A common practice is to feed the alkali metal hydroxide and sodium borohydride into a reactor containing phenol that is being heated to reaction temperature. The alkali metal hydroxide and sodium borohydride may be added in any order or simultaneously. The essential nature of the resulting reactants is not precisely known, but the alkali metals and boron formed from the reaction/interaction of the alkali metal hydroxides and alkali metal borohydrides with the phenols. It is believed to be a mixture of phenolates.

Typically, the ethoxylation reaction is carried out at approximately 100°C to 150°C.
℃, and most commonly 110°C to 130°C. The reaction can also be carried out at normal pressure or at elevated pressures of up to 1000 psi or more, most commonly between about 1 psi and about 50 psi.

One molar equivalent of ethylene oxide is reacted with phenol to obtain the ethylene glycol monoaryl ether. Ethylene oxide can be added to the phenol either as a liquid or as a gas, but to maximize the yield of monoethoxylate and minimize the formation of highly ethoxylated products, a closed system is preferred. If used, no excess of more than 10 percent molar should be delivered. Preferably, a little more than 5 percent molar excess of ethylene oxide is present. When some water may be present in the reaction mixture, it is preferred to keep the amount of water as low as possible. Ethylene oxide is added at a rate such that the heat generated in the reaction is controllable and there is not a large excess of ethylene oxide in the reactor at any time during the reaction period. An external cooling source will normally be required to maintain the reaction temperature within an acceptable range. The reaction time depends above all on the reaction temperature used and the particular phenol used.
The reaction is terminated when one molar equivalent of ethylene oxide has completely reacted or when all the phenol has been ethoxylated. This termination is simply accomplished by cooling the reaction mixture and draining excess ethylene oxide from the reactor.

A common method of carrying out the reaction begins by introducing phenol into the reactor with stirring. For ease of handling, the phenol is usually delivered in a molten state, although this is not required. Start heating,
Then alkali metal hydroxide and sodium borohydride were introduced. The mixture is typically stirred by bubbling nitrogen through it while applying a vacuum to facilitate removal of evolved gases. When all gas evolution is complete, the mixture is heated to reaction temperature and the ethylene oxide feed begins. The reaction is maintained at the desired temperature until one molar equivalent of ethylene oxide has reacted with the phenol. In batch reactions, the process is typically carried out in the manner described above, but with appropriate equipment and modifications it is also possible to carry out in a semi-continuous or continuous manner.

The ethylene glycol monoaryl ether obtained by the above method can be used as it is and suitable for certain general applications without further purification. For example, this product is suitable for use in certain preservative and textile applications and can be used for further reaction with various carboxylic acids for the production of esters. The ethylene glycol monophenyl ether obtained by the above process has markedly improved slope characteristics when compared to products produced under similar conditions but without the addition of sodium borohydride to the reaction. . This difference in slope is quite surprising in view of the fact that the colors of both products can be essentially the same.

Despite the vastly improved gradient of the products obtained with the process of the present invention, products intended for use in the cosmetics and perfumery fields benefit from further processing of the products. With this process it is possible to obtain ethylene glycol monoaryl ethers, in particular ethylene glycol monophenyl ethers, with a consistent slope profile without any traces of undesirable metallic odors. In a highly utilized embodiment of the invention, to achieve this result, the product is steam sparged once the ethoxylation reaction is complete. Spreading the product by steam at a temperature of 75℃ to 120℃ and 100mm
This is achieved by introducing up to 10 wt percent of water into the product, which is held at a pressure below Hg, into the fluid to form steam and disperse. Water is introduced into the product through a sparge ring or other suitable device. Preferably, 0.5 to 5 weight percent water is used and the sparging operation is carried out at a temperature of 90°C to 110°C and a pressure of less than 50 mm Hg. After the desired amount of water has been delivered, the product is then reduced to the desired moisture level - usually less than 1 percent.
More preferably it is dried to a level of less than 0.5 percent. This drying operation is easily accomplished by keeping the system under vacuum and heating after the addition of water is complete. An inert drying gas, such as nitrogen, may be passed through the product during the drying operation to facilitate moisture removal.

It may also be desirable to lower the PH of ethylene glycol monoaryl ethers obtained by the present process, which in particular have a PH of 9 or higher. For many applications, especially those in cosmetics, preservatives, and fragrance formulations, ethylene glycol monoaryl ethers are essentially neutral (PH
6.5 to 7.5), and in such cases the product is therefore neutralized by the addition of inorganic or organic acids. Inorganic acids such as sulfuric and phosphoric acids can be used. Effective organic acids include formic acid, acetic acid, propionic acid, octanoic acid, pelargonic acid, lauric acid,
Stearic acid, isostearic acid, phenylstearic acid, benzoic acid, toluic acid, oxalic acid, malonic acid, adipic acid, azelaic acid, dodecanedioic acid, phthalic acid, citric acid, tartaric acid, glycolic acid, lactic acid and similar monocarboxylic acids, polycarboxylic acids, and hydroxycarboxylic acids.

When the product is to be neutralized, it is particularly advantageous to use organic acids which form salts which are insoluble in the ethylene glycol monoaryl ether and which are therefore easier to remove than by filtration. Organic acids useful for this purpose are hydroxy acids and di- and higher poly-carboxylic acids. Organic acids, usually having about 2 to 16 carbon atoms, more preferably 4 to 12 carbon atoms, and are aliphatic organic acids are particularly useful.
Particularly useful aliphatic dicarboxylic acids include adipic acid, azelaic acid, sebacic acid and dodecanedioyl acid. Hydroxyaliphatic acids of particular use include glycolic acid, lactic acid, tartaric acid and citric acid, the latter being particularly useful in neutralizing these acids. The acid may be added in an aqueous solution to facilitate the addition of the acid to the ethylene glycol monoaryl ether. The neutralized ethylene glycol monoaryl ether may also be subjected to steam sparging in the manner described above to further enhance the grade of the neutralized product.

The invention is illustrated in further detail by the following examples.

Example 1 Phenol was heated to 60° C. under nitrogen and charged into a standard ethoxylation kettle. After vigorously dispersing and sparging the phenol with nitrogen, 0.1 weight percent potassium hydroxide and 0.1 weight percent sodium borohydride were added to the phenol. When it was possible to evacuate the reactor and maintain a vacuum level of 30 mmHg, the reactor was sealed, heated to 110°C, and the addition of ethylene oxide was started. The addition rate of ethylene oxide is to increase the temperature to 120°C while cooling.
The temperature was maintained at 130°C and adjusted to a maximum pressure of 25 psig. The reaction mixture was sampled continuously and when the phenol content reached 500 ppm, the addition of ethylene oxide was stopped and the reactor was cooled to below 100°C and evacuated. The resulting product contains 94% monoethoxylate (ethylene glycol monophenyl ether) and 98/
100 (percent transmittance measured at 440 and 550 mμ)
It had a color tone. The product had a pleasant mild rose scent. Furthermore, no metallic odor, which was associated with conventional products, was observed.

Comparative Example 1 In order to compare and demonstrate the superior quality of the product obtained by the improved process of the present invention,
The process of Example 1 was repeated without using sodium borohydride. Potassium hydroxide was added to the phenol at approximately 0.2 weight percent. Ethoxylation was completed without difficulty but at a somewhat slow rate. The final product has a 76/94 tone (440 and
550 mμ) and contained 90% monoethoxylate (ethylene glycol monophenyl ether).
However, the pungent metallic odor associated with the product completely masked the subtle rose character of the ethylene glycol monophenyl ether.

Example 2 In order to demonstrate the ability to increase the favorable fragrance characteristics of the product obtained by the process of the invention, the ethylene glycol monophenyl ether of the product obtained by the process of Example 1 was added to a 50% aqueous solution of citric acid. hand
It was neutralized to pH 7 and then steam sprayed. Steam sparging is performed while adding 1.5 weight percent water through the sparging ring at the bottom of the reactor.
The product was heated to 115° C. and the rate of water addition was adjusted to maintain a vacuum of 60 mm Hg. After the water addition was complete, heating was continued under vacuum until the water content was less than 0.2 weight percent. The product was cooled and filtered to remove insoluble salts resulting from neutralization. Ethylene glycol monophenyl ether (boiling point 245°C) contained 94% monoethoxylate and no measurable phenol. The resulting product has a pleasant, mild rose note with a hint of fresh green, making it extremely useful and possessing the desirable properties of phenethyl alcohol's rose note in a variety of perfume formulations. It was hot with fragrance. For example, a formulation of 5 parts phenethyl alcohol, 2 parts d-citronellol, 2 parts l-citronellol, 5 parts geraniol, and 1.5 parts ethylene glycol monophenyl ether is a perfume with excellent rose characteristics.

Example 3 The following reaction was carried out to demonstrate the broad applicability of the process of the present invention and the ability to obtain monoethoxylated products derived from substituted phenols. The reactor was charged with 300 g p-(t-butyl)phenol, 0.56 g potassium hydroxide, and 0.59 g sodium borohydride. reaction mixture to 125
℃ and stirred and dispersed with nitrogen. When no more gas evolution was observed, the reactor was sealed and 98 g of ethylene oxide was added at a rate to maintain the temperature and pressure at 130-140 DEG C. and 30-40 psig, respectively. The reaction continued for an additional 30 minutes. There was no trace of any objectionable metallic odor in the ethylene glycol mono-p-(t-butyl) phenyl ether product obtained.

Example 4 Ethylene glycol monophenyl ether containing 96% monoethoxylate and 0.05% phenol was prepared in a manner similar to that described in Example 1. After ethoxylation, the product had a pH of 11.8. Product samples were neutralized with various organic and inorganic acids listed below to lower the PH. Acid final pH Phosphoric acid 6.76 Hydrochloric acid 6.83 Formic acid 6.68 Acetic acid 7.10 Propionic acid 6.97 Octanoic acid 7.16 Lauric acid 7.02 Stearic acid 6.00 Benzoic acid 7.05 Example 5 The ethylene glycol monophenyl ether sample was prepared in the same manner as in Example 4. It was neutralized with various organic dicarboxylic acids and organic hydroxy acids listed below. Acids Final PH Malonic acid 6.68 Adipic acid 7.17 Azelaic acid 7.06 Dodecanedioyl acid 6.84 Hexadecanedioyl acid 7.07 Glycolic acid 7.05 Citric acid 6.41 Insoluble salts were formed during neutralization for all of the above acids. The neutralized product was then steam sparged with about 1.5 weight percent water in a conventional manner.
After drying to a moisture content below 0.2%, it was filtered to remove insoluble salts and the ethylene glycol monophenyl ether was recovered. In all cases, the slope of the product ethylene glycol monophenyl ether thus obtained was significantly improved compared to the starting material.

Example 6 The following comparative experiments are intended to demonstrate that improved reaction rates are obtained with the process of the invention. In this example, 300 g of phenol was mixed with 157 g of ethylene oxide at 125-135°C and 30-40 psig.
Two experiments were conducted in which the reaction was performed using (Indicated by Run A)
In the first experiment, 0.9g potassium hydroxide and 0.9g
of sodium borohydride is added to the phenol prior to carrying out the ethoxylation according to the method of the invention,
In the second experiment (designated Run B) only potassium hydroxide (1.82g) was added to the phenol.
In Run A, the reaction with ethylene oxide is 45
It was completed in minutes and the product obtained did not have any metallic odor. Complete ethoxylation of Run B took 60 minutes and the resulting product had a strong metallic odor. Given the fact that both products are essentially the same color,
The marked quality superiority of the ethylene glycol monophenyl ether gradient obtained from Run A was surprising.

Example 7 An autoclave was charged with 300 g p-methoxyphenol, 0.67 g potassium hydroxide and 0.70 g sodium borohydride according to the method described above. Ethylene oxide was then added over a period of 2-1/2 hours at a temperature of 130-140°C and a pressure in the range of 30-40 psig. The product was determined to contain 95.2% monoethoxylated product by chromatographic analysis. There was also no trace of an objectionable metallic odor in the product obtained.

Claims (1)

[Claims] 1. 0.01 to 1.0 weight percent alkali metal hydroxide based on phenol and 0.01 to 1 weight percent alkali metal borohydride based on phenol, maintained at a temperature equal to or higher than their melting point. A phenolic compound of a formula [However, R' and R'' are hydrogen or an alkyl, alkenyl or alkoxyl group having 1 to 8 carbon atoms], and at a temperature of 100°C to 150°C and a pressure of normal pressure to 1000psi, the essential A method for producing ethylene glycol monoaryl ethers, characterized in that the alkali metal borohydride is sodium borohydride, and the alkali metal hydroxide and boron hydride are reacted with 1 molar equivalent of ethylene oxide. Sodium and phenol standards range from 0.05 to 0.05
2. A method according to claim 1, wherein an amount of 0.5 weight percent is used and the phenolic compound is a phenol or a monosubstituted phenol having from 1 to 4 carbon atoms in the substituent. 3. The alkali metal hydroxide is potassium hydroxide and the temperature is between 110°C and 130°C and between about 1 psi and 50 psi.
3. Process according to claim 2, characterized in that the ethoxylation is carried out at a pressure between 4. The method according to any one of claims 1 to 3, further comprising the step of reducing the pH of the ethylene glycol monoaryl ether by adding an inorganic or organic acid. 5 Ethylene glycol monoaryl ether with aliphatic di- or higher poly-carboxylic acid or hydroxy acid having 2 to 16 carbon atoms to pH 6.5-7.5
The method according to claim 4, characterized in that the method is characterized in that the neutralization is carried out to the extent of. 6. The method according to claim 5, characterized in that the ethylene glycol monoaryl ether is neutralized with citric acid. 7 Further, the ethylene glycol monoaryl ether is dispersed by introducing and dispersing less than 10 weight percent of water under the surface at a temperature of 75°C to 120°C and a pressure of less than 100 mmHg, and its water content is reduced. Claims 1 to 6 also include a step of drying until the concentration is lower than 1%.
The method described in any of the paragraphs. 8 Using 0.5 to 5 weight percent water, 90
8. A method according to claim 7, wherein the sparging step is carried out at a temperature between 110°C and 110°C and a pressure below 50 mm Hg. 9. The method according to claim 8, wherein the ethylene glycol monoaryl ether is ethylene glycol monophenyl ether. 10. A process according to claim 9, which also comprises the additional step of passing the ethylene glycol monophenyl ether for removal of insoluble salts present therein.