Method for preparing hydroxyaromatic compounds

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing hydroxyaromatic compounds by oxidation of aromatic compounds with nitrous oxide in gaseous phase in the presence of zeolites. Method is realized by interaction of aromatic compounds of the formula (I): Ar-Rn wherein Ar means benzene or naphthalene; R means bromine, chlorine, fluorine atom, -NO2, -CN, -NH2, hydroxy-group, alkyl with 1-6 carbon atoms or phenyl; n = 0, 1 or 2 with nitrous oxide in gaseous phase in the presence of zeolites taken among the following order: pentasil, ferrierite and zeolite-β. Zeolite crystallites size is less 100 nm that is calcined before using at temperature from 500°C to 1350°C for 0.5-18 h. Before the calcination process zeolite is modified preferably by precipitation of silane or borane. Method provides realization of the process for a single step with high yield of the end compound and minimal formation of by-side substances.

EFFECT: improved preparing method.

11 cl, 3 tbl, 13 ex

 

This invention concerns a method of obtaining hydroxyaromatic compounds by oxidation of aromatic compounds nitrous oxide (N2O) in the gas phase in the presence of nanocrystalline zeolites.

Hydroxyaromatic compounds are valuable intermediates in organic chemistry. They are used in the synthesis of numerous intermediate and final products. Hydroxybenzene are used in photography, as well as antioxidants and stabilizers for plastics. Phenol process, for example, phenolic resins, caprolactam, bisphenol a, adipic acid or ALKYLPHENOLS. The cresol is used for the manufacture of antioxidants, herbicides, insecticides, dyes and fragrances and flavouring substances. Among the three isomers of cresol p-cresol from an economic point of view is the most interesting METHYLPHENOL as p-cresol used in the synthesis of plastics, lubricants, medicines, food additives (Nutrazeutika), as well as for the manufacture of flavorings. But it is mostly used for the production of BHT (2,6-di-tert-butyl-4-hydroxy-toluene), a known anti-aging and antioxidant.

The number of known ways to get hydroxyaromatic compounds. For example, currently, there are 4 important technical is their method of synthesis cresol, based on 2 synthesis pathway: either hydroxylation of toluene or alkylation of phenol.

Getting cresol alkaline fusion toluene sulfonate is carried out in two reaction stages. First, toluene sulfurous concentrated sulfuric acid formed at this sulfoxylate the mixture is neutralized with sodium sulfite or sodium hydroxide solution and then alloy with sodium hydroxide at about 300°C. Then an aqueous solution of the melt is acidified with sulfur dioxide or sulfuric acid, which formed as a result of the cresol. Typically, a mixture is formed with 6-12% o-cresol, 6-12% m-cresol and 80-85% of p-cresol. The latter can be separated by fractional crystallization. However, this process has the disadvantage that produce large quantities of sodium sulfite, which must be disposed.

Hydrolysis chlorotoluene is used primarily for the production of m-cresol. In the first stage, toluene glorious in the presence of ferric chloride and subdiploid sulfur, thereby forming a mixture of o-/p-toluene in the ratio of 1:1. If immediately thereafter to carry out the hydrolysis of alkaline sodium bicarbonate is formed, o-, m - and p-cresol in the ratio 1:2:1. After rectification receive on-kretlow faction and difficult separable mixture of m - and p-cresol in the ratio of 3:1. Therefore, in most cases the first share from the career chlorotoluene and only then carry out the hydrolysis. Of o-chlorotoluene after hydrolysis and subsequent distillation can be obtained pure o - and m-cresol, p-chlorotoluene still formed a mixture of m - and p-cresol 1:1. The disadvantage of this process, along with a slight release of p-cresol is the presence of side products, such as tolyl-Cresols and calilove esters.

When the three-stage decomposition of cumene zimola in the first stage, toluene alkiliruya-propene, forming a mixture of isomers of zimola. Then it is oxidized by oxygen to hydroperoxides of zimola that at the third stage are split under the action of acid for m-/p-cresol in the ratio 3:2 and acetone. Additionally, there are a lot of by-products. In this process achieves the following distribution of isomers 3% o-zimola, 64% m-zimola and 33% p-zimola. Low the outputs are determined mainly minor oxidation rate zimola, allowing only 20% oxidation at an acceptable formation of by-products. This is followed by the high costs of separation and recycling of wastewater. The formation of acetone equivalent to cresol amounts advanced greatly affects the efficiency of the process.

Synthesis cresol by methylation of phenol is carried out in gas phase and in the liquid phase. Compared with toluene phenol is a relatively expensive educt, prevadid very little or absolutely no outlet p-cresol. The following disadvantages of a single-stage alkylation of phenol are very high costs of separation of the mixture of reaction products, as its components have very similar boiling point. In addition, the additional high cost of investment in korozionnostoykiye device significantly degrade the effectiveness of the process.

Because technically implemented at the moment, the process yield of Cresols with adverse isomeric distribution of p-cresol and only multi-methods allow you to move the process in the direction of increasing the output of p-cresol, i.e. the need for single-stage selective synthesis of p-cresol. Thus heterogeneously catalyzed selective oxidation of toluene nitrogen oxide in the gas phase is an interesting alternative. The use of nitrous oxide as an oxidizer is a new way of synthesis, which leads to immediate receipt of phenol from benzene, the search which began in the early 80-ies. When this interaction is catalyzed by the zeolite.

In the German patent application DE AND 19634406 describes the interaction of aromatic compounds with nitrogen oxide to the corresponding hydroxy-aromatic compounds, and a catalyst for use zeolite type pentasil or β-type, to which were subjected to preliminary hydrothermal treatment with water vapor. When the hydroxylation of toluene selectivity in respect of cresol is 27%, with 24% of the transformation. The disadvantage of this process is that the proportion of p-cresol in krasilnoj faction is only 16%.

In U.S. patent US-A 5110995 described method hydroxylation of toluene nitrogen oxide in the presence of iron-containing zeolite, which takes place in a narrow region of the temperature range from 275 to 450°C. When the conversion of 48% selectivity for cresol is 20%. The proportion of p-cresol in krasilnoj fraction is 33%.

In European patent application EP-A 889081 describes a method for hydroxyaromatic compounds, which is conducted in the presence of zeolites, held a special two-stage calcination. When the hydroxylation of toluene conversion is 25% and the selectivity for cresol 22%. The isomer distribution is not given.

There is therefore a need to develop a method hydroxylation of toluene nitrous oxide with high selectivity and high yield of p-cresol.

This task is achieved by the described method of obtaining hydroxyaromatic compounds by oxidation of aromatic compounds of the formula (I)

where

Ar denotes a benzene or naphthalene,

R means bromine, chlorine, fluorine, NO2, CN, NH2hydroxy, alkyl with 1-6 carbon atoms or phenyl and

n stands for zero, 1 or 2,

nitrous oxide in the gas phase in the presence of zeolites selected from a number of pentasil, ferrierite and zeolite-β, which is characterized by the fact that the zeolite has a crystallite size less than 100 nm, and it first before using calicivirus at a temperature of from 500 to 1350°C.

In accordance with the invention, in the method using an aromatic compound of the formula (I). When it comes to optionally substituted benzene or an optionally substituted naphthalene. Preferably use benzene, alkyl benzene with 1-6 carbon atoms in the alkyl part, chlorobenzene, torbenson, benzonitrile, naphthalene or biphenyl. Particularly preferably used alkylbenzene with 1-6 carbon atoms in the alkyl part, very particularly preferably toluene.

Below are described in more detail used in accordance with the invention, the zeolites. Zeolites are crystalline aluminosilicates which have a highly ordered structure with a rigid three-dimensional mesh of tetrahedra SiO4and AlO4linked by common oxygen atoms. Electrovalent aluminium-containing tetrahedra is balanced by the inclusion in the crystal of cations, for example cations of the first, second or third main group of the Periodic system of elements is s or hydrogen. It is possible to cation exchange. The spaces between the tetrahedra are occupied by water molecules, dehydration drying, and accordingly calicivirus.

In the method of the present invention using nanocrystalline zeolites from a number of pentasil, β-zeolite and ferrierite having a crystal size less than 100 nm.

Zeolite-β has as a structural unit constructed of SiO4tetrahedra 4-, 5 - and 6-membered rings, which form a three-dimensional structure. These three-dimensional frameworks built form of the 12-ring channels, which are in two spatial directions are straight, and the third direction are on the sine wave. The material forms ellipsoidea pores having a size of about 5.5×7,6 E.

Further, in the method of the present invention use zeolites of type pentasil. They have as a structural unit constructed of SiO4tetrahedra 5-membered ring. These zeolites are characterized by a high ratio Si/Al, and a pore size of about 5,3×5,6 Å and 5.1×5,5 Å, which is lower than that of zeolite-βand are in the field of values of a molecule of cresol. The preferred zeolite type pentasil is ZSM-5.

Ferrierite has structural units constructed of SiO4tetrahedra 8 - and 10-membered rings. The channels are elipsoidal, the size of the in-plane [001] is the example is about 4,2× 5,5 Å (10-membered ring), in the plane [010] is about 4.8×to 3.5 Å (8-membered rings).

For the method of the present invention, instead of aluminum and silicon in the zeolite lattice can be embedded with one or more other elements. Thus, the aluminum may be replaced by elements such as boron, gallium, iron, chromium, vanadium, arsenic, antimony, bismuth, as beryllium and mixtures thereof, and the silicon in such a tetravalent element such as germanium, titanium, zirconium, hafnium or mixtures thereof.

The above-mentioned zeolites in the present invention preferably use the azide form. Azide forms of zeolites produced mainly by exchange of cations for ammonium ions or exchange with mineral acid. You can also use partial azides zeolites, in which part of the hydrogen ions are replaced by cations of the first, second and third main group of the Periodic system of elements, as well as side groups Ia, IIa, IVa, Va, VIa, VIIa and VIIIa. Preferred cations are the cations of the elements lithium, sodium, potassium, rubidium, magnesium, calcium, barium, iron, cobalt, vanadium, zinc, chromium, manganese, Nickel, palladium and copper are particularly preferred cations of the elements lithium, potassium, rubidium, magnesium, calcium, barium, iron, cobalt, vanadium, Nickel and zinc. Mainly in the method of the present invention using zeolites, in the which from 50 to 100%, particularly preferably from 80 to 100%of the originally present cations are replaced by hydrogen ions.

Used in the method of the present invention, the zeolites generally have a ratio Si/Al from 15 to 400, preferably from 20 to 200 and particularly preferably from 25 to 180.

Getting used in the method of the present invention, zeolites having a crystallite size less than 100 nm, can be realized, for example, as described in the international patent application WO 93/08124 or in European patent application EP-A 178687. The crystallite size used in the method of the present invention zeolites is mainly 20-100 nm, particularly preferably 30-40 nm.

Used in the method of the present invention, the zeolites before using calicivirus. The calcination is carried out at a temperature of from 500 to 1350°C, preferably at from 500 to 1250°C, particularly preferably at a temperature of from 700 to 1200°C. When the calcination are mostly within 0.5 to 18 hours, preferably 1-10 hours. When the calcination will take place mainly in the atmosphere of nitrogen or a nitrogen/oxygen atmosphere with a portion of the oxygen mainly from 1 to 50 vol.%, particularly preferably from 10 to 30 vol.%, or in the air. Very particularly preferred zeolites, whether at from 700 to 1200°C for 1 d is 10 hours in air atmosphere.

In the method of the present invention, the zeolites can be used in the form of powders, granules, particles or in the form of extrudates. Hereinafter, used in the method of the present invention, the zeolite can be incorporated into an inorganic matrix, which is preferably inert. Used inorganic matrix materials are, for example, conventional materials-media, such as silica, aluminum oxide, zirconium oxide, silicates, synthetic porous materials or clay. Preferably use diazidnyi materials-media.

In the method of the present invention the flow rate of the catalyst with the aromatic compound, expressed through the WHSV (Weight-Hourly-Space-Velocity - mass hourly velocity of the gas, kg/h of aromatic compound per kg of catalyst), is mainly of 0.1-10 h-1particularly preferably 0.2 to 5 h-1, very particularly preferably 0.5 to 3 h-1.

In a preferred form of execution of the method of the present invention used zeolites before calcination modify silanes or boron. When this silane or borane mainly precipitated on the used zeolite by the method of chemical vapor deposition (CVD chemical vapour deposition). Mainly as silanes use disilane, alkylsilane, as, for example, methylsilane, or atysian, and silane. As Baranov mostly use DIBORANE or borane. The deposition is carried out mainly at a temperature of 150-300°S, especially preferably at 200-270°C. Mostly partial pressure of the silane/borane determine from 1 to 1000 mbar, particularly preferably from 350 to 650 mbar. The time of deposition is mainly from 30 to 300 minutes, particularly preferably from 150 to 250 minutes.

In the following a preferred form of execution of the method of the present invention used zeolites before calcination modify alkoxysilane. In this case, the deposition of alkoxysilanes occurs in the gas phase, mainly in the same reactor, which is used in the method of the present invention. Mainly use alkoxysilane with 1-4 carbon atoms, such as, for example, tetramethoxysilane or tetraethoxysilane, particularly preferably tetraethoxysilane. Precipitation is predominantly carried out at a temperature of 100-400°S, especially preferably at 150-250°C. the Partial pressure of alkoxysilane establish mainly from 1 to 500 mbar, particularly preferably from 10 to 100 mbar, deposition time is preferably from 5 to 180 min, particularly preferably from 10 to 80 minutes Deposition consists mainly of a few cycles, mainly carried out from 5 to 25 cycles of deposition. Special is preferably about precipitation thus, to precipitate tetraethoxysilane with a partial pressure of from 30 to 60 mbar for 10-20 cycles of deposition at 180-220°and time for the cycle from 20 to 40 minutes After each deposition conduct subsequent thermal treatment of the zeolite mainly in the atmosphere of oxygen, an atmosphere of oxygen/air or in air at a temperature of 200-600°C.

The reaction temperature in the method of the present invention is mainly 300-560°C, preferably 350-540°S, very particularly preferably at 400 to 500°C.

Working pressure is mainly between 0.1 and 15 bar, particularly preferably between 0.2 and 6 bar, particularly preferably between 0.5 and 2 bar.

The molar ratio of aromatic compounds: nitrous oxide is mainly from 12:1 to 1:10, particularly preferably from 10:1 to 1:5, particularly preferably from 8:1 to 1:4.

The reaction is carried out usually in the gas phase.

The reaction of aromatic compounds, and calcining the zeolite and, if necessary, the modification of zeolites by alkoxysilane can be done for this invention in the usual designed for heterogeneous catalysis reactor, such as reactor with a fixed catalyst or reactor with a fluidized bed.

As a reactor with a fixed catalyst can use isometsa, for example, loop reactors, reactors with lattice and tubular reactors. If the reaction is carried out in a reactor with a fixed catalyst, the use of zeolite catalysts with an average particle diameter of preferably 500-2000 microns.

In the reactor with a fluidized bed, also known as a fluidized bed reactor has a reaction space in which the scattered granular solid material is loosened passing from the bottom of the gas and is in limbo. This greatly distended gas-permeable layer is called boiling or fluidized bed. He has a behavior similar to a boiling liquid with strong stirring. In the way fluidized bed individual components may be filed in the boiling layer in a mixture or separately through the pre-evaporator or directly into the fluidized bed. Thus the most appropriate use of the zeolite catalyst in extruded form with an average particle diameter 80-250 μm.

Examples

Example 1

Preparation of catalyst

We used the following catalysts:

A: Zeolite catalyst, type N [Al] ZSM-5, the ratio of Si/Al: 15

In: Zeolite catalyst, type N [Al] ZSM-5, the ratio of Si/Al: 28

From: Zeolite catalyst, type N [Al] ZSM, the ratio Si/Al: 113

D: Zeolite catalyst, type Nβratio Si/Al: 75

E: Zeolite cat is the lyst type N [Al] ZSM-5, the ratio of Si/Al: 25, crystallite size: 1000-3000 nm

F: Zeolite catalyst, type N [Al] ZSM-5, the ratio of Si/Al: 26, crystallite size: 30-40 nm

Zeolites without binder pressed into tablets with a diameter of 0.5 cm, then crushed to a particle size of 1.0-1.4 mm and fractionary.

Examples 2 to 4

In examples 2-4, respectively, using 2 g of the above catalyst for the implementation of the interaction of toluene with nitrogen oxide in the reactor with a fixed catalyst at 450°C. the Length of the filling is 20-30 cm Mass hourly gas velocity (WHSV) choose a 2.5 hour-1(g toluene / h and g of catalyst). Toluene and nitrous oxide are used in a molar ratio of 1:3. All the samples were taken after 32 min TOS (continuous operation) and analyzed by gas chromatography, using a CP-Chirasil-Dex® column. The results are shown in table 1.

Table 1
ExampleThe crystallite size [nm]ZeoliteThe conversion of toluene [%]Selectivity relative cresol [%]The proportion of p-cresol [%]
220-100Anda 4.9
320-100In9,6 11,08,9
420-1003,030,016,5

Examples 5-7

Examples 5-7 carried out analogously to examples 2-4, and catalysts b, E, and F before the reaction for 2 hours was caliciviral at 900°s on the air. The results are shown in table 2.

Table 2
ExampleThe crystallite size [nm]ZeoliteThe conversion of toluene [%]Selectivity relative cresol [%]The proportion of p-cresol [%]
51000-3000E4,521,034,0
620-100In14,033,023,0
730-40F18,739,035,0

Examples 8-11

Examples 8-11 carried out analogously to examples 2-4, and catalysts before reaction of 2 hours was caliciviral at 1000°s on the air. The results are shown in table 3.

Table 3
ExampleThe crystallite size [nm]ZeoliteThe degree of conversion of tolua the [%] Selectivity relative cresol [%]The proportion of p-cresol [%]
820-100And10,023,917,8
920-100Inthe 15.629,329,1
1020-10012,3to 58.1to 45.4
1120-100D11,063,046,0

Example 12

The catalyst is treated for 3 hours at 200°C, 200 min silane (partial pressure of 500 mbar) and then 2 hours calicivirus at 1000°s on the air. The crystallite size is 20-100 nm. The interaction of toluene with nitrogen oxide carried out analogously to examples 2-4. The conversion of toluene is 16,0%, the selectivity of 47.0% and the proportion of p-cresol to 44.0%.

Example 13

The catalyst With calicivirus 2 hours at 1100°With air and then for 14 cycles for 30 min at 200°treated with tetraethoxysilane (partial pressure of 40 mbar). After each cycle, the catalyst for 2 hours thermally treated at 500°s on the air. The crystallite size is 20-100 nm. The interaction of toluene with nitrogen oxide carried out analogously to examples 2-4. The conversion of toluene is 6.0%, the selectivity of 60% and the proportion of p-cresol to 57.0%.

1. The method of obtaining hydroxyaromatic compounds by interaction of aromatic compounds of the formula (I)

where Ar denotes a benzene or naphthalene;

R means bromine, chlorine, fluorine, NO2, CN, NH2, hydroxy, alkyl with 1-6 carbon atoms or phenyl and

n means 0, 1 or 2,

with nitrous oxide in the gas phase in the presence of zeolites selected from a number of pentasil, ferrierite and zeolite-β, characterized in that the use of zeolite with crystallite size less than 100 nm, pre-calcined at a temperature of from 500 to 1350°C.

2. The method according to claim 1, characterized in that the use of alkyl benzene with 1-6 carbon atoms in the alkyl part by obtaining a product with a high share of p-isomers.

3. The method according to claim 1, characterized in that the use of toluene with getting cresol with the increased share of p-Cresols.

4. The method according to one of claims 1 to 3, characterized in that the use of zeolite in the form of azide.

5. The method according to claim 1, characterized in that the use of zeolite, pre-calcined for 0.5-18 hours

6. The method according to claim 5, characterized in that the use of zeolite, pre-calcinated in a nitrogen atmosphere, a mixture of oxygen and nitrogen or air.

7. The method according to claim 1, characterized in that the use of zeolite having a crystallite size of 20 to 100 nm.

8. The method according to claim 1, characterized in that the use of zeolite having a crystallite size of 30-40 nm.

9. The method according to claim 1, characterized in that the zeolite used H - [Al]ZSM-5 or H-β.

10. The method according to claim 1, characterized in that the use of zeolite modified by deposition of silane or borane before calcination.

11. The method according to claim 1, characterized in that the use of zeolite modified by deposition of alkoxysilane after calcination.



 

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< / BR>
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