JPH0419981B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing phenols, and more specifically, using benzene monocarboxylic compounds or their salts, esters, or anhydrides as raw materials, oxidizing them in a liquid phase in the presence of a copper compound, a manganese compound, and a rare earth compound. This invention relates to a method of continuously reacting by dividing into two stages of reaction and hydrolysis reaction. In a method for producing phenols, which are hydrolysis products of benzene monocarboxylic acid phenol esters, from benzene monocarboxylic acids or their salts, esters, or anhydrides through an oxidative decarboxylation reaction in the liquid phase, copper Methods of using a compound, or even a copper compound plus a magnesium compound, as a catalyst are conventionally known. Furthermore, in such a method, the so-called two-stage reaction method in which the oxidation reaction to produce phenol esters and the hydrolysis reaction of the produced esters are continuously carried out in separate reactors, It is said to be an energy-saving process that can significantly reduce the amount of water vapor used in the hydrolysis reaction compared to a single-stage reaction method in which both of the two steps are carried out simultaneously in the same reactor. However, when such a two-stage reaction method is applied to the above-mentioned conventionally known method for producing phenols, a large amount of high-boiling point products are produced as by-products, resulting in a low yield. Conventional problems include a decrease in the rate of phenol production over time and a decrease in the catalyst recovery rate. As a result of studies to solve the above-mentioned conventional problems, the present inventors have discovered that phenoxybenzoic acids in the above-mentioned so-called two-step reaction method can be treated by using a catalyst consisting of a copper compound, a manganese compound, and a rare earth compound. The present invention has been achieved by discovering that not only by-products such as hydroxybenzoic acids, but also tar components derived from these by-products can be suppressed, and the selectivity of phenol can be significantly increased. That is,
The gist of the present invention is to contact benzene monocarboxylic acids or their salts, esters, or anhydrides with a molecular oxygen-containing gas in the presence of a copper compound, a manganese compound, and a rare earth compound in a liquid phase to obtain a benzene monocarboxylic acid phenol ester. The method of producing phenols is characterized in that the produced esters are hydrolyzed by contacting with superheated steam in the presence of the copper compound, manganese compound and rare earth compound. The copper compounds, manganese compounds and rare earth compounds used in the method of the invention must be dissolved in the reaction mixture under the reaction conditions, and copper compounds typically include, for example, copper benzoate, cuprous oxide, cupric oxide, Oxides or carboxylates such as copper salicylate, copper carbonate, copper hydroxide, etc. are used, and as manganese compounds, carboxylates or oxides such as manganese benzoate, manganese oxide (), (), etc. are used. be done. Rare earth compounds include each compound from lanthanum (La) with atomic number 57 to lutetium (Lu) with atomic number 71 in the periodic table, especially lanthanum (La), cerium (Ce),
Praseodymium (Pr), neodymium (Nd), promethium (Pm) and samarium (Sm) compounds are preferred, and soluble compounds such as carboxylates such as benzoates and acetates, oxides, etc. or those that react under the reaction conditions Compounds that convert to compounds that are soluble in the mixture can be used. Further, these rare earth compounds can be used alone or as a mixture. The amount used for the reaction raw materials is 0.01 to 5% by weight, preferably 0.1 to 3% by weight, based on copper for the copper compound, 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on manganese for the manganese compound, and 0.1 to 5% by weight, preferably 0.1 to 5% by weight, for the manganese compound. is 0.01 to 10 for each rare earth metal.
% by weight, preferably 0.1-5% by weight. Benzoic acid or substituted benzoic acid is used as the benzene monocarboxylic acid, but if it has a substituent, at least one of both adjacent positions (both ortho positions) of the carboxyl group must be vacant. Examples of the substituent include alkyl groups and halogens that are inert to the oxidation behavior of copper. Specifically, o-toluic acid, m-toluic acid, p-toluic acid, m-chlorobenzoic acid, p-chlorobenzoic acid,
p-methoxybenzoic acid, p-phenylbenzoic acid, etc. are used. As the molecular oxygen-containing gas used in the method of the present invention, air is economically most preferable, but air enriched with oxygen, air diluted with nitrogen, or a mixture of oxygen and nitrogen in a desired ratio may also be used. It can be gas. As is well known, the action of oxygen-containing gas is to catalytically advance the oxidation, i.e., reaction, of cuprous benzoate to cupric benzoate, and is blown in either intermittently or continuously. . In the two-stage reaction method of the present invention, the first stage oxidation reaction is performed at a temperature of 180 to 30°C, preferably 200 to 250°C,
Under reaction pressure conditions of 0.1 to 10 atm, preferably 1 to 3 atm, a molecular oxygen-containing gas is added to the molten raw material and the catalyst dissolved therein charged in a stirred tank reactor or bubble column reactor, etc. This is done by blowing intermittently or continuously to bring the gas into liquid contact. The amount of molecular oxygen-containing gas blown is 1
0.01/hr (NTP) in terms of oxygen gas per mmol
~100/hr (NTP), preferably 0.1/hr
(NTP) ~ 20/hr (NTP). The reaction time varies depending on conditions such as the amount of catalyst used, reaction temperature, pressure, etc., but is preferably about 0.1 to 5 hours. Second
The hydrolysis reaction in the second stage is carried out under the same or slightly milder conditions as the oxidation reaction in the first stage in terms of temperature, pressure, and reaction type. The amount of superheated steam injected is 0.01g to 100g/hr per mmol of copper,
Preferably it is 0.1 g/hr to 30 g/hr. In addition,
It is preferable to blow in oxygen-containing gas at the same time as superheated steam, and the blowing amount is 0.1ml/oxygen gas equivalent.
hr(NTP)~10/hr(NTP), preferably 0.01
〜/hr(NTP)〜1/hr(NTP). The reaction time varies depending on conditions such as the amount of catalyst used, reaction temperature, and pressure, but is preferably about 0.1 to 5 hours.
Furthermore, in both the first-stage oxidation and second-stage hydrolysis reactions, an inert solvent can be used if desired. Phenols obtained by the two-stage reaction method of the present invention are generally recovered by distillation. Further, unreacted benzene monocarboxylic acids are separated and recovered from the catalyst and reaction products by a known method such as distillation, and reused as a reaction raw material. Like unreacted raw materials, the catalyst is recovered and reused by a known separation method. Catalyst that is unavoidably contained in high-boiling products and separated from the system is replenished. According to the manufacturing method of the present invention detailed above, the following remarkable effects not seen in conventionally known methods are observed. (1) The catalyst used in the present invention can selectively produce phenols in particular. (2) Conversely, diphenyl ethers and high boiling point products,
That is, the amount of tar components produced is small, and therefore the reduction in the rate of phenol production is extremely small. (3) Since the amount of tar is small, it is easy to separate the catalyst and tar, and the loss of the catalyst is small, making it economical. Although the role of each component of the catalyst in the present invention (hereinafter referred to as the present catalyst) is not clear at present, it is inferred as follows. In other words, the main catalyst of this catalyst system is a copper compound, which exists as copper benzene monocarboxylate () during the reaction.
Manganese compounds and rare earth compounds are thought to have auxiliary effects. For example, when a simple manganese compound is added to the copper compound as the main catalyst, the rate of phenol production increases at the early stage of the reaction, but gradually decreases and diphenyl ethers are produced. On the other hand, when a rare earth compound is added in addition to the manganese compound, the formation of diphenyl ethers is not observed, and phenols are constantly formed over a long period of time. The reason for this is that the rare earth compound prevents the overoxidation reaction of manganese and maintains the preferred valence state of manganese, probably divalent or trivalent, so that the copper-manganese-rare earth This is thought to be due to the formation of a stable reaction state. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Rotary stirring type with 300ml capacity baffle plates (3 pieces of 5mm x 40mm) (with a semicircular Teflon stirring plate with a diameter of 20mmφ)
134.7 g of benzoic acid in a four-neck round-bottom glass reactor.
(1103.2mmOl), basic copper carbonate ( _CuCO3・Cu
(OH) ₂ H ₂ O) 1.61g (6.4mmOl), manganese oxide (MnO) 1.82g (25.6mmOl), and lanthanum oxide (La ₂ O ₃ ) 4.17g (12.8mmOl) were charged, and a gas inlet was added to the mixture. and a distillation tube were connected, and the reactor was heated by a mantle furnace. After the reaction temperature reached 235°C, heated air was blown into the molten benzoic acid from the bottom of the reactor at a flow rate of 30/hr (NTP).
The stage oxidation reaction was started. The rotation speed of the stirring plate is
It was hot at 1300rpm. Gas components and low-boiling liquid components including phenols are distilled and separated in a distillation tube (a Wiglow tube with an inner diameter of 30 mm and a height of 300 mm) connected to the reactor, and the liquid components are collected in a liquid trap. The temperature was controlled at 110-130℃. The reaction was stopped after 100 minutes, and 0.788 g of the reactor liquid and the distillate collected in the liquid trap were taken out. Each sample was diluted and dissolved in 1,4-dioxane and analyzed by liquid chromatography. As a result, the phenol (hereinafter abbreviated as PHL) in the reactor was
0.4wt%, benzoic acid (hereinafter abbreviated as BA) is
53.3wt% and phenyl benzoate (hereinafter referred to as PHBA)
It is abbreviated as ) was 37.3wt%. Also, from the distillate, PHL6.7g (71.2mmOl), BA1.51g
(12.3 mmOl) and 0.04 g (0.2 mmOl) of PHBA were obtained. After completing the first stage oxidation reaction, 0.3/hr (NTP)
The temperature was lowered while blowing in air, and after the hydrolysis reaction temperature reached 200℃, the steamed water was heated to 30℃
g/hr and heated air 0.3/hr (NTP)
The second stage hydrolysis reaction was started by blowing from the bottom of the reactor at various flow rates. The rotation speed of the stirring plate is
It is 1300rpm. The reaction was stopped after 120 minutes. The reactor residual liquid and effluent were each diluted and dissolved with 1,4-dioxane to make a fixed amount of 500 ml, and a portion of 10 ml was added.
PHL by liquid chromatography.
BA and PHBA were quantified. In addition, quantitative analysis of medium-boiling point products and measurement of the amount of tar were performed on the reactor residual liquid. The method for analyzing medium boiling point products is to remove 10 ml from the above diluted 1,4-dioxane solution,
After distilling off 1,4-dioxane at a pot temperature of 110 to 130°C, return it to room temperature, and add 20% dimethyl ether to this.
ml and 20 ml of 2N hydrochloric acid were added and a thorough vibration extraction operation was performed, the aqueous layer was extracted, and the ether layer was methyl esterified by the diazomethane method and then quantified by gas chromatography. Medium boiling point products include salicylic acid (hereinafter abbreviated as SA),
m-, and p-hydroxybenzoic acid (hereinafter referred to as
Abbreviated as HOBA. ), o-, m-, and p-phenoxybenzoic acid (hereinafter abbreviated as POBA),
Examples include m- and p-benzoyloxybenzoic acid (hereinafter abbreviated as BOBA) and diphenyl ether (hereinafter abbreviated as DPE), and the correction coefficients for each of these were determined and quantified. Further, the amount of tar was determined by the following method. That is,
Take out 100ml of the above diluted 1,4-dioxane solution and add 1,4-dioxane to the pot at a temperature of 110 to 130°C.
After distillation, the temperature was returned to room temperature, 200 ml of diethyl ether and 200 ml of 2N hydrochloric acid were added, and after thorough vibration extraction, the aqueous layer was extracted.
ml was added and sufficiently vibrated to extract acidic substances such as benzoic acid. After repeating this operation once more, the ether layer was filtered, and the filtrate remaining on the funnel was thoroughly washed with diethyl ether, and after drying,
The weight of the filter dregs was measured to determine the amount of tar. As a result of the above analysis, it was found that the distillate contained
PHL11.09g (117.8mmOl) and BA0.73g
(6.0mmOl), PHL5.29g in the reactor residual liquid
(56.2mmOl), BA81.52g (667.7mmOl),
PHBA14.3g (72.4mmOl), m-HOBA0.3g
(2.2mmOl), o-POBA0.6g (2.8mmOl), m-
and P-BOBA 0.35g (1.4mmOl), and tar 0.29g (PHL equivalent 3.1mmOl) were observed. Benzoic acid conversion rate (mol%), phenol, total phenol (produced phenol + produced phenyl benzoate), selectivity of medium-boiling products and tar (mol%), and φ balance (benzene ring balance) (mol%) The details are summarized in Table 1 below. Example 2 Cerium acetate (Ce) was used instead of lanthanum oxide.
The same procedure as in Example 1 was carried out except that 8.58 g (25.6 mmOl) of (CH ₃ COO) _{3.H 2} O) was used. The results are summarized in Table 1 below. Example 3 Industrial didymium (La ₂ O ₃ 56.3%, Nd ₂ O ₃ 33.0%, Pr ₆ O ₁₁ 8.8%,
The same procedure as in Example 1 was carried out except that 4.17 g of Sm ₂ O ₃ (1.5%) was used. The results are summarized in Table 1 below. Comparative Example 1 The same procedure as in Example 1 was carried out except that 2.06 g (51.2 mmOl) of magnesium oxide (MgO) was added as a catalyst in addition to basic copper carbonate. The results are summarized and compared in Table 1 below.

【table】

[Table] As is clear from the results in Table 1 above, the method of the present invention has an extremely high selectivity for all phenols and an extremely high selectivity for tar compared to the conventional method using a Cu-Mg catalyst. It's much better at low points.

Claims (1)

[Claims] 1 Benzene monocarboxylic acids or their salts, esters, or anhydrides are brought into contact with a molecular oxygen-containing gas in the presence of a copper compound, a manganese compound, and a rare earth compound in a liquid phase to mainly produce benzene monocarboxylic acid phenol esters. A method for producing phenols, which comprises: then hydrolyzing the produced esters by contacting them with superheated steam in the presence of the copper compound, manganese compound, and rare earth compound.