RU2164509C1 - Method for production of 2,6-di-tert-butylphenol - Google Patents

Abstract

FIELD: industrial organic synthesis. SUBSTANCE: 2,6-di-tert-butylphenol is prepared by alkylation of phenol in presence of phenol-dissolved aluminum catalyst. Desired product is isolated by high-resolution rectification and then exposed to alternate cooling-warming procedures at temperatures 35.0 +/- 0.1 C and 36.0 +/- 0.1 C, respectively. 2,6-Di-tert-butylphenol is additionally isolated from by-product streams using rectification. EFFECT: increased (up to 100%) purity of product. 2 cl, 4 dwg, 7 tbl

Description

 The invention relates to the petrochemical synthesis of shielded phenols - antioxidants for rubbers, polymers, food products, in particular the production of 2,6-di-tert-butyl-phenol.

A known method of producing 2,6-di-tert-butyl-phenol (2,6-di-TBP) by alkylation of phenol with isobutylene at 100-105 ^o C and 15-18 ata using aluminum as a stereo-regulating catalyst. (V.V. Ershov. Spatially hindered phenols. M., Chemistry, 1968, p. 37).

 Alkylation is carried out, as a rule, without solvent. The reaction mass is a mixture of 2,6-di-TBP (up to 75 wt.%), Ortho-tert-butyl-phenol (ortho-TBP) - 9%, 2,4,6-tri-tert-butyl-phenol (2 , 4,6-tri-TBP) - 9% and 2,4-di-tert-butyl-phenol (2,4-di-TBP). The catalyst is destroyed by water, releasing 2,6-di-TBP by distillation distillation.

 The disadvantages of the method are the low yield of 2,6-di-TBP and the lack of purity of the product.

 Known methods for producing 2,6-di-TBP of high purity (99.98% - 100%) and with a yield of up to 87 wt.%, Including alkylation of phenol with isobutylene-containing fraction using modified alkylation catalysts that increase the selectivity of the process. (RF patent 1679753, C 07 C 39/06, 37/14, application. 11.01.95, publ. 10.11.96, bull. N 31).

The catalyst is deactivated with water or propylene oxide and 2,6-di-TBP is isolated by distillation under vacuum at 20 mm Hg at 132 ^° C. The resulting 2,6-di-TBP does not contain impurities.

 However, the implementation of the method in industrial production is problematic due to the complexity of the preparation of the used catalysts and the scarcity of their components - the products of the interaction of tetraphenoxyaluminic acid with 2,2-dimethylchromate in the first of these methods and aluminum tetraphenoxyaluminate in the second.

 In the industrial production of 2,6-di-TBP, aluminum phenolate and aluminum dissolved in phenol are used as alkylation catalysts. (UK patent 1062298, class C 2 C, publ. 1967, US Pat. N 1137444, class 12 G 16, publ. 1965, AS USSR 783297, C 07 C 39/06, 37/14).

 When using an isobutylene-containing fraction or isobutylene as an alkylating agent and isolating the target product by distillation, 2,6-di-TBP is obtained with a yield of up to 78 wt.%, With a purity of 99.6 wt.%.

 When implementing these methods on an industrial scale, it is not possible to achieve a higher purity of the product; the increase in the productivity of the columns and the reflux number entails energy costs that do not justify a slight increase in the quality of the resulting 2,6-di-TBP.

Closest to the claimed technical essence is the method used in production for the production of 2,6-di-TBP, including the alkylation of phenol with an isobutylene-containing fraction at 90-110 ^o C and 6-10 ata, using aluminum dissolved in phenol as a catalyst (0 , 1-0.2 wt.% Al), then the stage of deactivation of aluminum with water vapor with the separation of aluminum hydroxide from the alkylate and the separation of the residual fraction of C ₄ , distillation separation (sequentially) of ortho-TBP, 2,6-di-TBP, 2, 4-di-TBP and 2,4,6-tri-TBP. (The technological regulations of the installation for the synthesis of 2,6-di-tert-butyl-phenol. CJSC "Sterlitamak Petrochemical Plant", approved. 05.09.97 g).

 The amount of alkylation catalyst is 61-0.2 wt.% On the source phenol.

 The amount of the catalyst deactivating agent, water vapor, is 4-4.5 mol of water per 1 mol of catalyst.

 The method is carried out according to the following scheme (Fig. 1).

 In the alkylation reactor 1, phenol and a catalyst are fed from above (phenol: aluminum ratio, wt.% - 1: (0.001-0.002), a technical isobutylene-containing fraction containing 45-85 wt.% Isobutylene, butadiene-1,3, butylenes is fed from below.

 Alkylation proceeds under the above conditions for 8-10 hours at a molar ratio of isobutylene: phenol of 2.2: 1.0.

From the top of the alkylation reactor, a C ₄ fraction containing 2-5 wt.% Isobutylene is removed, from the bottom is an alkylate containing up to 85 wt.% 2,6-di-TBP, and ortho-TBP, 2,4- di-TBP, 2,4,6-tri-TBP.

Alkylate is sent to the debutanization column 2. Water vapor is supplied countercurrently, the residual amount of the C ₄ fraction is withdrawn from the top, and the alkylate and aluminum hydroxide separated from the bottom are removed from the bottom. The product is then sent to distillation column 3 to isolate ortho-TBP. From the bottom of column 3, an alkylate is removed containing 2,6-di-TBP, 2,4-di-TBP, 2,4,6-tri-TBP, phenol, which is sent to distillation column 4. From the top of column 4 at 102 ^o C and 10-15 mmHg the target product is removed - 2,6-di-TBP.

 The bottoms product of column 4 is sent to distillation column 5, from the top of which a product containing 2,4-di-TBP is discharged and sent for isomerization to the 2,4-di-TBP production unit. VAT product - 2,4-three-TBP is used as an oil stabilizer.

The method allows to obtain 2,6-di-TBP with a yield of up to 84 wt.%, Purity 98-99.6 wt.%, T ^o _melting - 35.5-36.5 ^o C.

 The quality of the obtained product meets the requirements of TU 38.103378-86 on 2,6-di-tert-butyl-phenol, intended for the production of 2,6-di-tertiary butylparacresol and other phenolic stabilizers.

 If it is necessary to improve the quality of the obtained 2,6-di-TBP, for example, for deliveries under contracts, which usually stipulate a higher degree of purity, either additional purification by known methods (for example, recrystallization) is required, or it is necessary to increase the performance of distillation equipment, reflux number of columns, which is associated with high energy costs and higher cost of the product.

In the resulting product with additional purification of 2,6-di-TBP content is 99,60-99,90 wt%, t ^o its _melting -. Not lower than 36,5 ^o C, crystals - white. (Addition pr. 1 to the contract 1180/14 / 008-93 dated 04/26/93 g).

 However, some uses of 2,6-di-TBP (pharmaceuticals, the synthesis of certain phenolic stabilizers, maintaining the stability of the product itself during long-term storage) require higher-quality 2,6-di-tert-butyl-phenol.

 The aim of the proposed invention is to improve the quality of 2,6-di-tert-butyl-phenol.

This goal is achieved by the fact that they use a method that includes alkylation of phenol with an isobutylene-containing fraction on a catalyst - aluminum dissolved in phenol at 90-110 ^o C and 6-10 ata, deactivation of the catalyst with separation of the C ₄ fraction, isolation of ortho-TBP, then 2, 6-di-TBP, purification by isolation by rectification of 2,6-di-TBP by cooling / heating in a special apparatus with the output of high-purity 2,6-di-TBP in the liquid phase, isolation of an additional amount of 2,6-di from the resulting impurity flows -TBF and distillation separation of these flows on 2,4-di-TBP and 2,4,6-tri-TBP.

Cooling of 2,6-di-TBP isolated by distillation is carried out at (35 ± 0,1) ^o C, heating at (36 ± 0,1) ^o C.

To remove high-purity 2,6-di-TBP, the product in the cooling / heating apparatus is heated to 50-55 ^o C. After cooling, a white crystalline 2,6-di-TBP is obtained with _melting t ^o = 39 ^o C and a basic substance content of 99, 99-100 wt.%.

 Impurity flows of 2,4-di-TBP and 2,4,6-tri-TBP containing 14-20 wt.% Of the amount of 2,6-di-TBP received for cooling / heating are sent for rectification by recycle to the isolation column 2 , 6-di-TBP or in parallel to it.

 For the successful implementation of the method, it is very important that the sequential cooling / heating ("sweating") procedures are carried out in strictly isothermal mode.

To reduce energy consumption, especially with a high content of impurities 2,4-di-TBP and 2,4,6-tri-TBP in the isolation procedure of 2,6-di-TBP (1.0-1.4 wt.%) Cooling procedure / heating can be carried out in two, three stages, increasing the cooling temperature at each stage by (0.5 ± 0.1) ^o C, and the heating temperature by (0.7 ±) 0.1) ^o C, leading to the final stage to the above temperatures - (35 ± 0.1) ^o C and (36.0 ± 0.1) ^o C, respectively.

 The essence of the proposed method is based on the discovery of the existence of fusible eutectics with a pronounced extremum of 2,6-di-tert-butylphenol with alkyl phenols-impurities.

So, if 2,6-di-TBP melts at 39 ^o C, and 2,4-di-TBP melts at 55 ^o C, then the authors found that a mixture containing 65 wt.% 2,6-di-TBP and 35 wt.% 2,4-di-TBP melts at 14.5 ^° C. (extreme) (FIG. 2).

 The presence of a pronounced eutectic by the authors is presumably due to the tendency of partially shielded phenols to form clathrate structures.

 The ability of 2,6-di-tert-butylphenol and 2,4-di-TBP and 2,4,6-tri-TBP to form eutectics was used by the authors to isolate the latter from 2,6-di-tert-butylphenol by "cooling" "/" sweating "(heating).

 The temperature regimes of the cooling / heating procedures of the purified 2,6-di-TBP for quantitative isolation from it up to 11.4% (total) of 2,4-di-TBP and 2,4,6-tri-TBP and were determined based on the detected "eutectic curve" when using artificially made mixtures of these alkyl phenols at various quantitative ratios.

The method is as follows. (Fig. 3, Fig. 4)
In the conditions of the prototype method, alkylation is carried out in the reactor 1, alkylate debutanization during destruction of the alkylation catalyst in debutanization column 2, the separation of ortho-TBP in the distillation column 3, the allocation of 2,6-di-TBP from the top of the distillation column 4, purification of the isolated 2.6 -di-TBP by cooling / heating in a vertical apparatus 5 in one to three steps at (35.0 ± 0.1) ^o C and (36.0 ± 0.1) ^o C, respectively, at the final stage of cleaning for 30 minutes at I stage and 30-40 minutes - on II. The purified 2,6-di-TBP after the stage of "sweating" (heating) is heated to 50-55 ^o C and in the liquid phase is removed as the target product.

The content of the basic substance in the product is 99.99 -100 wt.%, _Melting t ^o = 39.0 ^o C. When cooling, white crystals are formed.

 In order to isolate 2,6-di-TBP from impurity streams formed during cooling / heating, they are sent to distillation column 6 (Fig. 3) or recycle to distillation column 4 (Fig. 4).

 The total flows of impurities — still products of columns 4 and 6 — are sent for rectification to column 7 (Fig. 3) or column 6 (Fig. 4), where 2,4-di-TBP and 2,4,6-three are isolated from them -TBF.

 In the case of separation of 2,6-di-TBP from impurity streams in a parallel working rectification column 6, a product is obtained containing up to 98.5-99 wt.% 2,6-di-TBP and meeting the requirements of TU 38.103378-86 by 2.6 di-TBP for synthesis. In the case of directing the flows of impurities by recycle to the same rectification column 4, its additional amount, together with the main one, from the top of the column goes to the purification unit 5. Thus, by combining the rectification and purification by cooling / heating, the method allows to obtain a high-purity 2,6-di TBP with minimal loss of the target product. The following are examples of the practical implementation of the methods for producing 2,6-di-TBP.

Example 1 (prototype)
In the upper part of the alkylation reactor 1 (Fig. 1) serves 1025 g of phenol containing 1.0% dissolved aluminum, at a speed of 1 mol / h for 11 hours

Countercurrent with a speed of 4 mol / h serves technical fraction C ₄ containing, wt.%: Isobutylene - 50, butadiene - 1.0, butylene - the rest.

The alkylation temperature is 100 ^o C, the pressure is 7 ata.

From the top of reactor 1, a C ₄ fraction containing 2.8% isobutylene is removed.

 From the bottom - alkylate composition, wt.% Phenol - 0.20; ortho-TBP - 8.90; 2.6-di-TBP - 86.95; 2,4-di-TBP - 1.75; 2,4,6-tri-TBP - 2.21.

Alkylate is sent to debutanization column 2, its operating modes: t ^o _top - 114 ^o C, t ^o _cube - 116 ^o C, pressure - 2 ata.

 From the bottom of the column serves water vapor at the rate of 4.5 mol of water per 1 mol of catalyst.

From the top of the column, the residual C ₄ fraction, water, is removed.

Product composition (excluding phenol content), wt.%: Ortho-TBP - 8.90; 2,6-di-TBP - 87.15; 2,4-di-TBP - 1.75; 2,4,6-tri-TBP - 2.20, sent to distillation column 3 with a capacity of 40 practical plates (etc.), with a reflux ratio (fl.h.) - 5.0, t ^o _top - 96 ^o C, t ^o _cube - 180 ^o C, the pressure of the top of the column 10-15 mm RT.article

 Ortho-TBP is removed from the top of the column, and the product of the composition is from the bottom, wt.%: 2,6-di-TBP - 95.70; 2,4-di-TBP - 1.90; 2,4,6-tri-TBP - 2,40.

The product is sent to distillation column 4 with a capacity of 41 trans. T., With a reflux ratio of 2.3, t ^o _top - 102 ^o C, t ^o _cube - 188 ^o C, pressure 10-15 mm Hg

 2,6-di-TBP composition, wt.%: 2,6-di-TBP - 99.00; 2,4-di-TBP - 0.80; 2,4,6-tri-TBP - 0.20.

A mixture of alkyl phenols is withdrawn from the bottom of the column, which is sent for separation into a distillation column 5 with a productivity of 56 pr. (trellised), with fl.ch. 2,3, t ^o _top - 146 ^o C, t ^o _cube - 205 ^o C, pressure - 20 mm Hg

 A product containing 91.05% by weight of 2,4-di-TBP is discharged from the top of column 5.

 The product under industrial conditions is sent for isomerization in the department of production of 2,4-di-TBP.

 The bottom residue of column 5 contains 97.90 wt.% 2,4,6-tri-TBP and is used as an oil stabilizer.

Obtained 2,6-di-TBP in a yield of 83.90 wt.% Based on the starting base material with a content of 99.0 wt.%, T ^o _Melting = 36,5 ^o C. Crystals have a pale yellow color.

 The product meets the requirements of TU 38.103378-86 for 2,6-di-tert-butyl-phenol, intended for use in the synthesis of phenolic stabilizers.

 The content of the components of the product at each stage of its preparation are shown in table 1.

Example 2
In the conditions of example 1, phenol is alkylated with an isobutylene-containing fraction in alkylation reactor 1 (Fig. 3), the alkylate is deactivated in column 2, ortho-TBP is isolated in distillation column 3, and 2,6-di-TBP is isolated in distillation column 4.

 Get 2,6-di-TBP, containing, wt.%: 2,6-di-TBP - 99.0; 2,4-di-TBP - 0.80; 2,4,6-tri-TBP - 0.20.

The product is sent to a vertical apparatus 5, in which it is cleaned by cooling / cooling in two stages. The cooling temperature at the first stage is (34.5 ± 0.1) ^o C, the temperature at the stage of heating at the first stage is (35.3 ± 0.1) ^o C.

The cooling temperature in the second stage (35.0 ± 0.1) ^o C, heating - (36.0 ± 0.1) ^o C.

 The cooling time at each stage is 30 minutes, the heating time is 30-40 minutes, until the liquid phase stops.

 The impurities released during these procedures, referred to in Table 2 as the “2.4-fraction”, are sent to a distillation column 6 operating in column 4 mode.

The purified 2,6-di-TBP, referred to in Table 2 as the “2,6-fraction”, is heated to 50-55 ^° C. and withdrawn as the desired product in the liquid phase. The product yield is 87.50 wt.% From received for cleaning in the apparatus 5.

Base substance content in the product is 100 wt.%, T ^o = _{melting point} 39 ^o C, during cooling forms white crystals that do not change it even during prolonged storage.

 The composition of the flows of impurities ("2,4-fraction") and the product to be purified ("2,6-fraction") are shown in table 2.

 The “2.4-fractions” streams received in the distillation column 6 are separated with the release of 2,6-di-TBP from the top of the column and a mixture of 2,4-di-TBP, 2,4,6-tri-TBP as a bottoms product.

 The bottoms product of column 6, together with the bottoms product of column 4, is fed to distillation column 7 operating in column mode 5 of Example 1.

 Withdrawn from the top of column 6, 2,6-di-TBP has a composition, wt.%: 2,6-di-TBP - 98.90; 2,4-di-TBP - 0.40; 2,4,6-tri-TBP - 0.70.

 The product yield is 12.10 wt.% From received for cleaning in the apparatus 5.

 The product meets the requirements of TU 38.103378-86 and is used for the synthesis of alkyl phenols.

 When separating the bottom products of columns 4 and 6 in column 7, a distillate containing 86.10 wt.% 2,4-di-TBP and a bottoms product containing 95.90 wt. % 2,4,6-tri-TBP. The total yield of 2,6-di-TBP is 83.6 wt.% (Of which 73.4% is highly pure) based on the starting phenol.

 The composition of the product at all stages of obtaining 2,6-di-TBP are shown in table 3.

Example 3
In the conditions of example 1, alkylation is carried out by passing an isobutylene-containing fraction through 1010 g of phenol with 1.2 g of aluminum dissolved in it (Fig. 3).

 Get the alkylate composition, wt.%: Phenol - 0.15; ortho-TBP - 9.62; 2,6-di-TBP - 85.80; 2,4-di-TBP - 1.18; 2,4,6-tri-TBP - 3.25.

 Alkylate enters the debutanization column 2 for the destruction of the catalyst in the conditions of example 1.

The residual C ₄ fraction is removed from the top of the column, the product of the composition (without phenol) from the bottom, wt.%: Ortho-TBP - 9.62; 2,6-di-TBP - 85.96; 2,4-di-TBP - 1.18; 2,4,6-tri-TBP - 3.24.

 The product enters the rectification column 3, in which, under the conditions of Example 1, the ortho-TBP column is withdrawn from the top of the column, the product of the composition, wt.%: 2,6-di-TBP is 95.20; 2,4-di-TBP - 1.28; 2,4,6-tri-TBP - 3.52.

 The bottoms product of column 3 enters the distillation column 4 operating in the mode of Example 1. From the top of the column 2,6-di-TBP is removed, containing, wt.%: 2,6-di-TBP - 98.60; 2,4-di-TBP - 0.58; 2,4,6-tri-TBP - 0.82.

 From the bottom of the column 4 remove impurities entering the distillation column 7.

2,6-di-TBP enters the cooling / heating apparatus 5, in which it is purified from impurities of 2,4-di-TBP and 2,4,6-tri-TBP in three steps for 30 minutes at the cooling stage and 30 -40 minutes at the heating stage at each stage of cleaning. At the first stage of cleaning, the cooling temperature is (34.0 ± 0.1) ^o C, the heating temperature is (34.7 ± 0.1) ^o C, at the second stage is (34.5 ± 0.1) ^o C and ( 35.3 ± 0.1) ^o C and at stage III - (35.0 ± 0.1) ^o C and (36.0 ± 0.1) ^o C, respectively. The composition of the flows of impurities and the product to be purified during purification in apparatus 5 are shown in Table 4. After heating to 50-55 ^° C, 2,6-di-TBP is removed in the liquid phase as the target product. Obtain 2,6-di-TBP 100% purity with a yield of 79.30% of the purification unit 5.

The melting point of 2,6-di-TBP 39.0 ^o C, when cooled, forms white crystals.

 The flows of impurities released at each stage of cooling / heating are sent for rectification to column 6 under the conditions of Example 2.

 From the top of column 66, 2,6-di-TBP of the composition is removed, wt.%: 2,6-di-TBP - 98.80; 2,4-di-TBP - 0.45; 2,4,6-tri-TBP - 0.75.

 The impurities discharged from the bottom of column 6 together with the bottoms product of column 4 are sent to distillation column 7, in which, in the operation mode of column 5, as described in Example 1, they are separated into 2,4-di-TBP and 2,4,6-tri-TBP.

 The composition of the product at each stage of its preparation are shown in table 5.

Example 4
In the conditions of example 1, alkylation is carried out by passing the isobutylene-containing fraction of example 1 through 100 g of phenol with 0.12 g of aluminum dissolved in it.

 In the alkylation reactor 1 (Fig. 4), an alkylate of composition 5 wt.% Is obtained: phenol 0.20; ortho-TBP - 8.90; 2,6-di-TBP - 86.40; 2,4-di-TBP - 1.80; 2,4,6-tri-TBP - 2.70.

Alkylate is sent to debutanization column 2, from the top of which under the conditions of Example 1 the residual fraction C _{4 is} removed, from the bottom - the product of the composition, wt.%: Ortho-TBP - 8.90; 2,6-di-TBP - 86.60; 2,4-di-TBP - 1.80; 2,4,6-tri-TBP - 2.70.

 The product is sent to column 3 to isolate the ortho-TBP discharged from the top of the column. The process is carried out under the conditions of example 1.

 VAT product of the column 3 composition, wt.%: 2,6-di-TBP - 95.05; 2,4-di-TBP - 2.00; 2,4,6-tri-TBP - 2.95; sent to column 4.

 From the top of column 4, 2,6-di-TBP is isolated, wt.%: 2,6-di-TBP - 99.00; 2,4-di-TBP - 0.30; 2,4,6-tri-TBP - 0.70.

The isolated 2,6-di-TBP (with a yield of 85.84 wt.% Based on the starting phenol) has a _melting t ^o 36,8 ^o C.

2,6-di-TBP is sent to apparatus 5, in which the impurities are cleaned in one step by “cooling” at (35.0 ± 0.1) ^o C for 30 minutes, then by heating at (36.0 ± 0 , 1) ^o C for 30 minutes

Upon termination of the separation of the impurity stream ("2.4-fraction"), the 2,6-di-TBP in the solid phase is heated to 50-55 ^° C and removed as the target product with a basic substance content of 99.99 wt.% And t ^o _melting 39 ^o C.

 The output of high-purity 2,6-di-TBP is 91.5 wt.% From received for cleaning in the apparatus 5.

 The composition of the flows during cleaning by cooling / heating are shown in table 6.

 The flows of impurities from apparatus 5 (“2.4-fraction”) are recycled to column 4.

 The bottoms product of the column 4 is sent to the distillation column 6, operating in the mode of column 5 of example 1.

 The composition of the product at each stage of obtaining 2,6-di-TBP are shown in table 7.

 The implementation of the method of obtaining 2,6-di-TBP according to the scheme, providing for the recycling of the flow of impurities from apparatus 5 to the distillation column of 2,6-di-TBP 4 (Fig. 4) is technically simpler than using an additional distillation column 6 (Fig. 3 ), and can be implemented, if the margin of the column 4 allows the capacity to increase the load on it up to 10-20%. Both variants of purification of the impurity stream exclude the loss of 2,6-di-TBP at the stage of its separation, allowing up to 79.0 wt.% Of the product to be isolated in "ultra-pure" form, the rest of it can be returned by recycling or to isolate 2,6-di-TBP brand "for synthesis" according to TU 38.103378-86.

 When the content of rectified by rectification of 2,6-di-TBP impurities in an amount of 1.50 wt. % or more, the process of obtaining high-purity 2,6-di-TBP becomes multi-stage and energy-intensive. During the purification, the reverse process of “clogging” of the target product with impurities is observed. Perhaps the process requires practical refinement, but so far the option of cleaning the product with impurities in it in an amount of more than 1.4 wt.% Using the cooling / heating technique has not been practically implemented.

The cooling and heating temperatures of (35.0 ± 0.1) ^o C and (36.0 ± 0.1) ^o C at the final stage and the corresponding temperatures at the intermediate stages are determined based on the detected existence of a 2,6-di-TBP eutectic with "impurity" alkyl phenols and practical experiments using control mixtures.

When deviating from the indicated temperature conditions at each of the cooling / heating stages by more than 0.1 ^° C, the desired degree of purification of 2,6-di-TBP cannot be achieved.

Heating 2,6-di-TBP to 50-55 ^o C when it is separated from the cooling / heating apparatus is necessary and sufficient for its complete withdrawal in the liquid phase from the technological scheme.

 The compositions of the products at each stage of obtaining 2,6-di-TBP are determined chromatographically according to TU 38.103378-86.

The phenol used in the alkylation corresponds to GOST 23519-79, aluminum to GOST 11070-74, the isobutylene-containing fraction C ₄ corresponds to TU 38.303-05-31-92 per butylene-isobutylene fraction.

Sources of information
1. SU 1351562 A1, 11/15/1987.

 2. Zhuravleva E. I. Technology of confectionery production. M .: Food industry, 1968, p. 315 - 325.

Claims (2)

1. A method for producing 2,6-di-tert-butyl-phenol, comprising alkylating phenol with an isobutylene-containing fraction of C ₄ in the presence of an aluminum catalyst dissolved in phenol, deactivating the catalyst, isolating the residual fraction of C ₄ , sequentially isolating clearly rectified impurities of alkyl phenols: ortho tert-butyl-phenol, 2,4-di-tert-butyl-phenol, 2,4,6-tri-tert-butyl-phenol and the target product, characterized in that it is isolated by clear rectification of 2,6-di-tert -butyl-phenol is subjected to sequential cooling / heating at (35.0 ± 0.1) ^o C and (36.0 ± 0.1) ^o C, respectively, with the release of the subsequent heating of high-purity 2,6-di-tert-butyl-phenol, and the streams of the resulting impurities are directed to an additional allocation of 2,6-di-tert -butyl-phenol distillation. 2. The method of obtaining 2,6-di-tert-butyl-phenol according to claim 1, characterized in that the cooling / cooling cleaning is carried out in two, three steps, increasing the cooling temperature at each step (0.5 ± 0.1 ) ^o С, and the heating temperature by (0.7 ± 0.1) ^o С.

Images