Claims
- 1. A process for the preparation of a phosphine of the formula
- R--PH.sub.2
- in which R is a straight chain or branched alkyl group having from 1to 24 carbon atoms comprising reacting phosphine (PH.sub.3) with a reagent of the formula R-hal wherein R has the meaning mentioned and halo is chlorine or bromine, wherein a catalyst selected from the group consisting of tetraalkylammonium and tetraallkylphosphonium salt is added to the reactants, and the reaction is conducted in the presence of an alkali metal hydroxide solution at temperature between -20 and 200.degree. C. and a pressure of 1 to 10 bar, in which process for each mole of hal at least 1 mole of alkali metal hydroxide is used.
- 2. A process for the preparation of a phosphine of the formula ##STR4## in which m stands for an integer from 2 to 4, and A and B is a straight chain or branched alkyl group having from 1 to 24 carbon atoms, a cycloalkyl, benzyl or allyl group, hydrogen or phenyl group comprising reacting phosphine (PH.sub.3) with a reagent of the formula ##STR5## wherein A, B and m have the meaning mentioned and hal is chlorine or bromine, wherein a catalyst selected from the group consisting of tetraalkylammonium and tetraalkylphosphonium salt is added to the reactants and the reaction is conducted in the presence of an aqueous alkali metal hydroxide solution at temperature between -20 and 200.degree. C. and a pressure of 1 to 10 bar, in which process for each mole of hal at least 1 mole of alkali metal hydroxide is used.
- 3. The process as claimed in claim 1, wherein the reaction is carried out in the presence of an organic solvent selected from the group consisting of aliphatic and aromatic hydrocarbons having 5 to 16 carbon atoms.
- 4. The process as claimed in claim 1, wherein the reaction is carried out at temperatures between 0 and 50.degree. C.
- 5. The process as claimed in claim 1, wherein the catalyst is used in concentration of 0.1 to 5 mole %, based on the phosphine used.
- 6. The process as claimed in claim 1, wherein the alkali metal hydroxide solution is selected from the group of aqueous NaOH and KOH having a concentration of 50 to 70% by weight.
- 7. The process as claimed in claim 2, wherein the reaction is carried out in the presence of an organic solvent selected from the group consisting of aliphatic and aromatic hydrocarbons having 5 to 16 carbon atoms.
- 8. The process as claimed in claim 2, wherein the reaction is carried out at temperatures between 0 and 50.degree. C.
- 9. The process as claimed in claim 2, wherein the catalyst is used in a concentration of 0.01 to 5 mole %, based on the phosphine used.
- 10. The process as claimed in claim 2, wherein the alkali metal hydroxide solution is selected from the group consisting of aqueous NaOH and KOH having a concentration of 50 to 70% by weight.
Priority Claims (1)
| Number |
Date |
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Kind |
| 3731424 |
Sep 1987 |
DEX |
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Parent Case Info
This application is a continuation of application Ser. No. 240,099, filed 9/2/88 now abandoned.
The present invention relates to a process for the preparation of phosphanes of the general formulae ##STR1## in which R represents a straight-chain or branched alkyl group having 1 to 24 carbon atoms or a cycloalkyl, benzyl or allyl group, n is 1 or 2, m corresponds to 2, 3 or 4 and A and B are identical or different and have either the meaning or R, hydrogen or a phenyl group.
This process consists in the reaction of phosphane in the presence of a catalyst with reagents of the general formula Rhal or hal(C(A)(B)).sub.m hal, in which R, A, B and m have the meaning mentioned and hal stands for chlorine or bromine.
Organophosphorus compounds are becoming increasingly important in industry as herbicides, ligands in catalysts for hydroformylation (oxo synthesis), phase transfer catalysts (as phosphonium salts) and extractants (as tertiary phosphane oxides and phosphinic acids). Phosphane which can be easily prepared by means of known processes in industrial quantities is used as the building block for the synthesis of these classes of compounds.
By the prior art, trialkylphosphanes are available without difficulty by radical-initiated addition of PH.sub.3 to olefinic double bonds.
The controlled preparation of primary and secondary alkylphosphanes is considerably more difficult. Therefore, there has been no shortage of proposals to obtain these phosphanes; in particular, the reaction of PH.sub.3 with alkylhalides over noble metal catalysts or activated carbon has already been attempted (DE 2,407,461 A1). All prior art methods have disadvantages such as, for example, poor yields or undesired side products, which prevented their application in industry.
Surprisingly, it has now been found that the disadvantages of the known processes can be avoided, if a tetraalkylammonium or tetraalkylphosphoium salt is used as the catalyst in the reaction of phosphane with alkyl halides and the reaction is carried out in the presence of an aqueous alkali metal hydroxide solutions at temperatures between -20.degree. C. and 200.degree. C. and at a pressure of 0 to 10 bar, in which process for each mole of hal at least one mole of alkali metal hydroxide is used.
Advantageous reinforcement of the process according to the invention are: working in the presence of inert organic solvents; carrying out the reaction at temperatures between 0 and 50.degree. C.; using the catalyst in concentrations from 0.1 to 5 mole %, based on the PH.sub.3 used; using aliphatic or aromatic hydrocarbons having 5-16 carbon atoms, individually or as a mixture, as the inert organic solvent and using aqueous NaOH or KOH solution having a concentration of 50-70% by weight as the alkali metal hydroxide solution. In this reaction, the phosphane is deprotonated with concentrated aqueous alkali metal hydroxide solution. This process is critically dependent on the use of the catalyst in the form of an ammonium or phosphonium salt. Without such a catalyst, there is virtually no reaction. In some cases, it is advantageous to dispense completely with the use of an inert organic solvent. In the reaction of PH.sub.3 with methyl chloride, for example, the reaction products methylphosphase and possibly dimethylphosphane can be recovered directly on completion of the reaction by releasing the autoclave and subsequent gentle heating. The isolation of the products in the form of their hydrogen phosphonium salts is achieved in the known manner by passing the reaction gas through wash bottles containing dilute HCl (asbsorbs only methylphosphane) and/or concentrated HCl (absorbs (CH.sub.3).sub.2 PH, CH.sub.3 PH.sub.2 and (CH.sub.3).sub.3 P). At the same time, excess methyl chloride and PH.sub.3 may still be present in the gas. By adding an appropriate amount of alkali metal hydroxide, the phosphanes can be liberated again in a controlled fashion. The process according to the invention is particularly suitable for the monoalkylation of PH.sub.3. The specificity and simplicity of the process are not achieved by any other known process. Furthermore, only relatively low-priced reagents are used. However, the preparation of dialkylated products is also possible, although in this preparation the removal and recycling of monoalkylated product is recommended. Thus, for example (CH.sub.3).sub.2 PH can be obtained, a compound whose structural simplicity is in stark contrast to the difficulty of its past preparation.
Especially in these cases where alkyl halides which are gaseous under standard conditions (methyl chloride, ethyl chloride), are used, it is advantageous to carry out the reaction in an autoclave under pressure (Examples 1-3, method A). In principle, all reactions can be carried out by method A (see Example 4).
According to method B, the reaction is carried out under atmospheric pressure or at so small a pressure (250 mbar) that the reactions can be carried out in standard glass apparatuses.
General operating conditions for method A (amounts specified in Table 1).
US Referenced Citations (1)
| Number |
Name |
Date |
Kind |
|
4073810 |
Hestermann et al. |
Feb 1978 |
|
Foreign Referenced Citations (4)
| Number |
Date |
Country |
| 2727390 |
Jan 1979 |
DEX |
| 11934 |
Jul 1967 |
JPX |
| 1016291 |
May 1983 |
SUX |
| 928207 |
Jun 1963 |
GBX |
Non-Patent Literature Citations (2)
| Entry |
| Houben-Weyl, "Methoden zur Herstellung und Umwandlung von Phosphinen . . .", Methoden der Organischen Chemie, vol. XII/1, 1963, p. 17. |
| Jolly, William L. et al., Inorganic Synthesis 11, 124 (1968). |
Continuations (1)
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Number |
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| Parent |
240099 |
Sep 1988 |
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Patent Grant
5003108
