CA1131246A - Process for the production of unsaturated esters - Google Patents

Abstract

(Jap. 142,244/78) ABSTRACT OF THE DISCLOSURE

The invention relates to a process for the production of an unsaturated glycol diester by the reaction of a conjugated diene compound, a carboxylic acid and molecular oxygen in the presence of a solid catalyst.
For example, 1,4-diacetoxy-2-butene is prepared at high conversion and high selectivity by reacting butadiene, molecular oxygen and acetic acid in the presence of a solid catalyst containing palladium, tellurium and at least one element selected from the group consisting of tin, germanium and zinc.
The production is an intermediate for the preparation of 1,4-butanediol.

Description

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1 BACKGROUND OF THE INVENTIO~

2 1. Field of ~he Invention

3 This invention relates to a process for the pro-

4 duction of an unsaturated glycol diester ~rom a conjugated diene compound and, more particularly, it is concerned ~Jith 6 a process for the production of an unsaturated glycol diester 7 comprising reacting a conjugated diene compound, carboxylic 8 acid and molecular oxygen in the presence of a solid 9 ca~alyst.
2. Description of the Prior Art 11 The above reaction is k~own. In particular, 12 when the carboxylic acid is acetic acid, the reactior. may 13 be depicted illustratively as follows:
14 Rl R6 \ C~C ~-C \ + 2CH3COOH + 1/2 2 17 ll l3 l4 ~5 18 R2~ C===C--C n6 + H~O

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21 wherein Rl to R6 are individually a hydrogen a~om or a 22 hydrocarbon group9 preferably an alkyl group having 1 to 23 carbon atoms.
24 Unsaturated glycol diesters are very useful as raw materials for various chemical processes. Above all, '~
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l 1,4-glycol diesters are particularly important as raw 2 materials for preparing organic solvents such as tetrahydro-3 furan or synthetic resins such as polyurethane resins and 4 polybutylene terephthalate and various proposals have hitherto ~een made for the production of the same.
6 In ~he process for the production of 1~4-glycol 7 diesters, it has been considered desirable to use a palladium 8 type catalyst. For example, in U.S. Patent 3,755,423, 9 1,4-diacetoxy-2-butene is obtained with high conversion as well as high selectivity by reacting 1,3-butadiene with ,ll acetic acid using a solid catalyst containing palladium, at 12 least one of antimony and bismuth and at least one of 13 tellurium and selenium.
14 Even in the case of using this catalyst, however, the catalyst efficiency, in particular, the palladium 16 efficiency (Mols of diacetoxybutene formed/Catalyst palladîum 17 atnm,hour) is quite low and unsatisfactory in comparison 18 with t'ne catalyst for the synthesis of vinyl acetate by 19 ethylene process which has already bPen practiced on a commercial scale as a reaction of this type 21 A representative patent of Mitsubishi ~hemical 22 Company, Japanese Patent Public Disclosure No. 11812/74, 23 reported that the addition of a small amount of tellurium 24 to the Pd/C catalyst results in a dramatic increase in activity for ace~oxylation with high selectivity to 1,4-26 diacetoxy-2-butene (92%).
27 On thP other hand, BASF's patent, Japanese 28 Pa~ent Public Disclosure No. 63119/76, repor~ed that carbon-29 suppor~ed~palladium telluride (Pd4Te/C) catalyst, which is prepared with a controlled ratio of Pd to Te and gave no 31 diffraction line of metallic palladium in X-ray analysis, 32 shows good activity for acetoxylation.
33 Both palla~ium efficiency for diacetoxy~utenes 34 (DAB) formation over Pd-Te/C (8.4 mol-DAB/g-atom Pd/Hr~ and Pd4Te/C catalyst (6.4), however, remained at an insufficient 36 level as a commercial catalyst.

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1 . Other patents in this area include U.S. Patents 2 3,671,577; 3,922,300; 4,075,413; 4~121,.039 and the 3 followin~ Japanese Patent Public Disclosures:
4 No. 47-39003 14 Thus the prior art has taught that in the preparation of solvents such as 1,4-butanediol from 16 butadiene, the key to the process is the initial acetoxyla-17 tion step wherein a carbon supported Pd-Te catalyst system 18 is used~ -19 SUMMARY OF 1~ INVENTION
Applicants have made studies on a catalyst 21 system capable of producing unsaturated esters, for example, 22 1,4-diacetoxy-2-butene9 with a higher catalytic efficiency 23 suitable for co~mercial scale operation for the purpose of 24 solving the above described problems and ha~e found that unsaturated esters can be obtained with a high catalytic 26 efficiency and a higher selectivity by ~he use of a solid 27 catalyst cont~ining (a) palladium, (b~ tellurium and (c) 28 at least one of ~in~ germanium and lead. The present in-29 vention is based on this finding.
That is to szy9 the present invention provides 31 a process for the production of an unsaturated glycol 32 diester, which comprises reactin~ a conjugated diene compoun~
33 a carboxy~ic acid and molecular oxygen in the presence of 34 a solid catalyst containing (a) palladium, ~) tellurium 35 and (c) at least one of Group IV elements of the Periodic 36 Table selected from the group consisting of tin, germanium 37 and lead. These are the heavy metals of Group IVA.
38 3E~AI~J7 D~sc~ lo~
39 The metallic components used for the preparation ~3~Z~

1 o the catalyst used in the process of the present invention 2 come from the following compounds:
3 For palladium, there may be used palladium 4 chloride, palladium nitrate, palladium sulfate, palladium hydroxide, palladium oxide and the like.
6 For tellurium, there may be used tellurium 7 dio~ide, tellurium trioxide, telluri~m dichloride, 8 tellurium tetrachloride, tellurium tetraoxide, telluric g acid and the like.
For the third components, i.e., tin, germanium ll and lead, there may be used their oxides, chlorides, 12 nitrates, carboxylates and the like, for example, stannous 13 chloride, tin nitrates, tin oxides, germanium tetrachloride, 14 germanium oxides, germanium hydroxides, lead nitrate, lead chloride, lead acetate, etc.
16 The support for the catalytic components is 17 not particularly limited, but, for example, active carbon, 18 silica gel, silica-alumina, alumina~ pumice, kieselguhr l9 and silicon carbide may be used. In particular, active carbon is preferred. The support may be used as it is 21 commercially sold or after it is subjected to a heat treat-22 ment or an acid treatment with nitric acid or hydrochloric 23 acid.
24 The method of suppor~ing the catalytic components may suitably be chosen from the ordinary methods of pre-26 paring supported catalysts. In the case of supporting by 27 impregnation, for example, catalytic components are dis-28 solved in a suitable solvent such as water7 aqueous acidic 29 solution of hydrochloric acid or nitric acid, aqueous alkaline solution or organic solvent, in which a support 31 is immersed. Catalytic components may simuLtaneously or 32 successively be dissolved in a solvent followed by 33 impregnation.
34 In the present invention, the amounts of the catalytic components supported are preferably adjusted as 36 follows. The amount of palladium supported is preferably ~L 3~

l 0.1 to 10.0 % by weight and even if less than 0.1 % by 2 weight or more than 10.0 % by weight, the reaction can 3 proceed. The amount of tellurium is preferably 0.01 to 4 5.0 % by weight, more preferably 0.1 to 3.0 % by weight.
S The amount of at least one of tin, germanium and lead is 6 preferably 0.01 to 10.0 % by weight, more preferably 0.1 7 to 3.0 % by weight of the total catalyst.
8 The atomic ratio of tellurium and at least 9 ona of tin, germ~nium and lead to palladium in the catalyst is preferably 0.05 to 10 gram atoms to 1 gram atom of 11 palladium, more preferably 0.1 to 5 gram atoms of teLlurium 12 and 0.1 to 2 gram atoms of at least one of tin, germanium 13 and lead to 1 gram atom of palladium.
14 The support having the catalytic components is then subjected to removal of the solvent and to reduction 16 in a hydrogen stream or in a gaseous stream containing an 17 organic compound capable of reducing, in general, at a re-18 ducing temperature of 150 to 500C., preferably 200 ~o l9 400C., for 2 to 10 hours, thus producing a catalyst.
2~ Examples of the conju~ated diene compound usPd 21 as a raw material in the process of the present invention 22 are 1,3-bu~adiene and hydrocarbon substituted derivatives 23 thereof such as isoprene, 1,3-pentadiene, 2,3-dimethyl-24 1,3-butadiene, 1,3-hexadiene, ~,4-hexadiene~ 1,3-oc~adiene and 4-phenyl-~butadiene, and cyclic conjugated diene 26 compounds such as cyclopentadiene, 1,3-cyclohexadiene and 27 1,3~cyclooctadiene. Above all~ 1,3-butadiene is preferred.
28 It is not always required that the con~ugated diene compound 29 be pure, but nitrogen, carbon dioxide or a lower saturated hydrocarbon such as methane, ethane, propane or butane 31 may be admixed therewith.
32 The carbo~ylic acid as another raw material 33 in the process of the present invention may be selected from 34 saturated or unsaturated aliphatic carboxylic acids and aromatic carbaxylic acids having 2 to 20 carbon atoms.
Lower aliphatic mono carboxylic acids containing 2 to 4 ~3~2a~;

1 carbon atoms such as acetic acid, propionic acid and 2 butyric acid are preferably used and, in particular, acetic 3 acid is more preferable.
4 The molecular oxygen used in the process of the present invention does not have to be pure but may be diluted 6 wi~h an inert gas such as nitrogen or carbon dioxide, and 7 of course may be air.
8 The reaction conditions employed in the process 9 of the present invention are as follows: The reaction 10 may be carried out batch-wise or continuously in liquid 11 phase using a fixed bed or fluidized bed. The reaction 12 temperature, pressure and feed quantities of a conjugated 13 diene compound, carboxylic acid and molecular oxygen are 14 not particularly limited but preferably the reaction 15 temperature ranges from 40C to L80C.~ the pressure 16 ranges from atmospheric to 100 Kg/cm2 and the molar ratio 17 of conjugated diene compound/carboxylic acid/molecuLar 18 oxygen is in the range of 1/0.5-10.0/0.1-5Ø
19 The following examples are provided in order to illustrate the present invention in detail without limit-21 ing the same.
22 Example_ 1 23 0.1750 g of palladium chloride and 0.0250 g of 24 tellurium dioxide were dissolved in 40 ml of 6N hydrochloric 25 acid, to which a methanol solution of 0.2214 g of stannous 26 chloride (SnC12 2H20~ was added, and 10 g of active carbon 27 of 24 to 42 mesh, previously heated and refluxed with 15 28 % by weight nitric acid for 6 hours, was immersed in the 29 resulting solution at room tempera~ure for 24 hours. After 30 the immersion, the mixture was then evaporated gradually 31 to dryness on a warm water bath, dried at 150C for 3 32 hours in a nitrogen stream ln a tube and reduced with 33 nitrogen saturated with methanol at room temperature at 34 200C ror 3 hours and at 400C for 2 hours, thus obtaining 35 a catalyst containing 1.05 % by weight of palladium, 36 0.20 % by weight of tellurium and 1.16 % by weight of tin ,, ~ - 6 -~3~3~

1 and having a palladium/~ellurium/tin atomic ratio of 2 1.0/0.16/l.o 3 4 g of the catalyst prepared in this way was 4 charged to a reaction tube of stainless steel with an inner diameter of 18 mm, through which glacial acetic 6 acid, butadiene and oxygen were passed at a rate of 12.5 7 ml/hr, 60 mmol/hr and 40 mmol/hr respectiveLy, and 8 the reaction was carried out continuously at a reaction 9 temperature of 80C.
Analysis of the product after passage of 5 hours 11 from the start of the reaction gave the space time yield 12 (glcatalyst 1 hr), palladium efficiency (mollpalladium atom-hr) 13 and 1,4-isomer selectivity (%) shown in Table 1.
14 ExamPles 2 and 3 The preparation of a catalyst and the reaction 16 using the same were carried out in a manner analogous to 17 Example 1 except that 0.2124 g of germanium tetrachloride 18 or 0.3271 g of lead nitrate was added in place of the 19 stannous chloride of Example 1, thus obtaining the results shown in Table 1. In Example 2 7 a solu~ion of germanium 21 tetrachloride in absolute alcohol was added and in Example 22 3, a svlution of lead nitrate in hydrochloric acid was added.
23 ~om~arative Exam~les 1 and 2 24 The preparation of a catalyst and the reaction using the same were carried out in a manner analogous to 26 Example l except that a combination of palladium chloride 27 with tellurium dioxide or palladium chloride with stannous 28 chlori~e was used to obtain the results shown in:Table 1.
29 Comparative Example 3 The preparation of a catalyst and ~he react;on - 31 using the same were carried out in a manner analogous to 32 Example 1 except that a combination Oc 0.0250 g of tellurium 33 dioxide and 0.2214 g of stannous chloride only was used 34 to obtain the results shown in Table 1 ' .

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9 Each of cuprous chloride, nickel nitrate, ferric nitrate, ammonium molybdenate, potassium acetate, antimony 11 trichloride and bismuth nitrate was dissolved in 6N hydro-12 chloriG acid with palladium chloride and tellurium dioxide.

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1 Example 4 2 The catalyst of palladium-tellurium-tin/active 3 carbon prepared in Example l was charged to a pressure-4 resisting reaction tube of stainless steel with an inner S diameter of 14mm, through which 6~7 ml/hr of glacial 6 acetic acid, 4.0 ml/hr of liquid 1,3-butadiene and 470 N
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12 Comparative Example 11 13 The reaction was carried out in a manner analogous 14 to Example 4 except that the catalyst of palladium-tellurium/
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l Exam~les 9-10 and Com~arative Examples 12-14 2 Comparison with BASF and Mitsubishi Chemical Co.
3 processes in catalyst performance is summarized in Table 5.
4 The catalysts of Examples 9 and 10 were prepared in a manner analogous to Example 1.
6 Both Examples 9 and 10 gave a Pd efficiency superior 7 to Comparative Examples 12-14. The Pd-Te-Sn/C catalyst in 8 Example 10 gave excellent palladium efficiency (32.7 mol-9 DAB/g-atom Pd/hr) which is substantially equivalent to the commercial one of vinyl acetate synthesis from ethylene over 11 a Pd catalyst. Pd efficiency for commercial vinyl acetate 12 synthesis is estimated to be about 50. This value corres-13 ponds to about 25 Pd efficiency for diacetoxylation.

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Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a process for the production of an un-saturated ester which comprises reacting a conjugated diene compound, a carboxylic acid and molecular oxygen in the presence of a solid catalyst containing (a) palladium and (b) tellurium, the improvement which comprises includ-ing in the catalyst (c) at least one of Group IV elements of the Periodic Table selected from the group consisting of tin, germanium and lead.

2. A process according to claim 1 in which the conjugated diene compound is butadiene which may be sub-stituted by alkyl or phenyl groups and the carboxylic acid may be aliphatic, alicyclic or aromatic.

3. A process according to claim 2 in which the butadiene is substituted by at least one methyl group.

4. A process according to claim 2 or 3 in which the carboxylic acid is a lower aliphatic monocarboxylic acid containing 2-4 carbon atoms.

5. A process according to claim 1 in which the reactants are butadiene, acetic acid and molecular oxygen and 1,4-diacetoxy-2-butene is obtained

6. A process according to claim 1 or claim 5 in which the reaction temperature is in the range of-40°
to 180°C, the reaction pressure is in the range of atmos-pheric to 100 Kg/cm2 and-the molar ratio of conjugated diene compound/carboxylic acid/molecular oxygen is in the range of 1/05.-10.0/0.1-5Ø

7. A process according to claim 1 or claim 5 in which the atomic ratio of tellurium and at least one of the metals tin, germanium and lead, to palladium, in the catalyst is 0.05 to 10 gram atoms to 1 gram atom of palladium.

8. A process according to claim 1 or claim 5 in which the atomic ratio of tellurium to at least one of the metals tin, germanium and lead, to palladium is 0.1-5/
0.1-2/1.