DE1232573B - Process for the preparation of alkynols - Google Patents

Description

Process for the preparation of alkynols It is known that the alkynols under suitable conditions in liquid ammonia or other suitable solvents can be prepared by reacting stoichiometric amounts of ketones with acetylides. It is known that water, even in traces, has an adverse effect on this reaction (Herd and McPhee, J. Am. Chem. Soc., 69, 239, 1947).

There are also processes for the preparation of alkynols by condensation of acetylene with ketones in the presence of condensing agents known, in particular in the presence of alkali hydroxides and those in molar amounts, and in all cases are used in amounts that are not less than the amount of ketone.

None of the methods known for the preparation of alkynols is but completely satisfactory. It is especially desirable that not only high and the most quantitative possible yields, calculated on the starting ketone, can be achieved, but also that the use of large amounts of condensing agent is avoided. It is also desirable, as far as possible, to prevent the formation of unusable by-products, resulting from the condensation of the starting ketones, as well as the formation of acetylenic Avoid diols. In this regard, the use of alkali acetylides carried out reaction, although under absolutely anhydrous conditions and can be done with high yields, never entirely satisfactory. After all it is desirable to work under the greatest possible safety conditions in which the acetylene partial pressure in the gas phase is kept within modest limits, the is well below the explosive limit.

The inventive method for the preparation of alkynols by Reaction of acetylene with a ketone in liquid ammonia consists in that the reaction is carried out in the presence of no more than 10 percent by weight of water an approximately 500% alkali hydroxide solution at a molar ratio of alkali hydroxide to ketone from 1: 200 to 1:10 or 1:30, a pressure of 1 to 18 ata and temperatures from - 400 C to + 400 C.

The amount of water given above includes both added water as well as water of hydration which is present in one of the reactants used can be, and also the water formed during the reaction. Liquid ammonia is preferred as the ionizing, but not hydrolyzing, solvent, however aliphatic amines can also be used less advantageously.

Any aliphatic can be used as the ketone Ketone, aliphatic-aromatic or use aromatic ketone, provided it is soluble in the solvent used is.

To obtain methylbutynol, acetone is used as the ketone, however you can also use its aldol condensation product with the same effectiveness, i. H. so use the diacetone alcohol.

As already mentioned, the amount of acetylene must be in excess of that Ketone be present. A molar ratio of acetylene to ketone like 1.5: 1 is already useful, but preferably a ratio of at least 2: 1 is used and a ratio of 10: 1 is not exceeded for practical reasons.

When liquid ammonia is used, a molar ratio is acetylene to ammonia between 3: 7 and 3:30 advantageous.

The total pressure is higher than the pressure that is required to to keep the ammonia in the liquid state, since the acetylene partial pressure is taken into account is to be worn.

In order to work under safety conditions, the partial pressure is allowed of acetylene in the gas phase at the start of the reaction 60% to the vapor tension of the Do not exceed ammonia and acetylene based total pressures when in the above Temperature interval is being worked on. The total pressure preferably varies between 1 and 18 ata.

The amount of solvent is not critical and can be within very further limits fluctuate if only the above conditions are met will.

Any alkali metal hydroxide can be used as the catalyst however, sodium hydroxide and even more potassium hydroxide are preferred. the Use of potassium hydroxide further reduces the formation of by-products.

In the process of the invention, the yields are based on the ketone used, practically quantitative. The degrees of conversion are also already good in fairly short periods of time, and you can, for example, in approximately 3 hours to achieve a conversion up to 94ovo. However, the reaction time can be vary slightly in order to achieve different degrees of conversion from case to case.

In particular, such a high conversion can be achieved with continuous work be superfluous per throughput.

It is preferred to introduce the alkaline solution into the already the solution containing the ketone, achieving the instant dissolution of the catalyst is, but the ketone can also be added afterwards.

The temperature can be continuous or gradual in the course of the reaction increase.

It is surprisingly practical with catalytic amounts of alkali hydroxide to achieve quantitative yields, based on the ketone, and high degrees of conversion, although the work is carried out in the presence of appreciable amounts of water.

The method according to the invention can be carried out continuously, by, for example, in a system of the type indicated in the diagram of the drawing is being worked on. A reactor is filled with a solution by means of special metering pumps of acetylene is fed into ammonia from reservoir A, and alkali hydroxide is made in aqueous solution of 50 percent by weight from the reservoir K and ketone supplied to the storage container C in the desired proportions.

The acetylene consumed in the course of the reaction is removed from the gasometer G replaced.

The reaction mixture enters the vessel N from the reactor R, where the neutralization of the catalyst, for example with from the storage tank S removed ammonium chloride, takes place, and from there into an expansion chamber E, in which expelled the acetylene and ammonia and by means of a special compressor P are returned to the reactor R, while the remainder, containing the alkynol Crude product is sent to distillation, where it is removed from the impurities collected in W. is released. The following examples illustrate the invention.

Example 1.

In a stainless steel autoclave equipped with a paddle stirrer Steel of 700 cms capacity was dissolved 4.2 g of KOH, corresponding to 0.075 mol in 4.2 g of water. 131 g of anhydrous ammonia were added to this solution given, corresponding to 7.7 mol. Then 78 g of acetylene were in the ammonia, accordingly 3 moles, dissolved. Now was quickly at + 100 C by means of an injection pump anhydrous acetone in an amount of 93.5 g, corresponding to 1.44 mol, was added.

After 5 hours of reaction, ammonium chloride dissolved in ammonia, corresponding to 0.1 mol, added to stop the reaction. Then the autoclave cooled to 400 C, and the excess acetylene and ammonia were removed. The liquid residue taken up in water was neutralized with sulfuric acid and subjected to azeotropic distillation, and 1.38 moles of methylbutynol were obtained obtained, corresponding to 96%, based on the acetone introduced, and accordingly a yield, based on the catalyst, of 18.40 moles of methylbutynol per mole KOH. The water represents a total of (released by the potassium hydroxide in the course of the reaction Water and added water) an amount of 4.24 percent by weight, based on the ammonia. The total pressure was 12 ata and the acetylene partial pressure 57% of the total pressure.

Example 2 The procedure was essentially as in Example 1, with a molar ratio of catalyst to acetone = 1:30; Acetone to acetylene = 1: 2 and acetylene to ammonia = 3: 7, at a temperature of +100 C. To different Times were sampled. KOH in 50% aqueous solution was added; the results are shown in Table 1.

Table 1 Reaction time M 50% KOH solution obtained in minutes moles of methylbutynol ... O / a moles Acetone insert 30 54 60 65 90 72.2 120 76.5 180 83 240 86.2 300 1 89 420 1 91 The final yield, based on the catalyst, corresponds to 26.40 moles of methylbutynol per mole of catalyst.

The water content was 3.52%, based on the solvent, and is made up of the sum of what is added and what is released during the reaction Water together; the total pressure was 12.4 ata and the acetylene pressure (partial pressure) 58% of the total pressure.

EXAMPLE 3 The procedure is essentially as in Example 1, with molar ratios of acetone to acetylene = 2: 1, acetylene to ammonia = 3: 7. A number of batches were carried out at a temperature of +100 C, the results of which are shown in Table 2; a 500% aqueous KOH solution was used as the catalyst, and the molar ratios of catalyst to acetone = 1:14; 1:19; 1:30; 1:45; 1:60 used. Table 2 Moles of methylbutynol obtained ... 0/0 moles Reaction time acetone used in minutes KOH to acetone 1:14 z 9 1 1: 30 1 45 1: 60 30 68 62 52.6 144 1 44 60 79 73 65.1 54.25 | 53.26 90 85.4 81 72.25 61 59 120 89.2 86 76.5 65.5 63 180 93.7 92.5 83 71 68 240 95.8 95.4 86.2 75.9 72.3 300 92.2 96.0 89 79 75 420 - - 91.47 83.15 79 480! - 91.61 84.25 79.5 In the reactions carried out with a ratio of catalyst to acetone = 1:14 and 1:19, a precipitate consisting of alkaline methylbutynol occurred and the reaction continued in a heterogeneous phase.

The percentages of the total water present in the course of the experiments are listed below, depending on the ratios used between alkali hydroxide and ketone. Alkali hydroxide Total water present, to ketone based on the solvent Weight percent 1: 14 7.76 1: 19 4.35 1:30 3.52 1:45 2.43 1:60 1.75 In all tests the total pressure was 12.4 ata and the acetylene partial pressure was 58o of the total pressure.

Example 4 The procedure was essentially the same as in Example 1, with the following molar ratios: acetylene to acetone = 2: 1, Acetylene to ammonia = 3: 7.

The reaction was started at + 100 C and the temperature was raised gradually brought to + 400 C within 2 hours. It got a number of Approaches carried out, the catalyst used being KOH in 500% aqueous solution and different ratios of catalyst to acetone were used, and although 1: 50, 1: 60, 1: 120; samples were taken at different times.

The test conditions and the results are shown in Table 3.

Table 3 Moles of metholbutynol obtained Reaction time ° / o mol of acetone used temperature in minutes KOH to acetone = 1:50 (1:60 1 1: 120 OC 0 - I - +10 30 61.47 54.47 46.87 +25 60 77.8 73 63.2 +35 120 94 88.2 81 +40 180 97.7 93.67 87.5 +40 240 97.3 95.6 90.1 +40 360 97.3 95.15 92.8 +40 420 - - 94 +40 With a catalyst to acetone ratio of 1120, a yield (based on the catalyst) of 111 mol of methylbutynol per mol of catalyst was achieved.

The percentage amounts of the total water present in the course of the experiments are listed below, depending on the ratios used between alkali hydroxide and ketone. Alkali hydroxide Total water present, to ketone based on the solvent Weight percent 1: 50 2.2 1:60 1.75 1: 120 0.88 At the beginning of the experiment the total pressure was 12.2 ata, while the acetylene partial pressure was 58% of the total pressure; as a result of the introduction of acetone, the total pressure and the acetylene pressure reached values of 10.3 ata and 49-49% of the total pressure, respectively, which is due to the dissolution of the acetylene in the ketone. As the temperature rises and the dithynylation reaction proceeds, the total pressure rises gradually from 10.3 ata to 18 ata, while the acetylene partial pressure decreases to 140 / o of the total pressure at 400.degree.

Example S Working essentially as in Example 1, however instead of acetone, methyl t-butyl ketone was used, in the following molar ratios: KOH to ketone = 1:16, acetylene to ketone = 3: 1, acetylene to ammonia = 1: 4.

The temperature was +100 C. After a reaction time of 4 hours 98.1 0 / o 1-pentyne -3,4,4-trimethyl-3-ol, based on the ketone used.

In this experiment the total pressure was 12 ata, the acetylene partial pressure 45 ovo of total pressure; the total water present, based on the solvent, was 7%.

Example 6 The procedure was as in Example 5, but was used as Used ketone acetophenone.

90% of 1-butyn-3-phenyl-3-ol were obtained.

In this experiment the values for the total pressure were the acetylene partial pressure and the amount of water identical to those of Example 5.

Example 7 Example 1 was repeated, but diacetone alcohol was used instead of acetone used. The amount of moles of diacetone alcohol used was half that of the acetone moles. Under these conditions, 1.38 moles of methylbutynol were obtained, the one on the Corresponding catalyst-related yield of 18.40 moles of alkynol per mole of catalyst. This example clearly shows that the acetone can be replaced by diacetone alcohol can and that in this case only half of the moles necessary in the case of acetone Ketone is needed. In this example the values for the total pressure were den Acetylene partial pressure and the amount of water identical to those of Example 9.

Example 8 The procedure was essentially as in Example 1, with a molar ratio of anhydrous KOH to acetone = 1:10; Acetone to acetylene = 1:10 and acetylene to ammonia = 3: 9 at a temperature of -400C; were there after only 3 hours of reaction 90% methylbutynol, based on the acetone used, receive. In this experiment the total pressure was 2.3 ata, the acetylene partial pressure was 540/0 of the total pressure, the total water present based on the solvent, was 4.24%.

Example 9 The proportions used were: acetylene to ammonia = 1:10, acetone to acetylene = 1: 10, alkali hydroxide to acetone = 1 : 200.

The experiment was carried out at a temperature of 300 ° C. and a reaction time of 5 hours accomplished.

In this experiment, the total water present was 0.025 percent by weight, based on the solvent, the total pressure was 14 ata and the acetylene partial pressure 20% of the total pressure.

In this way, degrees of conversion, based on the acetone, of 98.45 ovo and yields, based on the catalyst, of 195.8 moles of methylbutynol achieved per mole of catalyst. It should be noted that in this attempt the Acetone-related conversion due to the large excess of acetylene over the ketone 98.45% reached.

Claims: 1. Process for the preparation of alkynols by Reaction of acetylene with a ketone in liquid ammonia, characterized in that that the reaction is carried out in the presence of no more than 10 percent by weight of water with an approximately 500% alkali hydroxide solution at a molar ratio of alkali hydroxide to ketone from 1: 200 to 1:10 or

1:30, a pressure of 1 to 18 ata and temperatures of - 400 C up to + 400 C.

Claims (1)

2. The method according to claim 1, characterized in that the Implementation at temperatures between +100 C and +300 C. 3. The method according to claim 1 and 2, characterized in that one the reaction temperature continuously or stepwise in the course of the reaction elevated. 4. The method according to claim 1 to 3, characterized in that one the reaction is carried out at an acetylene partial pressure which is at the start of the reaction Does not exceed 60 o / o of the total pressure produced by ammonia and acetylene. 5. The method according to claim 1 to 4, characterized in that one the reaction at a molar ratio of acetylene to solvent between 3 : 7 and 3:30. Documents considered: German Auslegeschrift No. 1,125,909; German Patent No. 885 846; Austrian patent no. 206887.