Process for the manufacture of aliphatic phosphonic acids
AssigneeAmchem Products, Inc.
InventorsJohn E. Drach, Barry J. Pendell
Life of this patent
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Abstract
An improved process for the manufacture of an aliphatic phosphonic acid, particularly 2-chloroethylphosphonic acid, of the type wherein a diester of the aliphatic phosphonic acid, particularly bis-(2-chloroethyl)-2-chloroethylphosphonate, is reacted with anhydrous hydrogen halide, particularly hydrogen chloride, to produce a reaction product containing the aliphatic phosphonic acid, and the corresponding aliphatic halides particularly ethylene dichloride.
Claims35
In a process for the manufacture of an aliphatic phosphonic acid of the formula:
- ##STR7## of the type wherein a diester of the aliphatic phosphonic acid of the general formula:
- ##STR8## is reacted with anhydrous hydrogen halide selected from the group consisting of hydrogen chloride, hydrogen bromide, hydrogen iodide and hydrogen fluoride to produce a reaction product containing the corresponding aliphatic phosphonic acid and the corresponding aliphatic halides,
- wherein R.sub.1, R.sub.2 and R.sub.3 are each independently selected from the group consisting of substituted and unsubstituted aryl, alkyl, alkenyl, halo-substituted alkyl and halosubstituted alkenyl, having from 1 to 6 carbon atoms, wherein the improvement comprises
- a. reacting the diester and the anhydrous hydrogen halide at a first temperature of at least 100.degree. C, at a low pressure and for a first period of time to form a first reaction product;
- b. subsequently reacting the first reaction product and the anhydrous hydrogen halide at a second temperature of at least 100.degree. C, at a high pressure, said high pressure higher than said low pressure, and for a second period of time to form a second reaction product;
- and
- c. removing the aliphatic halides from at least one reaction product.
In a process for the manufacture of 2-chloroethylphosphonic acid of the type wherein bis(2-chloroethyl)-2-chloroethyl phosphonate is reacted with anhydrous hydrogen chloride to produce a reaction product containing 2-chloroethylphosphonic acid and ethylene dichloride, wherein the improvement comprises:
- a. reacting bis(2-chloroethyl)-2-chloroethyl phosphonate and anhydrous hydrogen chloride at a first temperature of at least 100.degree. C, at a low pressure of at least about 14 psia for a first period of time to form a first reaction product, said first period of time is until the first reaction product contains at least about 70% by weight of 2-chloroethylphosphonic acid;
- b. subsequently reacting the first reaction product and the anhydrous hydrogen chloride at a second temperature of at least 100.degree. C, at a high pressure of at least about 30 psia, said high pressure higher than said low pressure, and for a second period of time to form a second reaction product, said second period of time is until the second reaction product contains a required concentration of at least about 80% by weight of 2-chloroethylphosphonic acid;
- c. continuously removing ethylene dichloride from the first and second reaction product,
- wherein the steps of (a) reacting bis(2-chloroethyl)-2-chloroethylphosphonate and anhydrous hydrogen chloride, (b) reacting the first reaction product and anhydrous hydrogen chloride, and (c) removing ethylene dichloride are accomplished by:
- i. introducing continuously into the first and second reaction products an entrance stream comprised of anhydrous hydrogen chloride;
- and
- ii. removing continuously from the first and second reaction products an exit stream comprised of unreacted anhydrous hydrogen chloride and ethylene dichloride.
Dependencies are inferred from the claim text.