DE1150051B - Process for reducing organic or inorganic chemical compounds - Google Patents

Description

Process for reducing organic or inorganic chemical Compounds In the known processes for the reduction of organic or inorganic chemical compounds are usually assumed to be hydrogen, which at higher pressure in the presence of catalytically active metals, especially nickel, is deposited. or more recently complex hydrides have been used. especially those of boron or aluminum, used, the reduction taking place under normal pressure can. In the first case, the application of higher pressure is a hindrance, while im second case the relatively difficult accessibility of the complex hydrides, for example of lithium alanate or lithium boranate, oppose industrial exploitation. Occasionally, considerable difficulties can also arise in the use of complex hydrides during the implementation of the action due to the presence of fixed starting and / or End products occur, such as in the case of sodium triethoxyaluminum hydride, of which large amounts must be used for reduction purposes, so that to its Solution considerable amounts of ether or tetrahydrofuran are required.

The use of lithium monocyano borohydride is of little use Opposite reducing power.

Recently, organoaluminum compounds have also been made. like aluminum trialkyls and aluminum dialkyl hydrides have been proposed as reducing agents.

Their use on a larger scale is difficult to handle the inflammable and moisture-sensitive compounds.

There has now been a new process for reducing organic or inorganic chemical compounds found which runs in a homogeneous liquid phase. no Difficulty caused by solids precipitation, avoids higher pressure and usually carried out without the use of an additional solvent or diluent will.

The process of the invention is through the reaction of silicon hydride compounds with the organic or inorganic chemical compound to be reduced in Presence of a boron halide, in particular a boron trichloride, characterized.

For example, phenylethylamine is included when boron trichloride is introduced into a mixture of diethylsilane and benzyl cyanide. Arise as intermediaries while organoboron nitrogen compounds, which are mostly new substances and be hydrolyzed. Preferred reducible organochemical compounds are In addition to the nitriles, the carboxylic acids, aldehydes, ketones, esters and acid amides. at The inorganic-chemical starting materials are, in particular, the halides. Nitrates, phosphates and similar compounds of the elements.

The reduction of an aldehyde to alcohol takes place according to the following equations: O 3 R3SiH + BCIs + 3 RC + H ç 3 R2SiCl + (R-CH2-O) 3B (1) (R # H2-O) B. Hydrolysis 3 R-CH2OH t B (OH) (2) The silicon hydrogen compound, which is often also used as a solvent or diluent, is converted into a silicon halogen compound during the reaction, which can be converted back into the silicon hydrogen compound with activated sodium hydride in accordance with the process of German Patent 1,055,511. This means that the silicon hydrogen compound actually serves as a hydrogen carrier.

Sometimes it is advantageous to add inert diluents to the reaction mixture to add. For this purpose, ethers and aliphatic as well as aromatic are particularly useful Hydrocarbons are suitable, which can also be substituted. Unsaturated Organic compounds combine with the boron halides to form boron alkyls around and therefore ruled out as usable diluents.

The reaction according to the invention takes place even at low temperatures very fast. The reduction is smooth even between 0 ° C and room temperature perform, but elevated temperatures are sometimes required for the reaction.

Depending on the expected reaction product, the one to be used Silicon hydrogen compound selected. One usually becomes a low-boiling silicon hydride compound use to post the separation of the silicon halogen compounds formed to facilitate the response.

The decomposition of the boric acid esters obtained as intermediates, Organoboron nitrogen and similar compounds are usually used in organic Chemistry known methods carried out.

If the boron halide is introduced in excess, intermediate compounds are formed obtained, which in addition to a B-O-C or B-N-C bond also contain B-C bonds, which can be used for various special purposes. So you have it in hand to direct the reaction in such a way that either as little as possible or as little as possible a lot of substances containing hydrogen boride are formed.

Example 1 In a mixture of 40 parts by weight of benzyl cyanide and 133 parts by weight of diethylsilane gradually became 51 parts by weight of boron trichloride initiated.

The reaction temperature was initially 40 to 500 C and was against Increased to 900 C at the end. After the reaction, the resulting diethylchlorosilane-diethyldichlorosilane mixture became distilled off and converted again into diethylsilane by means of activated sodium hydride.

The residue from vacuum distillation provided a colorless organoboron nitrogen compound to which a little ether was added, whereupon with the addition of dilute it Hydrochloric acid was hydrolyzed. There was a slight elimination of hydrogen established.

After concentrating and adding potassium hydroxide solution, it was shaken out in the ether, then the ether evaporated and the residue distilled in vacuo.

32.5 parts by weight of pure phenylethylamine were obtained with a Bp. 10 mm Hg = 78 to 800 C.

Example 2 6 parts by weight were added to 28 parts by weight of triethylsilane Titanium tetrachloride was added dropwise, then the temperature increased to 60 to 1000 C. and 4.8 parts by weight of boron trichloride initiated. The reaction mixture turned colored initially light brown, then dark.

After the volatile components had been distilled off in vacuo, 2.9 remained Parts by weight of a black powder, consisting of a mixture of titanium with lower titanium hydrides and titanium chlorides.

Example 3 In a solution of 20.4 parts by weight of methyl stearate 10.5 parts by weight of boron trichloride were introduced into 32 parts by weight of triethylsilane.

An exothermic reaction set in, the conversion at 60 was continued until 700 C. When the reaction was complete, the resulting Triethylchlorosilane and the excess triethylsilane, together 39 parts by weight, distilled off in vacuo. The stearyl borate present as a solid white distillation residue was saponified at 800 C with aqueous hydrochloric acid and the mixture then heated to 03 C cooled down. 18.3 parts by weight of octadecalone were obtained, corresponding to one Yield of 990/0 of theory. Based on the melting point and IR images it was found that it was pure alcohol.

Example 4 A suspension of 21.9 parts by weight of lauryl chloride in 34.8 parts by weight of triethylsilane was mixed with 11.7 parts by weight of boron trichloride brought to reaction at 600 C. After the reaction and subsequent separation of the resulting triethylchlorosilane and the hydrolysis according to Example 3 was the reduced main product extracted twice with ether, dried and im Vacuum distilled. At a boiling point of 113 to 1160 C below 1 to 2 mm Hg Pressure, 18.2 parts by weight of lauryl alcohol were obtained, corresponding to a yield 98 per cent of theory. Based on the IR recordings, it was the pure one Alcohol.

Example 5 The following organic compounds were obtained after the in the previous examples reduced scheme: Heptaldehyde to heptanol Cyclohexanone to cyclohexanol methyl nonyl ketone to methyl nonyl carbinol lauric acid to lauryl alcohol (organic acids are initially evidenced by boron trichloride converted into the acid chlorides, which are then reduced.) Lauryl acid amide to laurylamine benzophenone to benzhydrol benzoic acid benzyl ester to benzyl alcohol All reactions could, if desired, after the separation of the obtained Chlorosilane and, before hydrolysis, the organoboron compounds formed, containing BOC or BNC groups. They mostly make oils or viscous colorless crystalline substances.

Claims (2)

PATENT CLAIMS: 1. Process for the reduction of organic or inorganic chemical compounds, characterized in that a silicon hydrogen compound with an organic or inorganic chemical compound in the presence of a Boron halide, in particular a boron chloride, at a temperature between 0 and 1200 C is implemented. 2. The method according to claim 1, characterized in that the implementation is carried out in an inert solvent or diluent. Considered publications: Annalen der Chemie, Vol. 623 (1959), pp. 14 to 16; Brd, 607 (1957), pp. 34 to 35; Journal of Practical Chemistry, Vol. 6 (1958), p. 80.