Synthesis method of alkyl phosphinic acid and aluminium salt thereof under normal-pressure mild condition

Abstract

The invention discloses a synthesis method of alkyl phosphinic acid and aluminium salt thereof under a normal-pressure mild condition. A hypophosphorous acid solution and alcohol are adopted as raw materials, by means of an organic solvent which has an azeotropy point with water, through in-situ reaction of olefin, the alkyl phosphinic acid is synthesized, after reaction is completed, the pH is adjusted, an aluminium salt solution is added, and alkyl aluminum hypophosphite precipitates as a white precipitate. According to the synthesis method of the alkyl phosphinic acid and the aluminium saltthereof under the normal-pressure mild condition, operation is simple and convenient, concentration of the hypophosphorous acid solution is avoided, energy consumption is reduced, and the efficiencyis improved; the alcohol not only can be used as the raw material for in-situ reaction of the olefin, but also can promote homogeneous system generation of the reaction, so that inconvenience of easyauto-agglutination brought by using acetic acid as a solvent and using olefin as an oligomer is eliminated; by using the solvent co-boiling with water, the purposes of solvent recovery and recycle areachieved, and it is easier to obtain the high-quality salt-forming product; the method is implemented under the normal-pressure mild condition, a security coefficient is high, the reaction risk is small, a synthesis technology is more energy-saving, environmentally friendly and efficient, and industrial production is easier to achieve.

Description

technical field [0001] The invention relates to a method for synthesizing alkylphosphinic acid and its aluminum salt under normal pressure and mild conditions, and belongs to the field of synthesizing halogen-free flame retardants. Background technique [0002] As a newly developed phosphorus flame retardant, dialkyl phosphinate has been widely used in the electrical and electronic industry due to its environmental protection and high efficiency. For the development of such flame retardants, the key lies in the synthesis of alkyl phosphinic acid intermediates. At present, the synthesis methods of alkylphosphinic acid mainly include aluminum trichloride catalyzed method, Grignard reagent conversion method and free radical addition method, but the first two technological conditions are difficult to realize industrialization. CN102050835A reports the synthesis of alkylphosphinic acid through the conversion of Grignard reagents. However, due to the strong sensitivity of Grigna...

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Problems solved by technology

However, due to the strong sensitivity of Grignard reagents to water, this process is difficult to realize industrialization

CN102718798B has reported to obtain two (alpha-hydroxyl) alkyl phosphinic acid by reaction of hypophosphorous acid and aldehyde, then utilize dehydroxylation to obtain the method for alkyl phosphinic acid, but need to use acidic hydrogen iodide extremely strong in its reduction process acid, the price is very expensive, and industrial production is also limited

CN103073577B has reported the synthetic method of dialkylphosphinic acid when taking toluene as solvent, this method needs pressurized condition and high-concentration hypophosphorous acid to be raw material, and high-concentration hypophosphorous acid then needs to be obtained by concentrating 50% hypophosphorous acid aqueous solution, by hypophosphorous acid The effect of low decomposition temperature, the realization of the concentration step is very limited

[0004] In the technology report of the synthetic alkylphosphinic acid of relevant free radical addition method, the main problem that exists has: (1) technology is loaded down with trivial details, because phosphoric acid raw material more utilizes the pre-acidification of sodium hypophosphite or the concentrated realization of hypophosphite aqueous solution, Increased process steps; (2) The use of raw materials is easily limited, and the introduction of alkyl substituents often selects olefins as reaction substrates. As the initial product of cracking in the petrochemical industry, olefins have low boiling points, easy self-polymerization, and difficult Disadvantages of storage, very limited in industrialization

(3) Most of the solvents are a mixture of acetic acid and water, which increases the difficulty of product separation and solvent reuse, and brings greater pressure on environmental protection

(4) Most of the processes choose high-pressure reaction, the reaction risk coefficient increases, and there are higher requirements for the material of the reaction device, which increases the cost of safe production

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