A method for synthesizing organic phosphine oxide compounds

Abstract

The invention discloses a method for synthesizing an organic phosphine oxide compound, and belongs to the field of organic synthesis. The method is realized by the following method: in an anhydrous and oxygen-free atmosphere, different types of alkanes or aromatic hydrocarbons are used as raw materials, and react with phosphorous acid under the catalysis of Lewis acid to generate the organic phosphine oxide compound. Compared with the prior art, the method has mild reaction conditions, simple operation, high yield, and simple and easily available raw materials, and is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis and relates to a method for synthesizing a class of organic phosphine compounds, in particular to a method for synthesizing organic phosphine oxide compounds. Technical Background

[0002] Organic phosphine oxide compounds are important chemical synthesis intermediates and are widely used in industrial production, such as the synthesis of various pesticides and chiral phosphine ligands. They can replace alkali metal cyanide as a coupling agent for the synthesis of heterocyclic compounds. At present, there are three main methods for the synthesis of organic phosphine oxide compounds: 1) using POCl3 as a raw material, after Friedel-Crafts alkylation reaction, using lithium aluminum hydride as a reducing agent to reduce the intermediate product to obtain an organic phosphine oxide compound; 2) using diethyl phosphite as a raw material, reacting with the corresponding Grignard reagent to generate the target product (Organometallics (2010), 29 (17), 3936-3950); 3) using PCl3 as a raw material, after Friedel-Crafts alkylation reaction, and then appropriately hydrolyzing to obtain the target product (Chemistry-A European Journal, 10.1002 / chem.202200507), but the purification of the intermediate Ph2PCl is relatively difficult, and the target product is only obtained with a yield of 37.0%. Moreover, the current industrial production methods generally have expensive production reagents, harsh production conditions, and require absolutely anhydrous and oxygen-free conditions, which to a certain extent limits the large-scale production of organic phosphine oxide compounds. Therefore, it is of certain practical significance to explore and improve the synthesis method of organic phosphine oxide compounds and develop a process route that is relatively simple to operate and low in cost. Summary of the invention

[0003] The purpose of the present invention is to provide a new method for synthesizing organic phosphine oxide compounds with high yield, mild reaction conditions and simple operation.

[0004] In order to achieve the above object, the reaction scheme of the present invention is as follows:

[0005] Under argon protection, adding tetrahydrofuran as a reaction solvent to a dry reactor, then adding an alkane or aromatic compound, stirring evenly, adding phosphorous acid, then adding a Lewis acid catalyst, heating to reflux, stopping the reaction after the reaction is completed, quenching, filtering, and drying to obtain an organic phosphine oxide compound;

[0006]

[0007] The alkane or aromatic compound is adamantane, cyclohexane or benzene; the Lewis acid is aluminum chloride, ferric chloride or boron trifluoride; the molar ratio of the alkane or aromatic compound, phosphorous acid and Lewis acid catalyst is 1:0.5-0.8:0.1-0.2.

[0008] The reaction time is 6-8h.

[0009] The beneficial effects of the present invention are: avoiding the use of highly dangerous lithium aluminum hydride and multi-step reactions, using cheap and readily available phosphorous acid and alkane or aromatic hydrocarbon reagents, directly synthesizing the target product in a one-step method, with a lower reaction temperature, milder reaction conditions, simpler operation, and a yield of more than 90%, which is very beneficial to actual industrial production. DETAILED DESCRIPTION

[0010] The following examples are helpful to further understand the present invention, but the content of the present invention is not limited thereto. Examples are as follows:

[0011] Embodiment 1:

[0012] Under argon protection, add 500 mL of tetrahydrofuran, a reaction solvent, to a dry reactor, then add 272 g of adamantane (compound 2a), 82 g of phosphorous acid, and 26.6 g of aluminum chloride in sequence, heat and reflux for 6 h, cool the reaction system to room temperature, extract, dry, and recrystallize to obtain 286 g of the target product, diadamantylphosphine oxide (compound 1a) (yield 90%). NMR data: 1 HNMR(CDCl3):1.74(br,12H),1.95-2.03(br,18H),5.61(d,J P-H =424Hz,1H). 31 P{H}NMR (162MHz, CDCl3): 59.2 (s, PH).

[0013] Embodiment 2:

[0014] Under argon protection, add 500 mL of tetrahydrofuran, a reaction solvent, to a dry reactor, then add 168 g of cyclohexane (compound 2b), 82 g of phosphorous acid, and 26.6 g of aluminum chloride in sequence, heat and reflux for 6 h, cool the reaction system to room temperature, extract, dry, and recrystallize to obtain 197 g of the target product dicyclohexylphosphine oxide (compound 1b) (yield 92%). NMR data: 1 H NMR(400MHz, CDCl3): δ6.29(dt,J H-P =433.8Hz,J H-H =2.8Hz,1H),2.03-1.20(m,22H). 31 P{ 1 H}NMR (162MHz,CDCl3):δ49.4.

[0015] Embodiment 3:

[0016] Under argon protection, add 500 mL of tetrahydrofuran, a reaction solvent, to a dry reactor, then add 156 g of benzene (compound 2c), 82 g of phosphorous acid, and 26.6 g of aluminum chloride in sequence, heat and reflux for 6 h, cool the reaction system to room temperature, extract, dry, and recrystallize to obtain 192 g of the target product diphenylphosphine oxide (compound 1c) (yield 95%). NMR data: 1 H NMR (CDCl3, 400MHz) δ7.44-7.64 (m, 6H), 7.65-7.80 (m, 6H), 8.08 (d, J = 480.6Hz, 1H); 13 C NMR (CDCl3, 75MHz) δ128.8 (d, J = 12.7Hz), 130.6 (d, J = 11.2Hz), 131.3 (d, J = 100.8Hz), 132.4 (d, J = 2.7Hz); 31 P NMR (162MHz, CDCl3) δ21.93ppm.

Claims

1. A method for synthesizing an organic phosphine oxide compound having the structural formula shown below, It is characterized in that This is achieved by the following method: Under argon protection, adding tetrahydrofuran as a reaction solvent to a dry reactor, then adding an alkane or aromatic compound, stirring evenly, adding phosphorous acid, then adding a Lewis acid catalyst, heating to reflux, stopping the reaction after the reaction is completed, quenching, filtering, and drying to obtain an organic phosphine oxide compound; The alkane or aromatic compound is adamantane, cyclohexane or benzene; and the Lewis acid is aluminum chloride.

2. The method for synthesizing the organic phosphine oxide compound according to claim 1, It is characterized in that The molar ratio of the alkane or aromatic compound, phosphorous acid and Lewis acid catalyst is 1: 0.5-0.8: 0.1-0.2.

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