Patent ID: 7151190

Claim:
A process for preparing an aqueous solution of unsaturated quaternary ammonium salt of formula I in which R represents a methyl or benzyl radical, comprising reacting, in the presence of water, N,N-dimethyl-aminoethyl acrylate (DAMEA) with a quaternizing agent of formula II R—Cl (II) in which R is as defined above, wherein: (a) the reaction is carried out in a closed reactor, which comprises 5–60% of the amount by weight of the DAMEA necessary for the reaction and which has been pressurized by air or depleted of air to 0.5 to 3 bar, by continuously introducing, at a temperature of 35 to 65° C., the quaternizing agent of formula (II) and the water and finally the remaining DAMEA, until the desired concentration of the salt of the compound of formula (I) in the water is obtained, wherein the start of the introduction of the water beginning when 0–30% of the amount by weight of the quaternizing agent of formula (II) necessary for the reaction has been added; the start of the introduction of the remaining DAMEA begins when 20–80% of the amount by weight of the quaternizing agent of formula (II) necessary for the reaction has been added; and it being possible for the pressure at the end of the reaction to reach 9 bar; then (b) the reactor is depressurized while keeping the oxygen content constant by simultaneous introduction of air and, after returning to atmospheric pressure, the residual quaternizing agent is removed, and wherein no stabilizer is used in the process as a reagent and optionally a sequestering agent is used as a reagent.