DE2758124A1 - Aliphatic alkoxy substd. carbonyl cpds. prodn. - by oxidising corresp. hydroxy-ether over metal catalyst, useful as intermediates for dyes, pesticides, plastics and perfumes - Google Patents

Abstract

Prodn. of aliphatic hydroxycarbonyl cpds. (I) etherified by aliphatic gps. comprises oxidn. of etherified hydroxyalcohols (II) at 450-700 degrees C over a catalyst bed of total thickness 5-100 mm. This bed has >=3 layers of Ag crystals: (a) a layer of particle size 1-2.5 mm (30-85 wt.% of the catalyst); (b) a layer of 0.75-1 mm (2-30 wt.%); and (c) a layer of 0.2-0.75 mm (8-50 wt.%); and >=1 layer of Cu crystals of particle size 0.2-0.75 mm making up 1-40 wt.% of the catalyst. Opt. there is also >=1 layer of particles of size 0.2-0.75 mm comprising 70-99 wt.% Cu, 0.9-20 wt.% Sn and 0.1-10 wt.% P, making up 0.5-10 wt.% of the catalyst.

Description

Process for the preparation of aliphatic, with aliphatic

Groups Etherified Hydroxycarbonyl Compounds The invention relates to a new process for the preparation of aliphatic, with aliphatic groups etherified hydroxycarbonyl compounds by oxidation of hydroxy alcohols in Presence of a metal catalyst composed of one or more layers of each certain weight and each with particles of a certain grain size and a certain Total layer thickness consists, with the catalyst metals silver and copper and optionally copper / tin / phosphorus can also be used.

It is from Houben-Weyl, Methods of Organic Chemistry, Volume 7/1, Pages 166 and 167 disclose that compounds other than the primary alcohol group still contain ether groups, usually only with very moderate yields to the aldehydes let it dehydrate. In order to avoid cleavage reactions, one must either work on the lowest one Working temperature limit or as in the case of the dehydrogenation of Tetrahydrofurylcarbinois to tetrahydrofuran-2-aldehyde at a relatively high temperature and a very short residence time convert on the catalyst. So is used for the production of methoxyacetaldehyde hydrotreated copper oxide catalyst 8Dr and a reaction temperature of 3000C used. Ethoxy- and butoxyacetaldehyde can also be used in a corresponding manner produce. However, the yields are even worse here.

A job in Zh. Prikl. Khim. (Leningrad) 1970, volume 43, pages 1 132 - 1 136 (English text, page 1 137 - 1 140) describes the conversion of methylglycol with air on silver wire spirals as a catalyst at temperatures from 380 to 5780C and with yields of 24.3 to 58 percent, based on the starting material. Appropriate Reactions with butyl glycol at 463 to 48800 were carried out. Reaction temperatures from 465 to 4750C are considered beneficial in both cases. Disadvantageous is in this process that despite the use of vacuum and with the addition of the same Amounts of nitrogen such as air only achieve a maximum yield of 58 percent.

It is also known (Houben-Ileyl, loc. Cit., Volume 7 / 2a, pages 699 to 776) to dehydrate secondary alcohols catalytically or with To oxidize air. The catalysts used are generally hydrogenation catalysts also proposed as dehydrogenation catalysts, in particular those mentioned above Catalysts for aldehyde syntheses (loc. Cit., Page 700). One works in general in the case of dehydrogenation in the gas phase between 180 and 40,000, mainly between 200 and 250 ° C. For the synthesis of 1-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. 2,170,855 that one can use alkoxyisopropanols in the gas phase with air in the 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. The reaction temperatures are 250 specified up to 30000. If the process is carried out on an industrial scale, it is obtained yields of 9.8 to 3.7 percent.

All of these procedures are simple and economical in terms of their convenience Method of operation, yield and purity of the end product unsatisfactory.

It has now been found that one can aliphatic with aliphatic groups Etherified hydroxycarbonyl compounds by catalytic oxidation of hydroxy alcohols in the presence of metal catalysts advantageously obtained when aliphatic, Hydroxy alcohols etherified with aliphatic groups in the presence of a catalyst with a total layer thickness of 5 to 100 millimeters and a) 3 or more layers of silver crystals, some of the layers being silver crystals 30 up to 85 percent by weight of the catalyst with particles of grain size 1 to 2.5 mm, a portion of the layers of silver crystals are 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 silver crystals 8 to 50 percent by weight of the catalyst with particles of particle size 0.2 to 0.75 mm, and one or more layers of copper crystals, which are 1 to 40 percent by weight of the catalyst with particles of grain size 0.2 to 0.75 mm, or b) 3 or more layers of silver crystals, some of the layers being silver crystals 30 to 85 percent 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 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 particle size 0.2 to 0.75 mm, and one or more layers of copper crystals that are 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 on the weight of these particles on these elements, these layers being catalyst particles 0.5 to 10 percent by weight of the catalyst with particles of particle size 0.2 to 0.75 mm, oxidized at a temperature of 450 to 7000C.

In the event that methyl glycol is used, the reaction can be represented by the following formulas: Compared 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 products and service life of the catalyst. The life of the catalyst is usually at least 30 days in the case of methoxyacetaldehyde.

All of these beneficial results are in terms of the state of technology, especially the teaching of Houben-Weyl, surprising, because one In view of the high temperatures according to the invention, would have at least one essential Expect deterioration in yield and considerable formation of decomposition products should. With regard to the in Zh. Prikl. Khim. procedures described need Water or inert gas not to be added. The elaborate way of working under Vacuum and with special catalyst treatment is avoided. High specific Catalyst loads, e.g. 0.4 - 2.5 t / m2 catalyst bed cross-section compared to hour 0.15 t / m2 catalyst bed cross-section. Hour (Zh. Prikl. Khim.), Can be achieved will.

Compared to that described in US Pat. No. 2,170,855 Processes are higher in yield and conversion.

The aliphatic hydroxycarbonyl compounds etherified with aliphatic groups are expediently those end products of the formula and accordingly, as aliphatic hydroxy alcohols etherified with aliphatic groups, such starting materials of the formula into consideration, in which the individual radicals R1 can be identical or different and each represent a hydrogen atom, an aliphatic radical or the radical R3-o-, where at least one radical R1 denotes the radical R3-o-, R2 denotes a hydrogen atom or the radical stands, x and z can be identical or different and each represent 0 or an integer, R3 denotes an aliphatic radical, the individual radicals R4 can be identical or different and each denotes a hydrogen atom, an aliphatic radical or the radical R3-o- , wherein R3 has the aforementioned meaning. Preferred starting materials II and correspondingly preferred end products I are those in whose formulas the individual radicals R1 can be identical or different and each denotes a hydrogen atom or an alkyl radical having 1 to 5 carbon atoms or the radical R3-0-, where at least one radical R1 denotes R3-o- denotes, R2 denotes a hydrogen atom or the remainder R3 denotes an alkyl radical having 1 to 5 carbon atoms, R4 denotes a hydrogen atom or an alkyl radical having 1 to 5 carbon atoms or the radical R) -O-, where R3 has the preferred meaning mentioned above, x and z are identical or different and can each mean 0 or an integer, in particular 0, 1 or 2. The abovementioned radicals can also be substituted by groups which are inert under the reaction conditions, for example alkyl groups having 1 to 4 carbon atoms.

There are e.g. possible starting materials II: methyl, ethyl, n-propyl, Isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl-ethylene glycol; appropriate Propylene (1,2) -, propylene (1,3) -, butylene (1,2) -, butylene (1,3) -, butylene42,3) -, Butylene (1,4), isobutylene, pentylene (1,5), hexylene (1,6) glycol ethers; in a a-position to the hydroxyl group by 2 or 3 substituted methoxy groups ethanol, n-propanol, 2-hydroxypropane, n-butanol, 2-hydroxybutane, isobutanol and corresponding diethyl or triethyl (a) ethers; in a-, a'-, ß-, B'-, a, «'-, B, B'-, a, B'-, ß, a'-position to the hydroxyl group correspondingly several times or advantageously simply, twice or three times by the methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, sec-butoxy, isobutoxy group-substituted 2-hydroxypropane, 2-hydroxybutane, 2-hydroxypentane, 3-hydroxypentane.

Both pure oxygen and also use gases containing free oxygen, especially air. Oxygen, usually in the form of air, and starting material II are expediently in the molar ratio from 0.25 to 0.8, in particular from 0.35 to 0.6 mol of oxygen per iuiol starting material II applied. It is not necessary to use inert gas, but on the other hand it is a problem not even the implementation.

If necessary, hot inert gases, advantageously nitrogen, can be used or low-soot combustion gases that contain no catalyst poisons, e.g. from a temperature of 600 to 8000C, heat the catalyst.

The total layer thickness of the catalyst is 5 to 100, preferably 10 to 30 mm. The catalyst particles are in the form of silver crystals in the catalyst of the reactor, which is usually set up vertically, depending on the grain size arranged in an upper, middle or lower part of the overall layer.

The starting mixture of steam from starting material II and oxygen or air is generally passed from top to bottom, so that the upper layer (upper layers) simultaneously means the part facing the starting mixture. For reactors of a different design or a different management of the output mixture apply all information in the description about the upper (lower) part of the catalytic converter for the corresponding, the starting mixture (the stirred reaction mixture) facing Part, e.g. in the case of horizontally arranged reactors for the front (rear) part of the catalyst. The following information regarding the proportion in percent by weight all Catalyst particles refer to the total weight of the catalyst, i.e. 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 to 35 percent by weight of all catalyst particles. The particles of the lower part of the layer have grain sizes from 1 to 2.5, those of the middle layer part from 0.75 to 1, the of the upper layer part 0.2 to 0.75 mm. Each silver layer part can consist of one or several layers, preferably of 1, 2 or 3 layers. Preferred is a 4 to 7 silver layer catalyst, especially a 4 or 5 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, so have its lower silver layer preferably a proportion of 4 to 46 percent by weight and particles a grain size of 0.4 to 0.75mm and its upper silver layer correspondingly one Weight fraction of 4 to 46 percent by weight and particles with a grain size of 0.2 to 0.4 mm. If there are 3 layers of silver in the upper part of the silver layer, there are with In relation 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 up to 0.6 mm); lower silver layer 2 to 44 (0.6 to 0.75 mm) weight percent. Corresponding are in the middle part of the silver layer with reference to weight fraction (grain size of the particles) preferred: a) 2 silver layers: upper silver layer 1 to 29 (0.75 to 0.9 mm) wt. lower silver layer 1 to 29 (0.9 to 1 mm) wt.%.

b) 3 layers of silver: upper layer of silver 0.7 to 28.7 (0.75 to 0.8 mm) wt. middle silver layer 0.7 to 28.7 (0.8 to 0.9 mm) wt .; lower silver layer 0.6 to 28.6 (0.9 to 1 mm) wt.

For the lower part of the silver layer, the following are preferred: c) 2 silver layers: upper silver layer 15 to 70 (1 to 1.75 mm) wt. lower silver layer 15 bis 70 (1.75 to 2.5 mm) wt.

d) 3 silver layers: upper silver layer 10 to 65 (1 to 1.5 mm) Wt%; 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 in layers in the catalyst arranged. The number of copper crystal layers can, based on the number of Silver crystal layers, larger, equal or preferably smaller. Advantageous are one to 2 copper layers, preferably one copper layer. Will only be one If the copper layer is used, it contains 1 to 40 in case a) and 0.5 to in case b) 40, preferably 2 to 30 percent by weight of all catalyst particles in both cases with grain sizes from 0.2 to 0.75 mm. If you use 2 copper layers, then there are expediently in the lower part 0.5 to 39.5, preferably 1 to 29 percent by weight all catalyst particles and in the 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 above and / or be arranged below each silver crystal layer. Used appropriately just one or two layers of copper and place them above and / or below the upper part of the silver layer. If the upper part of the silver layer has several, expediently 2 or 3 layers of silver, 2 layers of copper are preferably used, which are above and below the uppermost silver layer of the upper silver layer part, or more advantageous only a copper layer (counting from top to bottom) over the uppermost silver layer lies.

The layering of each individual silver or copper layer and, if applicable Each Cu / Sn / P particle layer is also mostly regular, so that the layer thickness of the individual layer is the same over the entire layer cross-section. In these In some cases, the layer thickness depends directly on the aforementioned proportions by weight of 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 a Cu / Sn / P particle layer, e.g. in the middle, on the sides or advantageously at the edge of the layer give up most of the catalyst particles and accordingly distribute only a small amount of residue over the rest of the layer.

In a preferred embodiment, several individual layers are used or advantageously a single layer only at the edge of the catalyst zone in the form a ring-shaped or ring-shaped layer with a flat top and bottom of the layer (Ring layer) on the respective underlying, regularly arranged layer with regular layer thickness. The following arrangement is advantageous: The upper one Layer (layer 1) of the catalyst, a ring layer is placed on the edge; expedient is the Diameter of the annular layer, i. the difference between the diameter of the cross section of the total catalyst and the clear Width of the layer ring, the 100th to the 10th part of the catalyst diameter and thus the diameter of the upper, regular layer. Particularly preferred is the arrangement, such a ring layer of the upper layer (layer 1) is not to put on but to be placed underneath and thus the layer underneath (layer 2) put on. In this way, ring layer and layer 1 or ring layer gain Layer 1 and Layer 2 have the shape of a flat bowl with an upwardly curved rim.

If the upper part of the layer contains several, e.g. 2 or 3 layers, see below the ring layer can underlay each layer of the upper layer part accordingly e.g. under layer 2 or 3.

Since the reactors are usually reaction tubes or tubular reaction spaces are used, such an edge is on the outer tubular ring of the catalyst carrier or on the inner pipe wall.

A particularly advantageous catalyst has the following composition, with layer 3 as a ring layer silver crystals with a ring diameter that corresponds to 60th part of the catalyst diameter corresponds, formed and layer 2 underlaid and thus layer 4 is placed: Layer 1 (copper layer): 10.7% by weight of the catalyst with particles with a grain size of 0.2-0.4 mm Layer 2 (copper layer): 10.3% by weight of the Catalyst with particles of grain size 0.4 - 0.75 mm Layer 3 (silver layer): 13.4 wt. Of the catalyst with particles of grain size 0.2-0.75 mm Layer 4 (silver layer): 5.3 wt. Of the catalyst with particles of grain size 0.75 - 1 mm Layer 5 (silver layer): 60.3% by weight of the catalyst with part (lowest) surfaces of grain size 1 - 2.5 mm.

The preferred embodiment is b). Here are 3 or more, preferably 3 to 9, silver layers, one or more copper layers, preferably one copper layer and one or more Cu / Sn / P particle layers, preferably one Cu / Sn / P particle layer used to produce the overall catalyst.

In embodiment b), one or more layers (Cu / Sn / P particle layers) of catalyst particles with 70 to 99 weight percent copper, 0.9 to 20 weight percent Tin and 0.1 to 10 weight percent phosphorus based on the weight of these particles on these elements, advantageously 1 to 2 layers, especially one Layer. One or two Cu / Sn / P particle layers are expediently placed in the overall catalyst as the top layer or top 2 layers. Catalyst particles are preferred, the 90 to 97 weight percent copper, 2.9 to 7 weight percent tin and 0.1 to 3 percent by weight of phosphorus, based on the weight of these particles in these Blementen, contain. 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, are present; they become advantageous in the usual way, for example by mixing of the components, advantageously the aforementioned compounds, prepared in a kneader. The aforementioned percentages by weight of the 3 components are therefore calculated from the Content of these 3 elements in the particles and are based on the total weight of the particles in these 3 elements, without reference to the actual constitution of the compounds that make up the particle. If you only use one layer, it has this 0.5 to 10, preferably 2 to 6 percent by weight of the catalyst with particles the grain size 0.2 to 0> 75 mm. In the case of 2 layers there are catalyst particles in the lower part 0.25 to 9.75, preferably 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 Grain sizes of 0.4 up to 0.75> that of the upper layer part 0.2 to 0.4 mm. Regarding layer parts, Number of layers, layers, proportions by weight and grain sizes of the silver and copper layers the aforementioned general and preferred values and information apply. Preferred are the following layer arrangements: Layers- contains layers as% by weight of the grain size number (from top to crystals or total catalyst mm below) counted Particle sators Ag or Cu or Cu / Sn / P from to from to 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 5 3 Ag 8 50 0.2 0.75 4 Ag 2 30 0.75 1 5 Ag 30 85 1 2.5 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 6 3 Ag 8 50 0.2 0.75 4 Ag 2 30 0.75 1 5 Ag 15 70 1 1.75 6 Ag 15 70 1.75 2.5 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 7 3 Ag 8 50 0.2 0.75 4 Ag 1 29 0.75 0.9 5 Ag 1 29 0.9 1.0 6 Ag 15 70 1 1.75 7 Ag 15 70 1.75 2.5 Layers contains layers as% by weight of the grain size number (from top to crystals or total catalyst mm below) counted particles sators Ag or Cu or Cu / Sn / P from to from to 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 3 Ag 8 50 0.2 0.75 8 4 Ag 2 29 0.75 0.9 5 Ag 1 29 0.9 1 6 Ag 10 65 1 1.75 7 Ag 10 65 1.5 2 8 Ag 10 65 2 2.5 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 3 Ag 8 50 0.2 0.75 9 4 Ag 0.7 28.7 0.75 0.8 5 Ag 0.7 28.7 0.8 0.9 6 Ag 0.6 28.6 0.9 1 7 Ag 10 65 1 1.5 8 Ag 10 65 1.5 2 9 Ag 10 65 2 2.5 Layers- Layers contains as% by weight of the grain size number (from top to crystals or total catalyst mm below) counted particles sators Ag or Cu or Cu / Sn / P from to from to 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 3 Ag 4 46 0.2 0.4 4 Ag 4 46 0.4 0.75 10 5 Ag 0.7 28.7 0.75 0.8 6 Ag 0.7 28.7 0.8 0.9 7 Ag 0.6 28.6 0.9 1 8 Ag 10 65 1 1.5 9 Ag 10 65 1.5 2 10 Ag 10 65 2 2.5 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 40 0.2 0.75 3 Ag 3 45 0.2 0.4 4 Ag 3 45 0.4 0.6 11 5 Ag 2 44 0.6 0.75 6 Ag 0.7 28.7 0.75 0.8 7 Ag 0.7 28.7 0.8 0.9 8 Ag 0.6 28.6 0.9 1 9 Ag 10 65 1 1.5 10 Ag 10 65 1.5 2 11 Ag 10 65 2 2.5 Layers Layers contains number as% by weight of the grain size (from top to crystals or total catalyst mm below) counted particles sators Ag or Cu or Cu / Sn / P from to from to 1 Cu / Sn / P 0.5 10 0.2 0.75 2 Cu 0.5 39.5 0.2 0.4 3 Cu 0.5 39.5 0.4 0.75 4 Ag 3 45 0.2 0.4 5 Ag 3 45 0.4 0.6 12 6 Ag 2 44 0.6 0.75 7 Ag 0.7 28.7 0.75 0.8 8 Ag 0.7 28.7 0.8 0.9 9 Ag 0.6 28.6 0.9 1 10 Ag 10 65 1 1.5 11 Ag 10 65 1.5 2 12 Ag 10 65 2 2.5 Layers-Layers contains as% by weight of the grain size number (from top to crystals or total catalyst mm below) counted particles sators Ag or Cu or Cu / Sn / P from to from to 1 Cu / Sn / P 0.25 9.75 0.2 0.4 2 Cu / Sn / P 0.25 9.75 0.4 0.75 3 Cu 0.5 39.5 0.2 0.4 4 Cu 0.5 39 , 5 0.4 0.75 13 5 Ag 3 45 0.2 0.4 6 Ag 3 45 0.4 0.6 7 Ag 2 44 0.6 0.75 8 Ag 0.7 28.7 0.75 0.8 9 Ag 0.7 28.7 0.8 0.9 10 Ag 0.6 28.6 0.9 1 11 Ag 10 65 1 1.5 12 Ag 10 65 1.5 2 13 Ag 10 65 2 2.5 The aforementioned are particularly preferred Catalysts 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 m2 of catalyst bed cross-section and Hour. Catalyst bed diameters are preferably used for large-scale implementation of at least 0> 05, expediently 0.1 to 3 meters. Dwell times for implementation from 0.001 to 1, preferably 0.01 in the case of the preparation of methoxyacetaldehyde up to 0.6 minutes, in the case of the preparation of methoxyacetone 0.01 to 0.5 minutes are advantageous. The residence time is based on the reaction zone without catalyst filling and so on calculated. As a basis for calculation, e.g.

serve as the reaction space of an empty reactor tube.

The reaction is expediently at a temperature of 450 to 7000C, preferably at a temperature of 475 to 6500C, in particular 500 to 6250C, carried out without pressure or under pressure, discontinuously or preferably continuously. You can implement in the absence of additional solvents; appropriately used one water, advantageously in an amount from 5 to 40, in particular from 10 to 20 Percentage by weight, based on starting material II the production of the starting materials II still be mixed with these, e.g. in one Amount 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. a falling film evaporator, starting material II and optionally water entered and evaporated, expediently at 70 to 1800C.

Then the gas mixture is made of vaporous starting material II, Air, optionally inert gas and steam in the abovementioned amounts at the reaction temperature passed through the catalyst. The process is generally carried out at pressures between 0.5 and 3 bar, preferably between 0.8 and 1.8 bar, continuously carried out. The silver catalyst is expediently activated before the start of the process heated to a temperature of 250 to 500, preferably from 380 to 450C. The beginning the exothermic reaction is expediently determined by adding air to the starting mixture admits and checks the temperature change in the catalytic converter. Starts the reaction one immediately observes an increase in temperature, otherwise the temperature becomes sink by the supply of cold air.

The temperature is expedient in the catalyst by means of thermocouples measured. From the start of the reaction, the air is generally passed in continuously to the vaporous starting mixture, if appropriate while passing it through the sump of the evaporation unit. It is advantageous for those that leave the catalyst zone Cooling reaction gases within a short time, e.g. to temperatures from 20 to 1600C. The main part of the end product I is condensed in this way. The cooled gas mixture is then expediently fed to an absorption tower in which the end product I with a suitable solvent such as dimethylformamide, dimethyl sulfoxide, acetone, Methanol or water and their mixtures and / or earlier in the submitted condensate Reactions, advantageously in countercurrent, is washed from the gas mixture.

From the condensate and the absorbates, the endstdff I is then in the usual way Way, e.g. by distillation.

The etherified hydroxyaldehydes which can be prepared by the process of the invention and hydroxyketones are valuable starting materials for the production of dyes, Pesticides, plastics, fragrances. Regarding 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 one Evaporator (1), a vertical tubular reactor (2), a downstream cooler (3) and an absorption system (4). The evaporator is through the line (5) with 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 through the line (7) is connected to the absorption system (4). That in the refrigerator section (3) Accumulating condensate is led to line (11) via line (6). The absorption system (4) form four absorption columns arranged in a cascade with cooling. The four Columns are filled with 15 mm Pall rings made of ceramic. Escapes via line (8) the exhaust.

A catalyst (1.63 parts) made of silver crystals is placed in the reactor (2) (Ag), copper crystals (Cu) and 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 entered: Particle type Proportion in the catalyst Grain size analyzer Weight percent mm Xcei t t 1 Cu / Sn / P 2.7 0.2 to 0.75 layer 2 Cu 18.8 0.2 to 0.75 layer 3 Ag 13.2 0.2 to 0.75 layer 4 Ag 14.7 0.75 to 1.0 layer 5 Ag 50.6 1.0 to 2.5 (bottom) The diameter of the catalyst layer is 0.15 meters, the total layer thickness of the catalyst before the start of the reaction 22 millimeters.

The catalyst is by bubbling hot nitrogen on a Heated temperature of 3800C. Be in the vaporizer over line (10) 15 parts of ethylene glycol monomethyl ether entered and heated to 80.degree. so 0.95 parts of air per hour are introduced into the evaporator via line (9) the contents of the vaporizer are further heated up to 1100C. After that, the amount of air increases 1.4 parts per hour increased, with the temperature of the catalyst increasing begins. With the start of the reaction, recognizable by the rising catalyst temperature, the nitrogen supply is stopped within 3 hours and the amount of air increases hourly 14.6 parts of air, and at the same time via line (10), evaporator (1) and Line (5) the amount of ethylene glycol monomethyl ether passed through the catalyst to 14.1 parts per hour (corresponding to a catalyst loading of 0.8 tons Ethylene glycol monomethyl ether per hour and square meter of catalyst bed cross-section) brought and added 9.3 parts of water per hour. At a pressure in front of the catalyst of 1.04 bar, a catalyst temperature of 575 ° C. is established. The reaction mixture is then cooled to 940C 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. As an absorption liquid 11.5 parts of water per hour at a temperature of 250C are via line (12) introduced into the cascade (4) and used. Within 720 hours, 10 152 parts of ethylene glycol monomethyl ether passed over the catalyst. You get via line (11) a total of 2,274 parts of unreacted ethylene glycol monomethyl ether and 5,860 parts of methoxyacetaldehyde. The conversion is 77.6 percent, the yield of methoxyacetaldehyde 76.4% of theory, based on converted ethylene glycol monomethyl ether.

Example 2 Analogously to Example 1, a mixture of 56.3 parts of 1,2-propylene glycol monomethyl ether is used and 14.1 parts of water with 58.5 parts of air within 5 hours at 600 ° C and 1.09 bar passed over a catalyst (0.79 parts) of the following composition: Particle Part of the grain size type of catalyst (weight) mm layer 1 Cu 2.5 0.2 to 0.75 (top) Layer 2 Ag 12 0.2 to 0.4 Layer 3 Ag 12.5 0.4 to 0.75 Layer 4 Ag 6 0.75 to 0.9 layer 5 Ag 6 0.9 to 1.0 layer 6 Ag 30 1 to 1.75 layer 7 Ag 31 1.75 to 2.5 (lowest) 0.34 part of unreacted propylene glycol monomethyl ether is obtained and 38.25 parts of methoxyacetone. The conversion is 99.4 percent, the yield Methoxyacetone $ 69.9 of theory, based on converted propylene glycol monomethyl ether.

Sign.

Claims (1)

Claim process for the production of aliphatic, with aliphatic Groups etherified hydroxycarbonyl compounds by catalytic oxidation of Hydroxy alcohols in the presence of detailed catalysts, characterized in that one aliphatic, etherified with aliphatic groups in the presence of hydroxy alcohols a catalyst with a total layer thickness of 5 to 100 millimeters and a) 3 or more layers of silver crystals, some of the layers being silver crystals 30 to 85 percent 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 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 particle size 0.2 to 0.75 mm, and one or more layers of copper crystals, which are 1 to 40 percent by weight of the catalyst with particles of grain size 0.2 to 0.75 mm, or o) 3 or more layers of silver crystals, some of the layers being silver crystals 30 to 85 percent 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 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 particle size 0.2 to 0.75 mm, and one or more layers of copper crystals, which are 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 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 on these elements, these layers Catalyst particles 0.5 to 10 percent by weight of the catalyst with particles of the Contains grain size 0.2 to 0.75 mm, oidized at a temperature of 450 to 700 ° C.