Abstract: An alkyl (meth)acrylate is prepared by a direct esterification (in 1) of (meth)acrylic acid by the corresponding alcohol, catalysed by H.sub.2 SO.sub.4. To the crude reaction mixture (C.sub.1) comprising the desired ester, alcohol, (meth)acrylic acid, alkyl hydrogen sulphate and traces of H.sub.2 SO.sub.4, there is added (in 3) a base to neutralize the acidic species, the resulting salts passing into the aqueous phase (A.sub.1), which is separated from the organic phase (O.sub.1) containing the desired ester. The light products (L.sub.1) containing the alcohol are recovered (in 4) from the aqueous phase, and the waste waters (W.sub.2) are expelled. A hydrolysis is carried out (in 8) of the alkyl hydrogen sulphate present in the aqueous phase (A.sub.1) obtained after the separation which is carried out after neutralization (in 3), to form the alcohol and H.sub.2 SO.sub.4 in this phase, the acidic species resulting from the hydrolysis are neutralized by introduction of a base .

Abstract: A compound (I) is prepared by reacting at least one (meth)acrylate (II) with a heterocyclic alcohol (III), in the presence of at least one catalyst chosen from magnesium alkoxides Mg(OR).sub.2. ##STR1## R=C.sub.1 -C.sub.4 alkyl. R.sup.1 =H, CH.sub.3 ; A, B=straight or branched C.sub.2 -C.sub.5 hydrocarbon chain; R.sup.2 =C.sub.1 -C.sub.4 alkyl.

Abstract: Process for the continuous preparation of lower acrylates from an aqueous solution of acrylic acid and from a lower alcohol, the esterification reaction taking place in liquid phase in a reactor, at a temperature of between 50.degree. C. and 110.degree. C., in the presence of at least one esterification catalyst, the reaction products leaving the reactor, consisting of a mixture of lower acrylate, water and unreacted starting compounds, being sent to the bottom of a distillation column and the lower acrylate being recovered at the head of the said column and sent towards a purification device. The said aqueous solution of acrylic acid is introduced at the bottom of the said distillation column where it is subjected to an azeotropic distillation, the stream obtained at the foot of the column, enriched in acrylic acid, then being recycled towards the reactor so that at the entry of the said reactor the molar ratio of acrylic acid to the lower alcohol is between 0.5 and 4.5.

Abstract: Process for the purifiying water using an effective proportion of a flocculating agent consisting of a reverse microlatex comprising a polymer of at least one water-soluble cationic vinyl monomer, which may be copolymerized with at least one water-soluble anionic or non-ionic vinyl monomer, possessing a molecular weight at least equal to 2.times.10.sup.6.The said microlatex is in the form of particles of a microlatex having a diameter of between 30 and 160 nm and its polydispersity index is between 1.05 and 1.2.