阅读说明：本技术 一种4-(2-溴乙基)苯酚的制备方法 (Preparation method of 4- (2-bromoethyl) phenol ) 是由 王传良 赵小云 于 2021-09-01 设计创作，主要内容包括：本发明公开了一种4-(2-溴乙基)苯酚的制备方法,其采用了相对易购价廉的酪醇和氢溴酸为原料,利用溴原子置换醇羟基的溴化反应,属于经典有机反应之置换卤化反应；该反应不发生多卤化,产品纯度高,收率普遍较高等技术效果；采用价廉易制造易购买的氢溴酸为溴化剂,适当的过量使用就能将反应平衡推向生成产物的方向；产物收率可达96%以上,纯度可达97.5%以上,反应液通过蒸馏浓缩处理后可以循环使用,取得非常好的技术效果。(The invention discloses a preparation method of 4- (2-bromoethyl) phenol, which adopts tyrosol and hydrobromic acid which are relatively easily purchased and cheap as raw materials, utilizes bromine atoms to replace the bromination reaction of alcoholic hydroxyl, and belongs to the replacement halogenation reaction of the classical organic reaction; the reaction does not generate polyhalogenation, and has the technical effects of high product purity, generally higher yield and the like; hydrobromic acid which is cheap, easy to manufacture and easy to purchase is used as a brominating agent, and the reaction equilibrium can be pushed to the direction of a generated product by using proper excess; the yield of the product can reach more than 96 percent, the purity can reach more than 97.5 percent, the reaction solution can be recycled after distillation and concentration treatment, and a very good technical effect is obtained.)

1. A preparation method of 4- (2-bromoethyl) phenol is characterized in that tyrosol is taken as a raw material to be subjected to bromination reaction with hydrobromic acid to obtain 4- (2-bromoethyl) phenol, after cooling crystallization, potassium bicarbonate solution and water are respectively used for washing crystallization products, and after vacuum drying, 4- (2-bromoethyl) phenol products are obtained.

2. The preparation method of 4- (2-bromoethyl) phenol according to claim 1, which is characterized by comprising the following steps:

adding hydrobromic acid into tyrosol serving as a raw material, wherein the molar ratio of the tyrosol to hydrogen bromide in the hydrobromic acid is 1: 3.0-4.8, stirring at 73-95 ℃ to perform a bromination reaction for 12-24 hours to obtain 4- (2-bromoethyl) phenol, cooling to normal temperature, and aging for 1-5 hours until crystallization is complete; filtering out reaction liquid to obtain 4- (2-bromoethyl) phenol crystal, neutralizing residual hydrobromic acid in the 4- (2-bromoethyl) phenol crystal by using potassium bicarbonate solution to generate potassium bromide, washing the potassium bromide by using water to obtain potassium bromide, filtering out the 4- (2-bromoethyl) phenol crystal, and drying in vacuum at the temperature of 60 ℃ to obtain a 4- (2-bromoethyl) phenol product;

wherein the structural formula of tyrosol is:

the structural formula of the 4- (2-bromoethyl) phenol is as follows:

the reaction formula is as follows:

+ HBr + H₂O 。

3. the method for preparing 4- (2-bromoethyl) phenol according to claim 2, wherein the bromination reaction is carried out by adding hydrobromic acid into tyrosol as a raw material, wherein the molar ratio of the tyrosol to the hydrogen bromide in the hydrobromic acid is 1: 3.5-4.5.

4. The process according to claim 2, wherein the bromination is carried out by adding tyrosol as a starting material to hydrobromic acid while introducing nitrogen.

5. The process according to claim 2, wherein the tyrosol is subjected to bromination with hydrobromic acid; cooling to 15-25 ℃, adding 4- (2-bromoethyl) phenol as seed crystal, and aging for 1-5 hours until the crystallization is complete.

6. The method according to any one of claims 1 to 5, wherein the tyrosol is used as a raw material, and hydrobromic acid is added to carry out bromination, wherein the hydrobromic acid is obtained by removing free bromine.

7. The process according to claim 6, wherein the hydrobromic acid contains 43 to 48 weight% of hydrogen bromide.

8. The method for preparing 4- (2-bromoethyl) phenol according to claim 2, wherein the reaction solution after the bromination reaction of tyrosol and hydrobromic acid is recycled, and the method comprises the following steps:

after the bromination reaction of tyrosol and hydrobromic acid is finished, cooling, crystallizing, filtering out reaction liquid, adding the reaction liquid into a distillation kettle, and distilling out moisture before the constant boiling point of the hydrobromic acid under the conditions of stirring and heating; hydrobromic acid with the hydrogen bromide content of more than 43 percent (weight) is obtained in the distillation kettle and is recycled for the bromination reaction of tyrosol and hydrobromic acid.

9. The method for preparing 4- (2-bromoethyl) phenol according to claim 2, wherein the neutralized filtrate obtained by neutralizing the 4- (2-bromoethyl) phenol crystals with the potassium bicarbonate solution and the water-washed filtrate containing potassium bromide after water washing are recycled, and the method comprises the following specific steps:

a. neutralizing a neutralization filtrate obtained after a potassium bicarbonate solution neutralizes a 4- (2-bromoethyl) phenol crystal and a water washing filtrate containing potassium bromide after water washing, removing water through evaporation, and recovering the obtained potassium bromide; then reacting with sulfuric acid to generate hydrogen bromide gas and potassium bisulfate;

the reaction formula is as follows: KBr + H₂SO₄ HBr↑+KHSO₄ ；

b. B, introducing the hydrogen bromide gas prepared in the step a into a reaction liquid filtered after the bromination reaction of tyrosol and hydrobromic acid, dissolving and absorbing at the temperature of 25 ℃ and below to obtain hydrobromic acid with the hydrogen bromide content of 43-48% (weight), and recycling the hydrobromic acid for the bromination reaction of tyrosol and hydrobromic acid.

10. The process according to claim 8 or 9, wherein the recovered hydrobromic acid is added to red phosphorus to remove free bromine, and then recycled for use in the bromination reaction of tyrosol with hydrobromic acid;

the reaction formula is as follows: 2P + 3Br₂ + 6H₂O 2H₃PO₃ +6HBr 。

Technical Field

The invention relates to the technical field of pharmaceutical chemicals, in particular to a preparation method of 4- (2-bromoethyl) phenol.

Background

4- (2-bromoethyl) phenol; international union nomenclature: 4- (2-bromoethyl) phenol; also named: 4-hydroxyphenylethyl bromide, p-hydroxyphenylethyl bromide; english alias: 4-Hydroxy-1- (2-bromoethyl) bezene, 4-hydroxyphenyl-hydrochloride; CAS14140-15-9, formula C₈H₉BrO, molecular weight 201.063;

structural formula (xvi):

physical properties: density 1.5 + -0.1 g/cm^-3Boiling point 276.5 + -15.0 deg.C (760mmHg), melting point 88-92 deg.C (lit.), flash point 121.1 + -20.4 deg.C, refractive index 1.593, vapor pressure 0.00283mmHg (25 deg.C), slightly soluble in water (1.3 g/L25 deg.C), readily soluble in alcohols, ethers and alkyl halides.

The chemical properties are as follows: the nucleophilic substitution reaction of active alkyl bromide in molecular structure is easy to occur.

The application is as follows: organic synthesis intermediates, particularly pharmaceutical synthesis intermediates; such as:

synthesis of a LTA4H hydrolase inhibitor drug, US 20080194630 a 1;

synthesizing a disease diagnosis and examination medicine, US20060083681 a 1;

synthesizing high-activity analgesic and antidepressant medicines, US20180072654A 1;

synthetic electro-optical pressure sensitive materials, US 7977020B 2;

functional ingredients in synthetic olive oil, US20090076142a 1;

synthetic motility or smooth muscle tone change related therapeutic drugs, US 5231104;

synthesis of hydrophilic fentanyl derivatives, US20180273475a 1;

synthesis of a useful quaternary ammonium compound as a muscarinic receptor antagonist, US20080269190a 1;

synthesis of prodrugs of oxazolidinone inhibitors, US20110218177a 1;

synthesis of selective sigma-1 receptor ligands, US20130102571a 1;

synthetic inert derivatives as histone demethylase inhibitors, US20200289463a 1;

synthesizing Galanthamine (GALANTAMINE) which is a specific drug for treating Alzheimer disease, synthesizing some natural alkaloid drugs and the like; more applications were developed and the use of high purity 4- (2-bromoethyl) phenol as starting material was the preferred choice for these syntheses.

The synthesis of 4- (2-bromoethyl) phenol is reported as follows:

1. barchuk, William T.; dunford, Paul j.; edwards, James p.; fourier, ane m.; karlsson, Lars; quan, Joanne m.us 20080194630 a1 [ LTA4H hydrolase inhibitors and uses thereof ] Location in Page: Page/Page column 28; the patented method comprises the following steps: tyrosol is used as a raw material to react with hydrobromic acid; this pale yellow solution was heated to 80 ℃ and stirred for 16 hours. The reaction mixture was cooled to room temperature and then extracted with dichloromethane (CH2Cl2) (3 × 50 ml), the combined extracts were filtered, concentrated under reduced pressure and dried to give the product as a tan solid.

The method can obtain crude products with higher conversion rate; but has the following disadvantages: the method has the advantages of more benzene ring bromides, impure products, difficult crystallization, extraction and separation only by using an organic solvent, more product impurities and difficult purification.

2. Moriya, tosimitsu; yoneda, Shinichiro; kawana, Keita; ikeda, Reiko; konakahara, Takeo; sakai, Norio Organic Letters, 2012, vol.14, #18 p.4842-4845, synthesized from p-hydroxyphenylacetic acid; high-pressure hydrogenation reduction is needed, the route is too long, and industrialization is difficult.

3. US20060083681 a1 [ compounds for myocardial perfusion imaging ]; Page/Page column 11; the patented method comprises the following steps: in a round bottom flask, 15 ml of methanol was added, and 4-bromoacetyl phenol (4.6mmol) was added; then, 10wt% Pd/C (10wt%, 0.10g) was added and the mixture was filled with hydrogen to hydrogenate; reacting for 10 hours, and then separating by a diatom column; the separated liquid was collected and concentrated in vacuo to obtain 4- (2-bromoethyl) phenol as a purified product.

The disadvantages of this method are: the raw materials are expensive, palladium-carbon hydrogenation is performed, the safety is poor, the product has more impurities, only a chromatographic column can be used for separation, the pollution is large, and the industrialization is difficult.

Krysin; egorova; vasil' Ev Russian Journal of General Chemistry, 2010, vol.80, #2 p.275-283; di [2- (4-hydroxypentyl) ] ethyl ether is used as a raw material; the price of raw materials is higher than that of the product; has no industrial significance.

5 Bioorganic and Medicinal Chemistry Letters, vol.9, #11 p.1619-; is equivalent to inverse synthesis and has no industrial production value.

Bioorganic and Medicinal Chemistry Letters, vol.9, #11 p.1619-1624 starting from 4-methoxyphenylacetic acid; the raw material is expensive, the route is long, hydrogenation and dealkylation are needed, and the industrial production value is not high.

Bioorganic and Medicinal Chemistry Letters, vol.9, #11 p.1619-1624 starting with 4-methoxyphenethanol; the raw materials are expensive, and dealkylation is needed, so that the method has no industrial production value.

Monatshefte fur Chemie, vol.41, p.9 with 1-methoxy-4- (2-methoxyethyl) benzene as the raw material; the raw materials are expensive, and dealkylation is needed, so that the method has no industrial production value.

Prosenko; skorocogatov; dyubchenko; pinko; kandalintseva; shakirov; pokrovsky Russian Chemical Bulletin, 2007, vol.56, #6p.1119-1124 was prepared from 2- (3, 5-di-tert-butyl-4-hydroxyphenoyl) -ethanol; the raw materials are not easy to obtain, and the industrial production value is not high.

Journal of the Chemical Society, p.1571 starting with 4- (2-Bromoethyl) aniline hydrochloride (1: 1); is equivalent to inverse synthesis and has no industrial significance.

Bulletin de la society Chimique de France, p.3427-3432 using 4-methoxy phenylacetic acid methyl ester as raw material; the raw materials are expensive, the process is complex, the route is long, hydrogenation and dealkylation are needed, and the industrial production value is not high.

Monatshefter fur Chemie, vol.41, p.89 with (E) -1- (p-Methoxyphenyl) -2-methoxylethylene as raw material; is equivalent to inverse synthesis and has no industrial production value.

Monotsuffe fur Chemie, vol.41, p.89 using 4-methoxy benzyl bromide 1- (bromomethyl) -4-methoxybenzene as raw material; expensive raw materials, long process route, high pollution and no industrial production value, and needs dealkylation.

Tetrahedron Letters, vol.52, # 28p.3551-3554 starting from bis (4- (2-bromoethyl) phenalate); is equivalent to inverse synthesis and has no industrial significance.

Monatshefte fur Chemie, vol.41, p.89 with 1-methoxy-4- (2-methoxyethyl) benzene as the raw material; the raw materials are expensive and not easy to obtain, the process route is long, dealkylation is also needed, the pollution is large, and no industrial production value exists.

At present, the preparation methods of the 4- (2-bromoethyl) phenol have some defects, particularly defects of high-purity products and industrial production processes.

With the continuous development of new applications of 4- (2-bromoethyl) phenol, the market demand for 4- (2-bromoethyl) phenol is greatly increased, and an efficient synthetic preparation method which has the advantages of easily available raw materials, mild reaction conditions, high product yield, simple purification, relatively low production cost, less three wastes, simple and convenient operation and easy clean industrial production is urgently needed to be developed.

Disclosure of Invention

In order to overcome the technical problems in the background art, the invention provides a preparation method of 4- (2-bromoethyl) phenol.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a process for preparing 4- (2-bromoethyl) phenol includes brominating tyrosol with hydrobromic acid to obtain 4- (2-bromoethyl) phenol, cooling for crystallizing, washing with potassium bicarbonate solution and water, and vacuum drying to obtain 4- (2-bromoethyl) phenol product.

The preparation method adopts tyrosol as a raw material, and the Chinese alias of tyrosol is as follows: 4-hydroxyphenylethanol, p-hydroxyphenylethanol, 2- (4-hydroxyphenyl) ethanol, 4- (2-hydroxyethyl) phenol; english name Tyrosol, english alias: 2- (4-Hydroxyphenyl) ethanol, 4-hydroxyphennetyl, alcohol, 4-Hydroxyphenylethanol, p-HPEA; international union nomenclature: 4- (2-hydroxyethyl) phenol; CAS, 501-94-0; white crystalline powder, density: 1.168 (g/m)³20/4 deg.C), relative vapor density: 4.76 (g/cm)³Air =1), melting point: 89-93 ℃, boiling point: 287.8 ℃ (atmospheric pressure), 195 ℃ (18 mmHg); the raw material is easily purchased and relatively cheap, and can also be synthesized by a plurality of methods.

Further, the preparation method of the 4- (2-bromoethyl) phenol comprises the following steps:

adding hydrobromic acid into tyrosol serving as a raw material, wherein the molar ratio of the tyrosol to hydrogen bromide in the hydrobromic acid is 1: 3.0-4.8, stirring at 73-95 ℃ to perform a bromination reaction for 12-24 hours to obtain 4- (2-bromoethyl) phenol, cooling to normal temperature, and aging for 1-5 hours until crystallization is complete; filtering out reaction liquid to obtain 4- (2-bromoethyl) phenol crystal, neutralizing residual hydrobromic acid in the 4- (2-bromoethyl) phenol crystal by using potassium bicarbonate solution to generate potassium bromide, washing the potassium bromide by using water to obtain potassium bromide, filtering out the 4- (2-bromoethyl) phenol crystal, and drying in vacuum at the temperature of 60 ℃ to obtain a 4- (2-bromoethyl) phenol product;

wherein the structural formula of tyrosol is:

the structural formula of the 4- (2-bromoethyl) phenol is as follows:

the reaction formula is as follows:

+ HBr + H₂O；

HBr +KHCO₃ KBr +H₂O +CO₂。

the bromination reaction of bromine atom replacing alcoholic hydroxyl belongs to the replacement halogenation reaction of the classical organic reaction; the reaction does not generate polyhalogenation, so the product purity is high, the yield is generally high, and the like; are frequently used in fine organic synthesis, which is a technique well known to the person skilled in the art.

The molecular structure of the alcohol and the brominating agent as well as the bromination conditions are key contributors to the outcome of the bromination reaction. Wherein the brominating agent can be selected from phosphorus bromide (PBr)₃) And bromineHydrogen bromide gas or hydrobromic acid (aqueous solution of hydrogen bromide), but phosphorus bromide is expensive and difficult to purchase, transportation is inconvenient, and the utilization rate of reaction elements is abandoned; the direct use of the hydrogen bromide gas can be implemented only by tightly matching the gas generating device and the bromination device, so that the process requirement is high, the safety is poor, and the process is abandoned; the best choice is to select cheap, easily available and easily prepared hydrobromic acid as the brominating agent.

Hydrobromic acid (Hydrobromic acid): is an aqueous solution of hydrogen bromide, which is a strong acid, and the hydrogen bromide content of the saturated hydrobromic acid at room temperature is 68.85% (weight); HBr, formula HBr, molecular weight 80.91, CAS registry 10035-10-6, constant boiling point 126 ℃ (47% wt), density 1.49g/cm flash (47%); colorless transparent to light yellow liquid with pungent sour taste; is miscible with water and can be dissolved in ethanol and acetic acid; is easily oxidized by sulfuric acid, oxygen and the like to generate free bromine which is gradually changed into yellow brown due to bromine free when exposed in air and sunlight; sealed and stored in a shady and dry place in dark and light-proof manner.

At present, the method adopting hydrobromic acid as a brominating agent has the following alternative modes:

the bromination reaction of hydrobromic acid to tyrosol is prepared in situ by acid.

The reaction formula is as follows:

+K(Na)Br+H₂SO₄ +K(Na)HSO₄ +H₂O

+K(Na)Br+H₃PO₄ +K(Na)H₂PO₄+H₂O；

wherein the sulfuric acid process results in: the yield of the 4- (2-bromoethyl) phenol can reach 80 percent; however, 3-5% of benzene ring bromide impurities (structural formula I) which are difficult to separate are contained in the product; the purity of the 4- (2-bromoethyl) phenol can only reach 94 percent, and the purity requirement of the product cannot be met; but also the disposal of the large quantities of bisulfate waste produced is a problem.

The structural formula of the benzene ring bromide impurities is as follows:(structural formula I)

Benzene rings of phenol and substituted phenol are easy to generate ortho-position and para-position bromination reaction with bromine, and when para-position is occupied by other groups, only ortho-position substitution reaction is generated; in particular, in hydrobromic acid solution, actives such as tyrosol and 4- (2-bromoethyl) phenol more readily undergo a monobromo side reaction with bromine in the ortho position, thereby producing by-products of formula I; if more bromine is present, a bis-ortho bromination side reaction is also produced. This is a basic organic synthesis reaction principle well known to the person skilled in the art.

Among these, the phosphoric acid process results: similar product yield is obtained even under the influence of the reaction stirring difficulty due to the larger viscosity of concentrated phosphoric acid, and the benzene ring bromide impurities (structural formula I) in the product are much less than those in the case of using sulfuric acid; the product can not meet the purity requirement of the product; moreover, the treatment of the product containing, excess phosphoric acid, excess hydrobromic acid and potassium dihydrogen phosphate as a by-product is very troublesome.

② the catalyst catalyzes the bromination reaction of the hydrobromic acid to the tyrosol;

the reaction formula is as follows:

+ HBr + catalyst (H)₂SO₄） +H₂O

Catalysts which may be used in addition to the representative sulfuric acid include zinc bromide (ZnBr)₂) P-toluenesulfonic acid, polystyrene sulfonic acid resin in hydrogen form (e.g. 732, D001, etc.), trifluoromethanesulfonic acid, and the like. Wherein the sulfuric acid process results in: the yield of the 4- (2-bromoethyl) phenol can reach 85 percent, but the purity is only 96 percent, and the method is also not applicable because the method also contains 2 to 5 percent of benzene ring bromide impurities (structural formula I).

Among them, the results of zinc bromide or p-toluenesulfonic acid or hydrogen-form polystyrene sulfonic acid resin (732 or D001) or trifluoromethanesulfonic acid method are: the product yield is maintained or higher, and the purity can be maintained or higher; the impurity of benzene ring bromide (structural formula I) in the product is much less than that of sulfuric acid, the product can not meet the purity requirement of the product, and the failure of the catalyst and the generated pollutants are not solved.

③ bromizing reaction of the hydrobromic acid to the tyrosol under the action of the water-carrying agent,

the reaction formula is as follows:

+HBr+ +H₂O

()

the experimental results are: the yield of the product can reach 92 percent, the purity can reach 97 percent, and the product also contains a small amount of benzene ring bromide impurities (structural formula I); the reaction solution can be recycled after concentration treatment.

However, the use of such toxic, flammable and volatile organic solvents always brings about a great safety risk and problems in the control of VoCs.

The preparation method adopts the bromination reaction of excessive hydrobromic acid and tyrosol; for the bromination of an alcohol having a strong activity such as tyrosol, hydrobromic acid which is inexpensive, easy to produce and purchase, and in which 43 to 48% of hydrogen bromide is used as a brominating agent, is used in an excess amount to drive the equilibrium of the reaction toward the direction of the product.

The reaction formula is as follows:

+ HBr (excess) +H₂O

Mixing and stirring tyrosol and hydrogen bromide in hydrobromic acid in a molar ratio of 1: 3.0-4.8, heating to perform bromination reaction, and finally cooling and crystallizing 4- (2-bromoethyl) phenol, wherein the yield of the product can reach more than 96%, the purity can reach more than 97.5%, and the product contains a small amount of benzene ring bromide impurities; the reaction solution can be recycled after concentration treatment, and a very good technical effect is obtained.

More preferably, when tyrosol is used as a raw material and hydrobromic acid is added to carry out bromination reaction, the molar ratio of tyrosol to hydrogen bromide in the hydrobromic acid is 1: 3.5-4.5. Because the mol ratio of tyrosol to hydrogen bromide in hydrobromic acid is more than 1:1.5, 4- (2-bromoethyl) phenol can be obtained after bromination reaction, but the yield of the product is low; when the hydrogen bromide in the tyrosol and the hydrobromic acid is brominated by adopting a large excess molar ratio of more than 1: 4.8, the yield of the product can be increased by more than 96 percent, but the increase is slow; when the mixing amount is 1/10mol, the conversion rate reaches 97.5%, but the reaction equipment cost is too high after the volume is doubled; the invention preferably adopts the molar ratio of tyrosol to hydrogen bromide in hydrobromic acid of 1: 3.5-4.5, so that better product yield can be obtained, and the process economy is improved.

Preferably, the tyrosol is used as a raw material, hydrobromic acid is added for bromination reaction, and nitrogen is introduced at the same time. The introduction of nitrogen can avoid hydrobromic acid from being oxidized into bromine by oxygen in the air in the bromination reaction process, improve the bromination reaction effect and avoid generating benzene ring bromide impurities (structural formula I) which are difficult to separate.

Preferably, after the tyrosol is subjected to bromination reaction with hydrobromic acid; cooling to 15-25 ℃, adding 4- (2-bromoethyl) phenol as seed crystal, and aging for 1-5 hours until the crystallization is complete. 4- (2-bromoethyl) phenol is added as seed crystal, so that the crystallization process can be controlled, and the crystallization rate and the quality of a crystallized product are greatly improved.

Preferably, when tyrosol is used as a raw material and hydrobromic acid is added to carry out bromination, the hydrobromic acid is the hydrobromic acid after the treatment of removing free bromine. Carrying out bromination reaction on the hydrobromic acid and tyrosol after the color of the hydrobromic acid is changed into light yellow to colorless after the free bromine is removed; the yield of the final cooled and crystallized 4- (2-bromoethyl) phenol product can reach 97 percent, the purity can reach 99 percent, and the product hardly contains benzene ring bromide impurities (structural formula I); the yield is improved, and simultaneously, the high-purity 4- (2-bromoethyl) phenol can be prepared.

Preferably, the hydrobromic acid contains 43-48 wt% of hydrogen bromide. The content of hydrogen bromide in hydrobromic acid is lower than 43 percent (weight), the bromination reaction time is longer than 24 hours, the time is overlong, and the yield is lower than 90 percent; and the hydrobromic acid has the hydrogen bromide content higher than 48 percent, is fuming hydrobromic acid, and is inconvenient to use and transport.

Further, in the preparation method, the reaction liquid obtained after the bromination reaction of tyrosol and hydrobromic acid can be recycled, and the preparation method comprises the following specific steps:

after the bromination reaction of tyrosol and hydrobromic acid is finished, cooling, crystallizing, filtering out reaction liquid, adding the reaction liquid into a distillation kettle, and distilling out moisture before the constant boiling point of the hydrobromic acid under the conditions of stirring and heating; hydrobromic acid with the hydrogen bromide content of more than 43 percent (weight) is obtained in the distillation kettle and is recycled for the bromination reaction of tyrosol and hydrobromic acid.

1mol of hydrobromic acid is consumed after tyrosol and excessive hydrobromic acid are subjected to bromination reaction, so that the concentration of the hydrobromic acid in a reaction liquid is reduced, a small amount of unreacted raw tyrosol is contained in the reaction liquid, and a front fraction before constant boiling point, namely a fraction before 124 ℃, is distilled, so that the concentration of the hydrobromic acid can be conveniently increased to reach the concentration required by the bromination reaction, and the reaction liquid can be recycled; wherein, the hydrobromic acid with the hydrogen bromide content of more than 43 percent obtained in the kettle can be purified by two modes: after front cut fraction is evaporated in the distillation kettle, azeotropic substances (124-128 ℃) are evaporated to obtain purified hydrobromic acid with the purity of 43-48 percent, and the quality of the hydrobromic acid is equivalent to that of commercial hydrobromic acid; the residue is impurity, and is collected and sent to professional waste treatment; or adding activated carbon into the distillation kettle to adsorb impurities in the distillation kettle, and filtering to obtain 43-48% hydrobromic acid, wherein the quality of the hydrobromic acid is equivalent to that of commercial hydrobromic acid; collecting waste activated carbon and sending the waste activated carbon to professional waste treatment;

the invention further provides a second recycling method, wherein a neutralization filtrate obtained after the potassium bicarbonate solution neutralizes 4- (2-bromoethyl) phenol crystals and a water washing filtrate containing potassium bromide after water washing can be recycled, and the method comprises the following specific steps:

a. neutralizing a neutralization filtrate obtained after a potassium bicarbonate solution neutralizes a 4- (2-bromoethyl) phenol crystal and a water washing filtrate containing potassium bromide after water washing, removing water through evaporation, and recovering the obtained potassium bromide; then reacting with sulfuric acid to generate hydrogen bromide gas and potassium bisulfate;

the reaction formula is as follows: KBr + H₂SO₄ HBr↑+KHSO₄ ；

b. B, introducing the hydrogen bromide gas prepared in the step a into a reaction liquid filtered after the bromination reaction of tyrosol and hydrobromic acid, dissolving and absorbing at the temperature of 25 ℃ or below to improve the concentration of the hydrobromic acid, so as to obtain the hydrobromic acid with the hydrogen bromide content of 43-48% (by weight), and recycling the hydrobromic acid for the bromination reaction of tyrosol and hydrobromic acid.

The recycling method is adopted, so that the discharge of wastes is greatly reduced, and the economic benefit of the preparation process is improved.

Further preferably, the hydrobromic acid obtained by the two recovery methods is added into red phosphorus to remove free bromine in the red phosphorus, and then the red phosphorus is recycled for the bromination reaction of tyrosol and hydrobromic acid;

the reaction formula is as follows: 2P + 3Br₂ + 6H₂O 2H₃PO₃ +6HBr 。

Brominating hydrobromic acid which is subjected to bromine removal treatment and becomes light yellow to colorless, and then carrying out bromination reaction with tyrosol; can greatly improve the yield and simultaneously prepare a high-purity 4- (2-bromoethyl) phenol product.

The invention has the beneficial effects that: the invention adopts tyrosol and hydrobromic acid which are relatively easy to purchase and low in price as raw materials, utilizes bromine atoms to replace the bromination reaction of alcoholic hydroxyl, and belongs to the replacement halogenation reaction of the classical organic reaction; the reaction does not generate polyhalogenation, and has the technical effects of high product purity, generally higher yield and the like; hydrobromic acid which is cheap, easy to manufacture and easy to purchase (wherein the content of hydrogen bromide is 43-48%) is used as a brominating agent, and the reaction equilibrium can be pushed to the direction of a generated product by using a proper excess amount of the brominating agent; the yield of the product can reach more than 96 percent, the purity can reach more than 97.5 percent, and the reaction solution can be recycled after being distilled and concentrated, thereby obtaining good technical effect.

Wherein, when tyrosol is taken as a raw material and hydrobromic acid is added for bromination reaction, the molar ratio of the tyrosol to the hydrogen bromide in the hydrobromic acid is 1: 3.5-4.5. Better product yield can be obtained, and the economical efficiency of the process is improved.

When tyrosol is taken as a raw material and hydrobromic acid is added for bromination reaction, nitrogen is introduced at the same time. The introduction of nitrogen can avoid hydrobromic acid from being oxidized into bromine by oxygen in the air in the bromination reaction process, improve the bromination reaction effect and avoid generating benzene ring bromide impurities (structural formula I) which are difficult to separate.

When tyrosol is taken as a raw material and hydrobromic acid is added to carry out bromination reaction, the hydrobromic acid is the hydrobromic acid after free bromine removal treatment. Carrying out bromination reaction on the hydrobromic acid and tyrosol after the color of the hydrobromic acid is changed into light yellow to colorless after the free bromine is removed; the yield of the final cooled and crystallized 4- (2-bromoethyl) phenol product can reach 97 percent, the purity can reach 99 percent, and the product hardly contains benzene ring bromide impurities (structural formula I); the yield is improved, and the high-purity 4- (2-bromoethyl) phenol is prepared at the same time.

The hydrobromic acid contains 43-48 wt% of hydrogen bromide. The content of hydrogen bromide in hydrobromic acid is lower than 43 percent (weight), the bromination reaction time is longer than 24 hours, and the yield is lower than 90 percent; and the hydrobromic acid has the hydrogen bromide content higher than 48 percent, is fuming hydrobromic acid, and is inconvenient to use and transport.

The preparation method also provides two reactant recycling methods, so that the discharge of waste after reaction is greatly reduced, the economic benefit of the preparation process is improved, and the efficiency enhancement and environmental protection of the process are realized.

Drawings

FIG. 1 is a process diagram of the preparation method of the present invention.

Detailed Description

The following examples are provided to illustrate the preparation of 4- (2-bromoethyl) phenol according to the present invention, which is prepared by subjecting tyrosol as a raw material to bromination with hydrobromic acid to obtain 4- (2-bromoethyl) phenol, cooling and crystallizing the 4- (2-bromoethyl) phenol, washing the crystallized product with potassium bicarbonate solution and water, respectively, and vacuum drying the washed product to obtain a 4- (2-bromoethyl) phenol product, wherein the process of the preparation is shown in fig. 1.

Example 1

Bromine removal treatment of commercial hydrobromic acid:

9000 g (reddish brown) of hydrobromic acid, commercially available as an industrial product having a hydrogen bromide content of 47% by weight, were measured to have a hydrogen bromide content of 45.5% by weight and a free bromine content of 2.5% by weight; adding into a 10L round four-mouth glass reaction bottle with an air pipe, a reflux condenser, a thermometer and a stirrer, introducing nitrogen to replace air in the bottle, and placing the reaction bottle in a temperature-adjusting water bath kettle; then 21 g of red phosphorus powder was added. After stirring and warming to 90 ℃ for 12 hours, the solution turned pale yellow and analyzed for HBr content of 48.0% by weight and free bromine of 180 PPm.

Example 2

Preparation of 4- (2-bromoethyl) phenol:

adding 558g (4.0mol) of tyrosol (99% of industrial product) into a 5L round four-mouth glass reaction bottle with an air pipe, a reflux condenser, a thermometer and a stirrer, introducing nitrogen to replace air in the bottle, and placing the reaction bottle in a temperature-adjusting water bath kettle; 2030 g of hydrobromic acid prepared in example 1, which contained 48% by weight of hydrogen bromide and was subjected to a debromination treatment (which contained 12.0mol of hydrogen bromide), was added; stirring and heating the reaction mixture, and continuously stirring and reacting for 24 hours at the reaction temperature of 90-95 ℃; stopping heating reaction, continuously stirring and naturally cooling, wherein light yellow crystal particles appear in reaction liquid, and continuously stirring for 5 hours after the reaction liquid is cooled to normal temperature; filtering the crystal to separate out bromination reaction liquid, neutralizing and washing the crystal by using 10% potassium bicarbonate solution, filtering, washing by using water and filtering; the resulting crystals were dried under vacuum at 60 ℃ to obtain 782.5 g of 4- (2-bromoethyl) phenol as off-white crystalline powder having an analytical purity of 99.1% (HPLC), a yield of 96.1% based on tyrosol, and no benzene ring bromide impurity (structural formula I) detected.

In addition: 1600 g of light yellow reaction liquid after bromination reaction is obtained; the hydrogen bromide content was analyzed to be 38.2% by weight.

After filtration, a potassium bicarbonate neutralized filtrate and a water washed filtrate were obtained and combined to give 1.5L of a pH of 7.5.

Example 3

Preparation of 4- (2-bromoethyl) phenol using hydrobromic acid without debromination:

the procedure of example 2 was followed except that; 3000 g (reddish brown) of commercially available commercial hydrobromic acid designated 47% without debromination were used and the bromination reaction was carried out without introduction of nitrogen. The resulting dark brown paste was deposited on the bottom of the bottle and analyzed (HPLC) for 1.8% benzene ring bromide impurity (formula I); the paste is separated, dissolved by ethanol, added with activated carbon powder for decolorization to obtain a reddish brown solution, adsorbed by a diatomite column, eluted and separated, concentrated and crystallized to obtain 689 g of light gray powder product, and the content of 4- (2-bromoethyl) phenol is analyzed (by an HPLC method) to be 96.3%, the yield is 82.1% calculated by tyrosol, and the product contains 0.5% of cyclic bromide impurities (structural formula I).

Example 4

Preparation of 4- (2-bromoethyl) phenol:

the procedure of example 2 was followed except that: the amount of hydrobromic acid subjected to bromine removal treatment is 2700 g, the reaction temperature is 80-85 ℃, and the reaction time is 16 hours; 785 g of 4- (2-bromoethyl) phenol as an off-white crystalline powder was obtained, the analytical purity was 99.2% (HPLC), the yield was 96.4% based on tyrosol, and no benzene ring bromide impurity (structural formula I) was detected.

In addition: 2270 g of a pale yellow reaction solution after bromination was obtained; the hydrogen bromide content was analyzed to be 41.0% by weight.

Also obtained was a combination of a potassium bicarbonate neutralized filtrate and a water washed filtrate at 1.5 liters and a pH of 7.5.

Example 5

Preparation of 4- (2-bromoethyl) phenol:

the procedure of example 2 was followed except that: the dosage of hydrobromic acid subjected to bromine removal treatment is 3240 g, the reaction temperature is 73-78 ℃, and the reaction time is 12 hours; 788 g of 4- (2-bromoethyl) phenol as an off-white crystalline powder was obtained, the analytical purity was 99% (HPLC), the yield was 96.5% based on tyrosol, and no benzene ring bromide impurity (structural formula I) was detected.

In addition: 2610 g of a light yellow reaction solution after bromination reaction is obtained; the hydrogen bromide content was analyzed to be 42.5% by weight.

The resulting neutralized and washed potassium bicarbonate filtrate was combined with 1.5 liters of pH 7.5.

Example 6

Preparation of 4- (2-bromoethyl) phenol:

the procedure of example 4 was followed; the difference is that after the heating reaction is stopped, 10g of 4- (2-bromoethyl) phenol is added as seed crystal, the mixture is continuously stirred and cooled in a cold water bath, the temperature is reduced to 15-25 ℃ after 1 hour, and the mixture is stirred for 1 hour and then filtered. 799 g of 4- (2-bromoethyl) phenol was obtained, the analytical purity was 99.3%, the yield was 97% based on tyrosol, and no benzene ring bromide impurity (structural formula I) was detected.

In addition: 2268 g of a pale yellow reaction solution after bromination was obtained; the hydrogen bromide content was analyzed to be 41% by weight.

The resulting neutralized and washed potassium bicarbonate filtrate was combined with 1.5 liters of pH 7.5.

Example 7

Concentrating and recovering a bromination reaction solution:

the reaction liquid after bromination reaction of the examples 2, 4 and 6 is added into a 10L four-mouth distillation flask together, the distillation is carried out by heating under stirring, after distilled water is 0.6L before 124 ℃, cooling bath is reduced to normal temperature to obtain 5715 g of light yellow hydrobromic acid, and the content of the hydrogen bromide is analyzed to be 43.2%; free bromine 240 PPm.

Example 8

Absorbing and recovering a bromination reaction solution:

combining 6 liters of the neutralization filtrate and the water washing filtrate obtained in the examples 2, 4, 5 and 6, adding the mixture into a 10 liter four-mouth distillation flask, heating the mixture under stirring, carrying out vacuum distillation and dehydration until crystals appear, and transferring the mixture to an oven to dry to obtain 265 grams of yellow solid potassium bromide; then transferring the mixture to a 0.5L four-mouth glass bottle, adding 100 g of 90% sulfuric acid, stirring and heating until gas is generated, dropwise adding 230 g of 90% sulfuric acid into the reaction bottle through a dropping bottle, and controlling the gas production speed through the dropping speed; the generated hydrogen bromide gas was introduced into 2610 g of the pale yellow reaction solution obtained in example 4 after bromination, and the reaction solution was equally divided into two serially connected 1 l absorption bottles for bubbling dissolution and absorption (the two absorption bottles were cooled with ice water, and the temperature of the absorption solution during absorption was kept below 20 ℃); after the dropwise addition of sulfuric acid, nitrogen purge was performed. The two bottles were combined to give 2750 g of pale yellow hydrobromic acid, which was analyzed to have 45.2% hydrogen bromide and 255PPm free bromine.

Example 9

Bromine removal treatment of the bromination reaction solution:

2600 g of the reaction solution after the reddish brown bromination reaction separated in example 3, 5715 g of light yellow hydrobromic acid obtained in example 7 and 2750 g of light yellow hydrobromic acid obtained in example 8 are added into a 10-liter reaction bottle, 24 g of red phosphorus powder is added, and the mixture is stirred and heated to 95 ℃ under the protection of nitrogen to react for 18 hours, so that the solution turns light yellow; after cooling to normal temperature, 10800 g of light yellow hydrobromic acid is obtained; the content of hydrogen bromide was analyzed to be 43.3% by weight, free bromine 125 PPm.

Example 10

The recovered hydrobromic acid is recycled for use in the preparation of 4- (2-bromoethyl) phenol:

the operation procedure of example 2 is followed; except that 3600 g of hydrobromic acid prepared in example 9 was added, the heating reaction was stopped, 10g of 4- (2-bromoethyl) phenol was added, the temperature was reduced in a cold water bath with continued stirring, after 2 hours the temperature was reduced to 15 ℃, and after further stirring for 2 hours, the mixture was filtered. 805 g of 4- (2-bromoethyl) phenol was obtained with an analytical purity of 99.5%, a yield of 97.9% with respect to tyrosol, and no benzene ring bromide impurity (structural formula I) was detected.

In this specification, the invention has been described with reference to specific embodiments thereof, but it will be apparent that various modifications can be made without departing from the scope of the invention. The description is thus to be regarded as illustrative instead of limiting.