DE2758124C3 - Process for the preparation of aliphatic hydroxycarbonyl compounds etherified with aliphatic groups - Google Patents

Description

a) 3 or more layers of silver crystals, some of the layers of silver crystals being 30 to 85 Percentage by weight of the catalyst with particles of grain size 1 to 2.5 mm, part of the layers Silver crystals 2 to 30 percent by weight of the catalyst with particles of grain size 0.75 to 1 mm and the remaining part of the layers of silver crystals 8 to 50 percent by weight of the Contain catalyst with particles of grain size 0.2 to 0.75 mm, and one or more layers

Copper crystals which contain 1 to 40 percent by weight of the catalyst with particles having a grain size of 0.2 to 0.75 mm, or
b) 3 or more layers of silver crystals, some of the layers of silver crystals 30 to 85 percent by weight of the catalyst with particles of grain size 1 to 2.5 mm, some of the layers of silver crystals 2 to 30 percent by weight of the catalyst with particles of grain size 0.75 to 1 mm and the remaining part of the layers of silver crystals contain 8 to 50 percent by weight of the catalyst with particles of grain size 0.2 to 0.75 mm, and one or more layers of copper crystals that contain 0.5 to 40 percent by weight of the catalyst with particles of grain size 0 , 2 to 0.75 mm, and one or more layers of catalyst particles with 70 to 99 percent by weight copper, 0.9 to 20 percent by weight tin and 0.1 to 10 percent by weight phosphorus, based on the weight of these particles, of these elements, wherein these layers contain catalyst particles from 0.5 to 10 percent by weight of the catalyst with particles having a grain size of 0.2 to 0.75 mm,

oxidized at a temperature of 450 to 700 ° C.

The reaction in the case of using methyl glycol can be represented by the following formulas be reproduced:

Groups of etherified hydroxy alcohols are starting materials of the formula

2 CH ₃ O-CH ₂ -CH ₂ OH + O ₂

> 2CH ₃ O-CH ₂ -CHO + 2H ₂ O.

30th

R ¹

R ¹ - C

R ¹ IO

R ¹

-CR ²

(D

40

In comparison to the prior art, the process according to the invention surprisingly provides a better overall result in a simpler and more economical way with regard to yield, space-time yield and purity of the end product and service life of the catalyst. The life of the catalyst is usually at least 30 days in the case of methoxyacetaldehyde. All these advantageous results are surprising in view of the state of the art, in particular the teaching of Houben-Weyl, because in view of the high temperatures according to the invention one should have expected at least a substantial deterioration in the yield and considerable formation of decomposition products. With regard to the in Zh. Prikl. Khim. The processes described do not need to be added to water or inert gas. The laborious procedure under vacuum and with special catalyst treatment is avoided. High specific catalyst loadings, e.g. B. from 0.4 to 2.5 t / m ² of catalyst bed cross-sectional · hour compared to 0.15 t / m ² of catalyst bed cross-section ■ hour (... Prikl Khim Zh) can be obtained. Compared to the process described in US Pat. No. 2,170,855, the yield and conversion are higher.

Appropriate aliphatic hydroxycarbonyl compounds etherified with aliphatic groups are such final substances of the formula

50

55

60

65 R ¹

R ¹ - C-

R ¹

R ¹

-C-

R ¹

OH

-C - R ²
H

in which the individual radicals R ^{1 can be} identical or different and each represent a hydrogen atom, an aliphatic radical or the radical R ³ -O-, where at least one radical R ¹ denotes the radical R3-O-, R ² denotes a Hydrogen atom or the rest

R ⁴

R ⁴ - C-

R ⁴

R ⁴
-C-

stands, χ and ζ can be identical or different and each represent 0 or an integer, R ³ denotes an aliphatic radical, the individual radicals R ^{4 can be} identical or different and each represents a hydrogen atom, an aliphatic radical or the radical R ³ - O- mean in which R ^{3 has} the aforementioned meaning. Preferred starting materials II and correspondingly preferred end products I are those in whose formulas the individual radicals R ^{1 can be the} same or different and each represent a hydrogen atom or an alkyl radical having 1 to 5 carbon atoms or the radical R ³ -O-, with at least one radical R ¹ denotes the radical R ³ -O-, R ² denotes a hydrogen atom or the radical

R ⁴

R ⁴ —C-

R ⁴

R ⁴
-C-

R ⁴

and, accordingly, as aliphatic with aliphatic, R ³ denotes an alkyl radical having 1 to 5 carbon atoms, R ⁴ denotes a hydrogen atom or an alkyl radical having 1 to 5 carbon atoms or the radical R ³ —O -, in which R ^{3 has} the aforementioned preferred meaning , is, χ and ζ can be identical or different and each represent 0 or an integer, in particular 0.1 or 2. The abovementioned radicals can also be replaced by groups which are inert under the reaction conditions, e.g. B. alkyl groups having 1 to 4 carbon atoms, may be substituted.

There come z. B. as starting materials II in question: methyl, ethyl, n-propyl, isopropyl, η-butyl, sec-butyl, isobutyl, tert-butyl-ethylene glycol; Corresponding propylene (1,2) -, propylene (1,3) -, butylene (1,2) -, butylene (1,3) -, butylene (2,3) -, butylene (1 , 4) -, isobutylene, pentylene (l, 5) -, hexylene (l, 6) glycol ethers; ethanol, n-propanol, 2-hydroxypropane, n-butanol, 2-hydroxybutane, isobutanol and corresponding di- or triethyl (a) ethers; in κ-, «'-, β, β'-, λα'-,

β, β'-, <χ, β'-, J3, a'-position to the hydroxyl group accordingly several times or advantageously once, twice or three times by the methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert.- Butoxy, sec-butoxy, isobutoxy group-substituted 2-hydroxypropane, 2-hydroxybutaru, 2-hydroxypentane, 3-hydroxypentane.

Both pure oxygen and gases containing free oxygen, in particular air, can be used as the oxidizing agent. Oxygen, generally in the form of air, and starting material II are expediently used in a molar ratio of from 0.25 to 0.8, in particular from 0.35 to 0.6 mol of oxygen per mole of starting material II. The use of inert gas is not necessary, but on the other hand does not interfere with the conversion either. If necessary, hot inert gases, advantageously nitrogen or low-soot combustion gases that contain no catalyst poisons, eg. B. from a temperature of 600 to 800 ⁰ C, heat the catalyst.

The total layer thickness of the catalyst is 5 to 100, preferably 10 to 30 mm. The catalyst particles in the form of silver crystals are in the catalyst of the usually vertically positioned Depending on the grain size, the reactor is arranged in an upper, middle or lower part of the overall layer. That Starting mixture of steam of the starting material II and oxygen or air is generally from above led downwards so that the upper layer (upper layers) is at the same time as the starting mixture facing part means. In the case of reactors of a different design or a different management of the starting mixture All information in the description about the upper (lower) part of the catalytic converter apply accordingly to the corresponding part facing the starting mixture (the reaction mixture discharged). z. B. at horizontally arranged reactors for the front (rear) part of the catalyst. The following information with respect to the proportion in percent by weight of all catalyst particles relate to the total weight of the Catalyst, d. H. both the silver crystals and copper crystals as well as the copper / tin / phosphorus catalyst particles (Cu / Sn / P particles). In the lower part of the silver crystals there are 30 to 85, preferably 50 to 78 percent by weight of all catalyst particles, in the middle part of the silver crystals 2 to 30, preferably 5 to 25 percent by weight of all catalyst particles, in the upper part of the silver crystals 8 to 50, preferably 13 up to 35 weight percent of all catalyst particles. The particles of the lower layer part have grain sizes from 1 to 2.5, that of the middle layer part from 0.75 to 1, that of the upper layer part 0.2 to 0.75 mm. Everyone Silver layer part can consist of one or more layers, preferably of 1, 2 or 3 layers. A 4 to 7 silver layer catalyst is preferred, especially a 4 or S silver layer catalyst. Each of these layers differs from the other in the grain size of the silver crystals and mostly also in the associated weight fraction of the total catalyst.

If the upper silver layer part has 2 silver layers, see below its lower silver layer preferably has a proportion of 4 to 46 percent by weight and particles of one Grain size from 0.4 to 0.75 mm and its upper silver layer corresponding to a weight fraction of 4 up to 46 percent by weight and particles with a grain size of 0.2 to 0.4 mm. Are 3 layers of silver in the top If part of the silver layer is present, with reference to the percentage by weight of the total catalyst (grain size of the Particles) preferred: upper silver layer 3 to 45 (0.2 to 0.4 mm); middle silver layer 3 to 45 (0.4 to 0.6 mm); lower silver layer 2 to 44 (0.6 to 0.75 mm) weight percent. The middle one is accordingly Silver layer part with reference to weight fraction (grain size of the particles) preferred:

a) 2 layers of silver:
upper silver layer

1 to 29 (0.75 to 0.9 mm) weight percent;
lower silver layer

1 to 29 (0.9 to 1 mm) wt%.

b) 3 layers of silver:
upper silver layer

0.7 to 28.7 (0.75 to 0.8 mm) weight percent;
middle silver layer

0.7 to 28.7 (0.8 to 0.9 mm) weight percent;
lower silver layer

0.6 to 28.6 (0.9 to 1 mm) weight percent.

For the lower part of the silver layer, the following are preferred:

c) 2 layers of silver:
upper silver layer

15 to 70 (1 to 1.75 mm) weight percent;
lower silver layer

15 to 70 (1.75 to 2.5 mm) weight percent.

d) 3 layers of silver:
upper silver layer

10 to 65 (1 to 1.5 mm) weight percent;
middle silver layer

10 to 65 (1.5 to 2 mm) wt%;
lower silver layer

10 to 65 (2 to 2.5 mm) weight percent.

The copper crystals are also arranged in layers in the catalyst. The number of Copper crystal layers, based on the number of silver crystal layers, can be greater than, equal to or preferred be smaller. One to two copper layers are advantageous, preferably one copper layer. If only one layer is used If a copper layer is used, it contains I bis in case a) 40, in case b) 0.5 to 40, preferably in both cases 2 to 30 percent by weight of all catalyst particles Grain sizes from 0.2 to 0.75 mm. If you use 2 copper layers, then they are conveniently located in the lower part 0.5 to 39.5, preferably 1 to 29 percent by weight of all catalyst particles and im upper part 0.5 to 39.5, preferably 1 to 29 weight percent of all catalyst particles. The particles of the lower part of the layer have grain sizes of 0.4 to 0.75, those of the upper part of the layer 0.2 to 0.4 mm.

The copper crystal layers can be individually or several together or above and / or in unity each silver crystal layer can be arranged. It is advisable to use only one or 2 copper layers and places them above and / or below the upper part of the silver layer. If the upper part of the upper layer has several expediently 2 or 3 silver layers, then preferably 2 copper layers are used . above and below the uppermost silver layer of the upper silver layer part or, more advantageously, only a copper layer (counting from top to bottom) overlying the topmost silver layer

The layering of each individual silver or copper layer and, if necessary, each Cu / Sn / P particle layer is mostly regular, so that the layer thickness of the individual layer extends across the entire layer is the same in these cases, the layer thickness depends directly on the aforementioned weight

25th

30th

35

40

45

50

divide the total catalyst and the respective grain size of the particles. But you can also do an irregular one Layering of all or more layers or expediently a silver or copper layer or Make Cu / Sn / P particle layer, e.g. B. in the middle, on the sides or advantageously on the edge of the layer give up the bulk of the catalyst particles and, accordingly, only a smaller residual amount on the Spread the rest of the layer. In a preferred embodiment, several individual layers or advantageously a single layer only at the edge of the catalyst zone in the form of an annular or ring-shaped one Layer with flat top and bottom of the layer (ring layer) on the respective underlying, regularly arranged layer with regular layer thickness abandoned. The following is advantageous Arrangement: A ring layer is placed on the edge of the upper layer (layer 1) of the catalyst; suitably the diameter of the annular layer is, i. H. the difference in diameter of the cross section of the total catalyst and the inside width of the layer ring, the 100th to the 10th part of the catalyst diameter and thus the diameter of the upper, regular layer. The arrangement is particularly preferred, such a ring layer of the upper layer (layer 1) is not but rather to be placed underneath and thus put on the underlying layer (layer 2). on in this way, ring layer and layer 1 or ring layer, layer 1 and layer 2 acquire the shape of one flat bowl with an upturned rim. If the upper layer part contains several, e.g. B. 2 or 3 layers, so the ring layer of each layer of the upper layer part can be underlaid accordingly, z. More colorful Layer 2 or 3. Since reaction tubes or tubular reaction spaces are usually used as reactors such an edge lies on the outer tubular ring of the catalyst carrier or on the inner one Pipe wall.

A particularly advantageous catalyst has the following composition, with layer 3 as Ring layer Silver crystals with a ring diameter which is 60th of the diameter of the catalyst corresponds, formed and underlaid layer 2 and thus layer 4 is placed:

Layer 1 (copper layer):

10.7% by weight of the catalyst with particles of the

Grain size 0.2 - 0.4 mm
Layer 2 (copper layer):

103% by weight of the catalyst with particles of the

Grain size 0.4-0.75 min.
Layer 3 (silver layer):

13.4% by weight of the catalyst with particles with a grain size of 0.2-0.75 mm

Layer 4 (silver layer):

5.3% by weight of the catalyst with particles of grain size 0.75-1 mm «·

Layer 5 (lowest silver layer):

60.3% by weight of the catalyst with particles of grain size 1-2.5 mm.

The preferred embodiment is b). Here, 3 or more, preferably 3 to 9, silver layers become one

ίο or more copper layers, preferably one copper layer and one or more Cu / Sn / P particle layers, preferably one Cu / Sn / P particle layer for production of the total catalyst used.

In embodiment b), one or more layers (Cu / Sn / P particle layers) are used by catalyst particles with 70 to 99 percent by weight copper, 0.9 up to 20 percent by weight tin and 0.1 to 10 percent by weight phosphorus, based on the weight of these Particles on these elements, used advantageously 1 to 2 layers, especially one layer. Appropriate one or two Cu / Sn / P particle layers are placed on top of the total catalyst as the top layer or top 2 Layers on. Catalyst particles containing 90 to 97 percent by weight of copper and 2.9 to 7 percent by weight are preferred Tin and 0.1 to 3 percent by weight phosphorus, based on the weight of these particles on them Elements, included. The metals can be used as such or as oxides, phosphorus as phosphoric acid, Phosphate or as an oxide. Correspondingly, the particles can be used as a mixture of the aforementioned individual substances and / or as a mixture of compounds with one another such as phosphoric acid, copper oxide, tin oxide: they are advantageous in the usual way, for. B. by mixing the components, advantageously the aforementioned Connections made in a kneader. The aforementioned percentages by weight of the 3 components are calculated from the content of these 3 elements in the particles and refer to the Total weight of the particles of these 3 elements, without reference to the actual constitution of the Compounds that make up the particle. If only one layer is used, it has 0.5 to 10, preferably 2 up to 6 percent by weight of the catalyst with particles having a grain size of 0.2 to 0.75 mm. In the case of 2 layers Catalyst particles are in the lower part from 0.25 to 9.75, preferably from 1 to 5 percent by weight of all Catalyst particles and in the upper part 0.25 to 9.75, preferably 1 to 5 percent by weight of all catalyst particles. The particles of the lower layer part have

so grain sizes from 0.4 to 0.75, those of the upper part of the layer 0.2 to 0.4 mm. Regarding layer parts, number of layers, Stratification, weight differences and grain sizes of the silver and copper layers, the aforementioned general and preferred values and specifications apply. Preferred are the following layer arrangements:

Number of layers layers
(from top to
below) are counted Contains as
Crystals or part
Chen Ag or Cu
or Cu / Sn / P Weight percent
catalyst
from of the total
until Grain size in
mm
from until 5 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 3 Ag δ 50 0.2 0.75 4th Ag 2 30th 0.75 1 5 Ag 30th 85 1 2.5

continuation

ίο

Number of layers

Layers counted (from top to bottom)

Contains Ag or Cu as crystals or particles or Cu / Sn / P

Weight percent of the total grain size in

catalyst mm

from to from

Cu / Sn / P

Cu

Ag

Ag

Ag

Ag

10 40 50 30 70 70

0.2

0.2

0.2

0.75

1.75

Cu / Sn / P

Cu

Ag

Ag

Ag

Ag

Ag

10 40 50 29 29 70 70

0.2

0.2

0.2

0.75

0.9

1.75

1 2 3 4 5 6 7

1 2 3 4 5 6 7

Cu / Sn / P

Cu

Ag

Ag

Ag

Ag

Ag

Ag

Cu / Sn / P

Cu

Ag

Ag

Ag

Ag

Ag

Ag

Ag

10 40 50 29 29 65 65 65

10

40

50

28.7

28.7

28.6

65

65

65

0.2

0.2

0.2

0.75

0.9

1.5

0.2

0.2

0.2

0.75

0.8

0.9

1.5 2

10

1 2 3 4 5 6 7 8 9 10

Cu / Sn / P

Cu

Ag

Ag

Ag

Ag

Ag

Ag

Ag

Ag

10

40

46

46

28.7

28.7

28.6

65

65

65

0.2

0.2

0.2

0.4

0.75

0.8

0.9

1.5

. -i Jt.

continuation

Number of layers

layers
(from top to
below) are counted

Contains Ag or Cu or Cu / Sn / P as crystals or particles

Weight percent of the total grain size in

catalyst mm

from to from

until

9
10
11

Cu / Sn / P

Cu

Ag

Ag

Ag

Ag

Ag Ag Ag Ag Ag

10
40
45
45
44
28.7

28.7

28.6

65

65

65

0.2 0.2 0.2 0.4 0.6 0.75

0.8

0.9

1.5

0.75

0.75

0.4

0.6

0.75

0.8

0.9

1.5

2.5

10

11th

12th

Cu / Sn / P

Cu

Cu

Ag Ag Ag Ag Ag Ag Ag Ag Ag

10

39.5

39.5

45

45

44

28.7

28.7

28.6

65

65

65

0.2

0.2

0.4

0.2

0.4

0.6

0.75

0.8

0.9

1.5

0.75

0.75

0.4

0.6

0.75

0.8

0.9

1.5

10

11th

12th

13th

Cu / Sn / P

Cu / Sn / P

Cu

Cu

Ag

Ag

Ag

Ag

Ag

Ag

Ag

Ag

Ag

9.75
9.75

39.5

39.5

45

45

44

28.7

28.7

28.6

65

65

65

0.2

0.4

0.2

0.4

0.2

0.4

0.6

0.75

0.8

0.9

1.5

0.4

0.75

0.4

0.75

0.4

0.6

0.75

0.8

0.9

1.5

2.5

The aforementioned catalysts are particularly preferred with 5,6 and 7 layers.

The catalyst is expediently loaded with 0.2 to 2.5 t, in particular 0.6 to 2 t, of vaporous starting material II per m ^{2 of} catalyst bed cross-section per hour. For large-scale implementation, catalyst bed diameters of at least 0.05, expediently 0.1 to 3 meters, are preferably used. Residence times of the reaction from 0.001 to 1, preferably in the case

the production of methoxyacetaldehyde 0.01 to 0.6, in the case of the production of methoxyacetone 0.01 to 0.5 Minutes are advantageous. The residence time is based on the reaction zone without a catalyst and so on calculated The reaction space of an empty reactor pipe can serve as a basis for calculation.

The reaction is expediently at a temperature of 450 to 700 ⁰ C, preferably at a temperature of 475 to 650 ⁰ C, in particular 500 to

625 ° C, without pressure or under pressure, discontinuous or preferably carried out continuously. You can implement in the absence of additional solvents; It is expedient to use water, advantageously in an amount of from 5 to 40, in particular from 10 to 20 Percentage by weight, based on starting material II. Likewise secondary substances from the production of the starting materials II can still be mixed with these, e.g. Am an amount of up to 10 percent by weight, based on starting material II.

The oxidation can be carried out as follows: In an evaporation unit, e.g. B. a falling film evaporator, are entered individually or in a mixture of starting material II and optionally water and evaporated, expediently at 70 to 180 ° C. Then is the gas mixture of vaporous starting material II, air, optionally inert gas and water vapor passed through the catalyst in the aforementioned amounts at the reaction temperature generally at pressures between 0.5 and 3 bar, preferably between 0.8 and 1.8 bar, continuously The silver catalyst is expediently brought to a temperature before the start of the process heated from 250 to 500, preferably from 380 to 45U ° C. The beginning of the exothermic reaction is expediently determined by adding air to the starting mixture admits and checks the temperature change in the catalytic converter. If the reaction sets in, one observes immediately an increase in temperature, otherwise the temperature will decrease due to the supply of cold air. The temperature is expediently measured in the catalytic converter by means of thermocouples. From the beginning of the reaction in general, the air is fed continuously to the vaporous starting mixture, if appropriate while passing through the sump of the evaporation unit. It is advantageous to have the catalyst zone leaving reaction gases to cool within a short time, z. B. to temperatures of 20 to 160 ° C. The main part of the end product I is condensed in this way. The cooled gas mixture is then expediently a Absorption tower supplied in which the end product I with a suitable solvent such as dimethylformamide, Dimethyl sulfoxide, acetone, methanol or water and mixtures thereof and / or in the initially charged Condensate from previous reactions, advantageously in countercurrent, is washed from the gas mixture. the end The end product I is then condensate and the absorbates in the usual manner, for. B. by distillation, isolated.

The etherified hydroxyaldehydes and hydroxyketones which can be prepared by the process of the invention are valuable raw materials for the production of dyes, pesticides, plastics, Fragrances. With regard to the use, reference is made to the aforementioned publications.

The parts given in the following examples are parts by weight.

Example 1 (drawing)

A system is used, consisting of an evaporator (1), a vertical tubular reactor (2), a downstream cooler (3) and an absorption system (4). The evaporator is through the line (5) connected to the tubular reactor. The line can be heated up to the reactor. The catalyst layer lies below the reactor head, further down follows the cooling zone (3), which is connected to the through line (7)

Absorption system (4) is connected The condensate occurring in the cooling zone (3) is via line (6) led to line (11) The absorption system (4) form four absorption columns arranged in a cascade with cooling. The four columns are 15 mm Ceramic Pall rings filled The exhaust gas escapes via line (8).

In the reactor (2) is a catalyst (1.63 parts) made of silver crystals (Ag), copper crystals (Cu) as well Catalyst particles (94.1 percent by weight Cu, 4.9 percent by weight Sn, 1 percent by weight P = Cu / Sn / P) of the following composition:

15th Particle Share in Grain size £ art catalyst Weight Ϊ percent mm " ²⁰ shift 1 Cu / Sn / P 2.7 0.2 to 0.75 f (above) I. Layer 2 ■ Cu 18.8 0.2 to 0.75 j Layer 3 Ag 13.2 0.2 to 0.75 \ 25 shift 4 Ag 14.7 0.75 to 1.0 \ Layer 5 Ag 50.6 1.0 to 2.5 1 (below)

The diameter of the catalyst layer is 0.15 Meters, the total thickness of the catalyst before the start of the reaction 22 millimeters.

The catalyst is heated by passing hot nitrogen at a temperature of 38O ⁰ C. In the evaporator via line (10) 15 parts Äthyleng'.ykoimonomethyläther be entered and heated to 80 ⁰ C. Now 0.95 parts of air per hour are introduced into the evaporator via line (9) and the contents of the evaporator are further heated to 110.degree.

The amount of air is then increased to 1.4 parts per hour, the temperature of the catalyst increasing begins to rise. With the start of the reaction, recognizable by the rising catalyst temperature stopped the nitrogen supply within 3 hours, the amount of air to 14.6 parts of air per hour, and at the same time via line (10), evaporator (1) and line (5) the amount passed through the catalyst of ethylene glycol monomethyl ether to 14.1 parts per hour (corresponding to a space velocity over the catalyst of

0.8 tons of ethylene glycol monomethyl ether per hour and square meter of catalyst bed cross-section) and added 9.3 parts of water per hour. At a pressure upstream of the catalyst of 1.04 bar, a catalyst ^{temperature of 575 °} C. is established. The reaction mixture is then cooled to 94 ° C. in the cooling zone of the reactor (3). The absorption (4) itself takes place in 4 stages in countercurrent in the form of gas scrubbing. 11.5 parts of water per hour at a temperature of 25 ° C. are introduced into the cascade (4) and used as the absorption liquid via line (12). Over the course of 720 hours, 10,152 parts of ethylene glycol monomethyl ether are passed over the catalyst. A total of 2,274 parts of unreacted ethylene glycol monomethyl ether and 5,850 parts of methoxyacetaldehyde are obtained via line (11). The conversion is 77.6 percent, the yield of methoxyacetaldehyde 76.4% of theory, based on the converted ethylene glycol monomethyl ether.

Example 2

Analogously to Example 1, a mixture of 56.3 parts of 1,2-propylene glycol monomethyl ether and 14.1 parts of water with 58.5 parts of air within 5 hours at 600 ^° C. and 1.09 bar over a catalyst (0.79 parts) the following composition:

Particle Share in Grain size art catalyst Weight percent mm Layer 1 Cu 2.5 0.2 to 0.75 (top) Layer 2 Ag 12th 0.2 to 0.4 Layer 3 Ag P., 5 0.4 to 0.75 Layer 4 Ag 6th 0.75 to 0.9 Layer 5 Ag 6th 0.9 to 1.0 Layer 6 Ag 30th 1 to 1.75 Layer 7 Ag 31 1.75 to 2.5 (lowest)

0.34 part of unreacted propylene glycol methoxyacetone is obtained, 69.9% of theory, based on monoinethyl ether and 38.25 parts of methoxyacetone. The converted propylene glycol monomethyl ether. Conversion is 99.4 percent, the yield

1 sheet of drawings 130 218/276

Claims (1)

Claim: Process for the preparation of aliphatic hydroxycarbonyl compounds etherified with aliphatic groups by catalytic oxidation of hydroxy alcohols in the presence of metal catalysts, characterized in that aliphatic groups are etherified with aliphatic groups Hydroxy alcohols in the presence of a catalyst with a total layer thickness of 5 to Millimeter and a) 3 or more layers of silver crystals, some of the layers of silver crystals being 30 to 85 Percentage by weight of the catalyst with particles of grain size 1 to 2.5 mm, part of the Layers of silver crystals 2 to 30 percent by weight of the catalyst with particles of the grain size 0.75 to 1 mm and the remaining part of the layers of silver crystals 8 to 50 percent by weight of the catalyst with particles of grain size 0.2 to 0.75 mm, and one or more layers of copper crystals that make up 1 to 40 percent by weight of the catalyst with particles contain the grain size 0.2 to 0.75 mm, or b) 3 or more layers of silver crystals, some of the layers of silver crystals being 30 to 85 Percentage by weight of the catalyst with particles of grain size 1 to 2.5 mm, part of the Layers of silver crystals from 2 to 30 percent by weight of the catalyst with particles of the grain size 0.75 to 1 mm and the remaining part of the layers silver crystals 8 to 50 percent by weight of the catalyst with particles of grain size 0.2 to 0.75 mm, and one or more layers of copper crystals that make up 0.5 to 40 percent by weight of the catalyst with particles the grain size 0.2 to 0.75 mm, and one or more layers of catalyst particles with 70 to 99 percent by weight copper, 0.9 to 20 percent by weight tin and 0.1 to 10 Weight percent phosphorus, based on the weight of these particles in these elements, said layers comprising catalyst particles from 0.5 to 10 percent by weight of the catalyst Contain particles with a grain size of 0.2 to 0.75 mm, oxidized at a temperature of 450 to 700 ° C. 15th 20th 25th 30th 35 40 45 50 The invention relates to a new process for the production of aliphatic groups with aliphatic groups etherified hydroxycarbonyl compounds by oxidation of hydroxy alcohols in the presence of a Metal catalyst, consisting of one or more layers, each with a certain weight and each Particles of a certain grain size and a certain total layer thickness consists, with as catalyst metals Silver and copper and possibly also copper / tin / phosphorus can be used. It is from Houben-Weyl, Methods of Organic Chemie, Volume 7/1, pages 166 and 167 known that compounds other than the primary alcohol group still contain ether groups, usually dehydrate themselves to the aldehydes only with very moderate yields permit. In order to avoid cleavage reactions, one must either work at the lowest temperature limit or as in the case of the dehydrogenation of tetrahydrofurylcarbinol to tetrahydrofuran-2-aldehyde in a implement relatively high temperature and shortest residence time on the catalyst. So is used for the production of the Methoxyacetaldehyde a hydrotreated copper oxide catalyst and a reaction temperature of 300 ° C used In the same way, you can also produce ethoxy and butoxyacetaldehyde. However, the yields are even worse here. A job in Zh. Prikl. Khim. (Leningrad) 1970, volume 43, pages 1132-1136 (English text, pages 1137-1140) describes the reaction of methylglycol with air Silver wire spirals as a catalyst at temperatures from 380 to 578 ° C and with yields from 24.3 to 58 Percent, based on the starting material. Corresponding reactions with butyl glycol at 463 to 488 ° C were made carried out. Reaction temperatures of 465 to 475 ° C. are found to be advantageous in both cases viewed. The disadvantage of this process is that, despite the use of a vacuum and with the addition of the same amount of nitrogen as air, only a maximum of 58 percent yield can be achieved. It is also known (Houben-Weyl, loc. Cit, volume 7 / 2a. Pages 699 to 776) to catalytically dehydrate secondary alcohols to ketones or to oxidize them with air. In general, hydrogenation catalysts are also used as catalysts as dehydrogenation catalysts proposed, in particular the aforementioned catalysts of aldehyde syntheses (loc. Cit., Page 700). Man generally works for dehydrogenation in the gas phase between 180 and 400 ° C., predominantly between 200 and 250 ° C. For the synthesis of l-methoxy-2-oxo-propane, the oxidation also leads Chromic acid / sulfuric acid / water mixtures only lead to a yield of 29 percent (Houben - Weyl, loc. Cit, Volume 7 / 2a, pages 722 to 724). It is known from US Pat. No. 21 70 855 that alkoxyisopropanols are in the gas phase with air in Presence of metal oxides such as silver, copper, nickel and cobalt oxide or of metal catalysts such as copper, copper / chromium, chromium, silver, cobalt and nickel oxidized to alkoxyacetones As reaction temperatures 250 to 300 ° C are specified. If the process is carried out on an industrial scale, yields of 9.8 to 33.7 percent are obtained. All of these processes are simple and economical in terms of operation, yield and purity of the end product unsatisfactory. It has now been found that aliphatic hydroxycarbonyl compounds etherified with aliphatic groups by catalytic oxidation of hydroxy alcohols in the presence of metal catalysts advantageously obtained when aliphatic, etherified with aliphatic groups hydroxy alcohols in the presence a catalyst with a total layer thickness of 5 to 100 millimeters and