Process for preparing tertiary alkyl esters of (meth)acrylic acid having at least 4 carbon atoms in the alkyl radical

A process for preparing tertiary alkyl esters of (meth)acrylic acid having at least 4 carbon atoms in the alkyl radical, comprising:

• (1) reacting (meth)acrylic acid with at least one olefin of formula I:
• in which R1 and R2 may be the same or different and are each an alkyl radical, and R3 is a hydrogen atom, an alkyl radical, a cycloalkyl radical, an aryl radical, an alkylcycloalkyl radical which is bonded to the olefinically unsaturated carbon atom via an aliphatic or cycloaliphatic carbon atom, an alkylaryl radical which is bonded to the olefinically unsaturated carbon atom via an aliphatic or aromatic carbon atom, a cycloalkylaryl radical which is bonded to the olefinically unsaturated carbon atom via a cycloaliphatic or aromatic carbon atom, or an alkylcycloalkylaryl radical which is bonded to the olefinically unsaturated carbon atom via an aliphatic, cycloaliphatic or aromatic carbon atom;
• in homogeneous phase in the presence of an acidic catalyst in a reactor to form a first mixture,
• (2) discharging said first mixture from the reactor to obtain a discharged reaction mixture,
• (3) separating the discharged reaction mixture into a catalyst mixture which comprises the catalyst and a tertiary alkyl ester mixture which comprises the tertiary alkyl ester of (meth)acrylic acid having at least 4 carbon atoms in the alkyl radical, and
• (4) removing the tertiary alkyl ester of (meth)acrylic acid having at least 4 carbon atoms in the alkyl radical from the tertiary alkyl ester mixture,
• which comprises,
• (5) in (4), adding in an amount of from 400 to 700 ppm, by weight, at least one compound S which comprises at least one N-oxyl group, as stabilizer.