DE1922607C - Process for the preparation of 2,6-dialkylphenols by reacting cyclohexanone with aldehydes - Google Patents

Description

The invention relates to a process for the preparation of 2,6-dialkylphenols by reacting cyclohexanone with aldehydes, especially formaldehyde or acetaldehyde at an elevated temperature in the Vapor phase in the presence of a special catalyst.

2,6-Dialkylphenols have been found in the plastics field great importance as starting materials for new synthetic resins, for example polyphenylene oxide, attained.

Numerous processes for the preparation of 2,6-dialkylphenols are known, e.g. B. a procedure for methylation of phenol disclosed in Japanese Patent Publications 6894/1967 and 8255/1968 is described, one in Dutch Patent Publication 290 847 and Japanese Patent Publication 7450/1967 described method for debutylation of 2,6-dimethyl-4-tert-butylphenol, and a process for the vapor phase reaction of Cyclohexanone with an aldehyde that is described in Swiss patent specification 445 518, the French U.S. Patent 1,377,943, Belgian Patent 641,864 and U.S. Patent 3,280,201 becomes known. However, the yields achieved here are quite low. You are in the Practice mostly below 50%.

It was now after extensive studies on the vapor phase reaction of cyclohexanone with formaldehyde or acetaldehyde surprisingly found that a compound of metals Group I a of the Periodic Table of the Elements is more effective as a catalyst than all catalysts known to date for the production of 2,6-dialkylphenols.

It was also found that the yield and selectivity of the formation of 2,6-dialkylphenols is markedly enlarged when a compound of the metals of groups IVa and Va of the periodic table the elements is used as a promoter together with the catalyst according to the invention.

Accordingly, the invention is a process for the preparation of 2,6-dialkyl phenols by reaction of cyclohexanone with aldehydes at elevated temperature in the gas phase in the presence of a catalyst, which is characterized in that the reaction is carried out at a temperature of 150 to 85O C ¹ , preferably 250 to 650 ^° C., in the presence of a compound of a metal of the first main group of the Periodic Table of the Elements applied to a support as a catalyst, which is preferably also a compound of a metal of the FV. or V, main group of the Periodic Table of the Elements, as a promoter.

The compounds of metals of Group Ia used as a catalyst according to the invention of the periodic table of the elements are carbonates, bicarbonates, nitrates and oxides of the metals lithium, Sodium, potassium, rubidium and cesium and compounds of the general formula MOX, in which M a metal of Group I a of the Periodic Table of the Elements and X is a hydrogen atom, a lower one Denotes alkyl radical, aryl radical or acyl radical.

Examples of the compounds of metals used according to the invention as a catalyst Group la of the periodic table are lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, Cesium carbonate, Lilhiumbiearbonnt, Na-Iriumbicarbonat, Potassium bicarbonate, rubidium carbonate, cesium bicarbonate, lithium nitrate, sodium nitrate, Potassium nitrate, rubidium nitrate, cesium nitrate, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, Cesium oxide, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, Lithium methylate, sodium methylate, potassium methylate, lithium phenolate, sodium phenolute, Potassium phenolate, sodium formate, lithium acetate, potassium acetate, sodium acetylacetonate, nirium salt of Ethyl acetic acid.

The preferred amount of the catalyst is in the range of 0.01 to 10 g based on 1 g of the per Hour flowing through amount of the starting material, and the catalyst compounds mentioned can can be used alone or as a mixture of two or more compounds.

The compounds of metals used as a promoter for the process according to the invention Group IVa and Va of the Periodic Table of the Elements are carbonates, oxides, formates, acetates, Oxalates, halides or nitrates of metals from group IVa and Va of the Periodic Table of the Elements, especially of germanium, tin, lead, arsenic, antimony and bismuth.

Examples of these compounds are tin (II) oxide, Tin (IV) oxide, Dki (II) oxide, antimony (III) oxide, bismuth (III) oxide, arsenic (III) oxide, germanium (II) oxide, Lead (II) carbonate, bismuth (III) carbonate, germanium (II) chloride, tin (IV) chloride, lead (II) chloride, Bismuth (III) chloride, antimony (III) chloride, arsenic (III) chloride, germanium (IV) acetate, tin (IV) acetate, arsenic (III) acetate, bismuth (III) acetate, lead (II) nitrate, Tin (II) nitrate and bismuth (III) nitrate.

These compounds can also be used as a mixture of two or more kinds.

The preferred amount of the promoter is in the range of 0.5 to 20 percent by weight based on the amount of catalyst.

The catalyst is applied to a carrier in order to increase the strength of the catalyst and its useful life to increase. Typical examples of the carrier are silica gel, aluminum oxide, activated carbon, silica-aluminum oxide, Zinc oxide, boron oxide and silicic acid boron oxide.

When carrying out the reaction according to the invention, the catalyst is that mentioned on Yes Support material is applied, preferably preheated to the reaction temperature and then the cyclohexanone and the aldehyde, especially formaldehyde or acetaldehyde, through the preheated catalyst directed.

To carry out the reaction in the gas phase, is the reaction temperature of the invention Conversion in a range from 150 to 850 ° C., preferably 250 to 650 C, and the reaction is carried out at atmospheric pressure, reduced pressure or elevated pressure accomplished.

For the production of 2,6-dimethylphenol, which is used as 2,6-xylenol is known according to the invention Process, formaldehyde is reacted with cyclohexanone. If the desired product is 2,6-diethylphenol is, acetaldehyde is reacted with cyclohexanone.

For the reaction of cyclohexanone with the aldehyde to produce 2,6-dialkylphenols theoretically 2 moles of the aldehyde per 1 mole of cyclohexanone required. The / ur implementation of the invention Reaction required molar ratio of

However, aldehyde to cyclohexanone varies with the AM of the aldehyde and depending on the reduction conditions. In general, at least 2 moles of the aldehyde are required for every 1 mole of cyclohexanone. Because of the easier implementation of the implementation and from the economic point of view however, the use of 3 to 10 moles of the aldehyde preferred per 1 mole of cyclohexanone.

In the reaction according to the invention, the reactants can preferably together with certain preheated gases such as nitrogen, carbon monoxide, carbon dioxide, water vapor, argon, helium, be passed into a reaction system to accelerate evaporation.

The process according to the invention makes 6-dialkylphenol in high yield and with high

Preserve selectivity. The compound produced can easily be derived from by-products such as monoalkylphenol, Trialkylphenol or 2,4-dimethylphenol, separated and purified.

From the following Table I it can be seen that inorganic compounds of other metals less effective in terms of yield and less than group Ia of the periodic table of elements Selectivity of the formation of 2,6-dialkylphenols are as the catalyst used in the present invention.

It can also be seen from Table 2 that the use of a promoter other than the promoter according to the invention leads to little or no increase in yield and an increase in the selectivity of the formation of 2,6-dialkylphenols .

table

Kalal) sutor Liquid sales volume o-cresol Yield in Molprozeril. 2,4.6-tri- • 2 Comparison
attempt no. Reaction
Products
(Weight from Cyclo
hexanone
(Mol related to
2,6-Di- Cyclohexanone
2,4-di mcihyl- 1 percent) percent) 7th melhyl- methyl- phenol IO Ca ₃ (PO ₄ ), 8th phenol phcnol 1 - 1 Activated carbon 30th 95 20th 11th 1 2 - 2 Ca ₃ (PO ₄ ), - active- 46 84 24 2 - I. 3 raw (20 Ge 47 100 17th - 2 weight percent) 11th 3 AI ₂ O ₃ 3 4th BeO 59 96 I. 3 4th 5 MgO 45 TI 5 3 8th 6th ZnSO ₄ 35 85 10 5 13th 7th CdO 48 71 8th 2 2 8th CuO 70 40 2 13th 2 9 Ag ₃ PO ₄ 30th 95 13th 2 4th 10 CaO 30th 88 10 - Il 65 50 13th 9

Reaction indications catalyst Promoter
iMolpro / cntl Reaction ailments H hours Cyclohexanone in the disproportion .1: I Liquid c Umsiil / from
Cyclo
hexanone o-Krcsnl Yield in Molpro / enl. • 2.4.h-Tr KaIaI) SiMiIr 15 ml Reaction
Products
! Weight (Molpro / enll bc / ogen on (
2.6-Tue- "yclohcxanon
2.4-Tue- methyl- Kal.ilysalcir 15 ml Originally I ornialdclnd percent) IH mclh> l- melhyl- phenol Starting mixture formaldehyde KjO BjO, 3H ₂ O (2) UiirthfltiUgcsihwindigkcil 15 ml II 98 9 phcnnl phcnol I. Purchfluligspeed 15 ml h KjO V ₂ O, (2) Reaction leniperalur 4511 ( Table 2 79 95 8th 42 8th Reaction temperature 45t) C KjO MoOj (2) KiiiktioiiMl.ülcr 82 99 K) 63 3 Reaction time H hours KjO MnSO ₄ (2) 90 KK) 6th 70 4th 2 Na ₂ O ThO ₂ (2) 80 99 4th 54 8th I. Na ₂ O CrO (2) 81 98 4th 64 2 3 Comparative
attempt no. Na ₂ O NiSO ₄ (2) 85 KX) 13th 40 17th 3 Na ₂ O TiO ₂ (2) 90 99 71 3 "1 41 13th 12th in the mole I 13th 14th Cyclohexanone 15th 16 17th 18th 19th

The invention is illustrated in more detail by the following examples. In these examples, all mean Parts by weight and percentages are mole percent unless otherwise specified.

example 1

200 g of aluminum oxide were introduced into 100 ml of a 5% strength aqueous solution of potassium bicarbonate and the entire mixture was evaporated to dryness and calcined at 650.degree. An aqueous one Solution containing cyclohexanone and formaldehyde in a molar ratio of 1: 4 was poured into a 800 mm long, U-shaped quartz tube with an internal diameter of 20 mm, which contains 15 g of the obtained The catalyst was filled and kept at 600 ° C. in a liquid bath. The flow rate of the starting mixture was 15 ml / h and the duration of the feed was 8 hours. At the same time became nitrogen fed at a flow rate of 180 ml / min. The reaction products were in one recovered with water and dry ice methanol-cooled collecting vessel.

A comparative experiment was carried out using 15 g of aluminum oxide as a catalyst, which had been subjected to a thermal treatment at 650 ° C. The results are in Table 3 listed.

When only alumina was used as the catalyst, the amount obtained was liquid Reaction products are significantly lower because of the decomposition of the reaction participants. A bigger one Amounts of carbon monoxide, carbon dioxide, meihan, alhan, and ethylene were in the gaseous products noted after the reaction. In addition, there was a remarkable formation of phenol by dehydrating cyclohexanone, m-cresol and p-cresol in addition to o-cresol, 2,4-dimethylphenol and 2,4,6-trimethylphenol, and consequently very poor selectivity. In contrast in addition, the selectivity of the formation of 2,6-dimethylphenol was markedly improved and 2,6-dimethylphenol produced in high yield when a potassium oxide catalyst supported on aluminum oxide has been used.

Table 3

Cyclohexanone

Cyclohexanol

ίο phenol

o-cresol

m- and p-cresol

2,6-dimethylphenol

2,4-dimethylphenol

Other dimethylphenols

2,4,6-trimethylphenol ...

Others ..... "

Amount of liquid reaction products
(Weight percent)

I comparison I

5.5

1.7

35.9

18.9

12.3

5.7

7.3

!,8th

3.0

8th?

58.5

K ₃ O ΛΙ, Ι),

iVeri.ihrm

the

0.4 0

3.8 13.4

0 74, p

1.8

3.2

2.4

88.9

Example 2

The effect of in the starting formaldehyde in the solution of the reactants containing methanol was made using silica-alumina and sodium carbonate applied to silica-alumina as a catalyst

jo examined. 500 g of silica-aluminum oxide were introduced into 200 ml of a 5% strength aqueous solution of sodium carbonate and the mixture was evaporated to dryness and calcined at 550 ° C. for 4 hours. An aqueous solution containing cyclohexanone. Shape-

aldchyd and methanol in a molar ratio of 1: 4: 0.1 was introduced into the same reaction tube as in Example 1, the one with 1 5g of the one prepared there The catalyst was charged and kept at 350.degree. The respondents were with initiated at a flow rate of 15 ml / h for 8 hours. The attempt was made in the absence of Methanol repeated. A comparison was made using 15 g of alumina as Catalyst carried out in the absence of

4S methanol subjected to a heat treatment at 650 ° C had been. The results are shown in Table 4.

Table 4 Hot reaction products |%]

Cyclohexanol

phenol

o-cresol

m- and p-K resol

2,6-dimethylphenol

2,4-dimethylphenol

Other dimethyl alcohols

2,4,6-trimethyl benzene

Others

Amount of reaction products (weight percentage)

¹ I without MeIhHiIi) I ^! | With methanol

Silicic acid

Aluminum oxide

(Comparison)

10.3

14.6

23.1

12.8

8.1

11.0

0.3

3.0

I ft. I

70.1

Kalalysalor

Na ₂ Cf)., On

Kicsclsiiurc- Aluminum mmd ')

Well, CO, up

Kicsc Acid Aluminiiim.md ^; |

! Procedure of the binding)

0.4

1.4
14.2

0.1
80.9

0.6

2.0

0.8

94.3

0.5

1.4 14.3

0 80.3

0.4

2.0

Example 3

5 (X) g of activated charcoal was added to an aqueous solution containing methanol containing 0.1 mol of sodium phenolate contained. The entire mixture was evaporated to dryness and then at 400 ° C in one Further dried in a nitrogen atmosphere to activate the catalyst. 15 g of this catalyst were introduced into the reaction tube used in Example I and the reaction took 8 hours 25O ° C carried out. There were 84 g of liquid reaction products won. The organic layer of the reaction products was separated and filtered through Gas chromatography analyzed. It consisted of 70.3% 2,6-dimethylphenol. 11.3% o-cresol and 1.3% 2,4,6-trimethylphenol.

Example 4

2 g of lithium hydroxide were added to 300 g of silica aluminum oxide / zinc oxide applied in a weight ratio of 1: 3 and the product obtained Calcined at 400 ° C. for 2 hours. 15 g of this catalyst were placed in the same reaction tube as in the Example 1 is poured in and then the reaction is carried out for 6 hours at 40 ° C. in that described in example 1 Way done. 64 g of liquid reaction products were obtained. By gas chromatographic Analysis found that the separated organic from the liquid reaction products Layer contained 65.2% 2,6-dimethylphenol, 18.5% o-cresol and 3.3% 2,4,6-trimethylphenol.

Example 5

800 g of silica gel were dissolved in 500 ml of a 5% strength aqueous solution of cesium carbonate and sodium carbonate given in a weight ratio of 1: 5 and the total mixture evaporated to dryness and calcined at 450 ° C for 2 hours. This gave a carrier applied to silica gel Cesium Sodium Catalyst. 15 g of this catalyst were used in that described in Example 1 Filled into the reaction tube and the reaction in the same manner as in Example 1 at 450 ° C. during the following specified duration. The results obtained are shown in Table 5.

Table 5
Composition of the reaction products

Amount of Ift-Di- o-K resol 14.6-tri- Reak liquid nicllnl- melhyl functional Reaction phcnnl phenol length of time Products {"η I {"«) iSitl ) ((ii'not- 10.2 pro7cnt) 83.0 11.1 3.2 1 90.2 84.2 11.7 1.8 12th 91.3 80.0 13.2 1.6 96 92.5 75.6 1.5 44 93.0

Example 6

200 g of silica gel were introduced into 100 ml of a 5% strength aqueous solution of sodium carbonate and the entire mixture was evaporated to dryness and then calcined at 600 ° C. for 4 hours. 15 g of this catalyst were charged into the same reaction tube as in Example 1 and an aqueous mixed solution containing 3 parts of acetaldehyde, and part Cyclohexanone I contained is introduced in the manner described in Example 1 for 8 hours at 500 ^r C in the reaction tube. 91 g of liquid reaction products were collected and the organic layer was separated therefrom. It was found by gas chromatographic analysis that this organic layer contained 68.5% 2,6-diethylphenol, 13.8% o-ethylphenol and 5.3% triethylphenol.

Example 7

200 g of silica gel and lead (II) oxide in a weight ratio of 10: 1 were in 150 ml of a 5% registered aqueous solution of potassium carbonate and evaporated the entire mixture to dryness and then calcined at 450 ° C. for 2 hours. 15 g of this catalyst was charged into the same reaction vessel as in Example 1 and then during

jo 4 hours, an aqueous, dissolved mixture of 4 parts of acetaldehyde and 1 part of cyclohexanone introduced at a temperature of 450 ⁰ C in the reaction tube. Liquid reaction products were obtained in an amount of 88.8% and the organic layer was separated therefrom. The analysis of the organic layer ery, from an average content of 72.3% 2,6-diethylphenol, 14.6% o-ethylphenol and 4.3% triethylphenol.

Example 8

An aqueous sodium carbonate solution containing 0.05 mol of sodium carbonate and then an aqueous solution of arsenic acid containing 0.01 mol of arsenic acid were added to 200 g of silica sol. Thereafter, 20 g of aluminum hydroxide sol were added to the mixture obtained and the entire gel obtained was evaporated to dryness under reduced pressure, ^{calcined at 500 °} C. for 5 hours and pulverized. 15 ml of this catalyst were introduced into a 800 mm long quartz tube having 20 mm inner diameter, which was preheated for 2 hours at 38O ⁰ C. 200 ml of an aqueous solution containing 9.5 g of formaldehyde and 10.5 g of cyclohexanone were then passed in continuously over a period of 8 hours at a flow rate of 20 ml / h. 150.3 g of liquid reaction products were obtained. Gas chromatography of the organic layer separated from the liquid products revealed that this organic layer contained 86.2% 2,6-dimethylphenol, 10.3% o-cresol and 2.0% 2,4,6-trimethylphenol.

Example 9

A catalyst was prepared in the same way as in Example 8, with the modification that 0.02 mol of finely powdered germanium oxide was used instead of arsenic acid. The reaction was carried out using 15 ml of the catalyst obtained at 35O ⁰ C for 3 hours in the same f> o manner as conducted in Example 8. FIG. 58.5 g of liquid reaction products were obtained. The organic layer from these reaction products contained 83.2% 2,6-dimethylphenol. 12.3% o-cresol and 1.6% 2,4,6-trimethylphenol.

Example 10

An aqueous solution was added to KK) g of silica gel given; which contained 0.05 mol of lead (II) nitrate, and

109 M.s;> y

17?

ίο

an aqueous solution containing 0.025 moles of potassium hydroxide. The mixture obtained was evaporated to dryness under reduced pressure and then ^{calcined at 600 °} C. for 5 hours in order to activate the catalyst. 15 ml of this catalyst were introduced into a U-shaped quartz tube with an inner diameter of 20 mm and a length of 800 mm, and the same solution of reactants as in Example 8 was introduced into the reaction tube at an inflow rate of 15 ml / h for 10 hours at 550.degree. 126.8 g of liquid reaction products were obtained. The organic layer separated therefrom contained 87.3% 2,6-dimethylphenol, 9.1% o-cresol and 0.8% 2,4,6-trimethylphenol.

Example 11

To 600 g silica sol, an aqueous solution of 0.1 mole was added potassium antimonyl tartrate and dilute hydrochloric acid and evaporated to the total mixture at a temperature between 70 and 80 ⁰ C under reduced pressure to dryness, calcined for 6 hours at 500 ° C, pulverized in a 1 n-Potassium carbonate solution entered at a temperature of 50 to 60 ° C, filtered off and again calcined at 500 ° C for 6 hours. 15 ml of the catalyst obtained were introduced into the reaction tube described in Example 8 and 200 ml of an aqueous LOSUi ₁ J containing 23 g of formaldehyde and 10 g of cyclohexanone were poured continuously in the manner described in Example 8 at a flow rate of 10 ml / h 6 Hours initiated. 58.4 g of liquid reaction products were obtained and the organic layer was separated therefrom. The composition of the organic layer as analyzed by gas chromatography was 88.3% 2,6-dimethylphenol, 8.2% o-cresol and 1.4% 2,4,6-trimethylphenol.

Example 12

100 g of silica gel was introduced into an aqueous solution of 0.03 mol of potassium stearate and that The mixture was left to stand overnight, evaporated to dryness, calcined at 550C and in KX) ml registered a 3% aqueous solution of sodium carbonate. It was then evaporated to dryness again and calcined again at 550 ° C. An aqueous solution containing cyclohexanone and acetaldehyde in the molar ratio of 1: 3, was in the reaction tube used in Example 8, which with 15 ml of the catalyst obtained was charged with a

ίο flow rate of 15 ml / h for 10 hours 550 C initiated. The organic layer separated from the liquid reaction products contains 74.8% 2,6-diethylphenol, 13.3% o -ethylphenol and 2.1% triethylphenol.

Example 13

1 part of sodium oxide, 0.2 part of lead (II) oxide and ίο 3 parts of arsenic (III) oxide were added to 100 parts of activated carbon 15 ml of this catalyst were applied Filled into the same reaction tube as in Example 8 and the reaction in the same manner as in Example 8 was stirred at 430.degree. There were 148 g liquid reaction products obtained whose organic layer «8.5% 2,6-dimethylphenol and 8.1% Contained o-cresol.

Example 14 to 19

An aqueous solution of cyclohexanone and formaldehyde in a molar ratio of 1: 3, the catalysts as prepared in Example I was eingcführt in the same reaction tube as in Example 1, with 15 g were charged and kept at 450 ⁰ C. The reaction was carried out in the same manner as in Example 1 at a reactant inflow rate of 15 ml for 8 hours. The results obtained are shown in Table 6.

Table 6

example

catalyst

Cs ₂ O

CH ₃ COOK

After ₃

RbNO ₃

NaHCO ₃

CH ₃ C = CHCOCH ₃

ONa

Liquid Reaction products (Weight percent)

87
90
92
85
88
88

Sales in

Cyc'o-

hexanone

(Mole percent)

99
99
100
100
100
999

o-Krescl

Il

11th

Bulge in mole percent.
based on cyclohexanone

2.6-Tue- 2.4-Tue- methyl- melhyl- phenol phenol 73 1 75 2 77 2 69 1 75 1 81

2.4.6-trimethylphenol

Examples 20 to 25

200 ml of an aqueous solution are introduced into the 9.5 g formation tube. The reaction tube was mi

Aldehyde and 10.5 g of cyclohexanone contained, 15 ml of were obtained in the same way as in the examples

continuously filled under the same conditions as presented catalysts and was at 450 "(

in example 8 in the react described in example 8 held. The results are shown in Table 7

at
game Kal; ilys, i1or 20th KjO 21 KjO 22nd KjO 23 Na ₂ O 24 • Na ₂ O 25th Na ₂ O

11th

Promoter

GeCI ₂
PbCI ₂

As

OCCH.,

SbCI ₃
SnO ₂

Table 7

Amount of animal liquid

Reaction products

Kiewiehlspro / enl)

94
94
97
93

98
97

Conversion of cyclohexanone (MoI-pro7cnt |

KK)

K) O

KX)

KK) 100

Howling in Molprii / cnl.
based on cyclohexanone

resol 2,6-Tue
methyl-
phenol 2,4-di
melhyl-
phenol 2.4,6-tri
methyl-
phenol 0 79 2 4th 83 2 3 88 I. 2 3 85 .._ I. 3 89 3 6th 83 2

Claims (1)

Claim: Process for the preparation of 2,6-dialkylphenols by reacting cyclohexanone with aldehydes at elevated temperature in the gas phase in the presence of a catalyst, thereby characterized in that the reaction at a temperature of 150 to 85O ° C, preferably 250 to 650 "C, in Gegenwarl a compound of a metal of the first main group of the periodic table applied to a carrier of the elements as a catalyst, which preferably also carries out a compound; Metal of the 4th or 5th main group of the period systems of the elements as a promoter.