Method for prevention of premature polymerization

1. A method to prevent a premature polymerization of a polymerizable compound with at least one conjugated unsaturated group comprising the steps of:

(a) providing the polymerizable compound, or providing a reaction mixture with starting components required for the formation of the polymerizable compound,

(b) adding a salt of at least one of a phenoxazine, phenodiazine, or phenothiazine dye-based compound to said polymerizable compound, and

(c) adding a sulfonate salt to said polymerizable compound to obtain a mixture,

wherein said polymerizable compound is selected from the group consisting of acrylic acid, methacrylic acid and esters thereof, and

wherein said sulfonate salt has the general formula A + RSO 3 − ,

wherein R is selected from the group consisting of an aliphatic moiety having from 1 to 30 carbon atoms, an aliphatic moiety having from 1 to 30 carbon atoms being substituted by cycloalkyl, aryl, aralkyl, fluoroalkyl, fluoroaryl, fluoroaralkyl, chloroalkyl, chloroaryl, or chloroaralkyl having from 6 to about 12 carbon atoms, heterocyclyl, any aliphatic moiety, alkyl or alkylene fluoroalkyl, fluoroalkylene, chloroalkyl, or chloroalkylene chain being optionally interrupted by one or more hetero atoms, or R is selected from the group of organic groups comprising a hydroxyl substituted aromatic group.

2. The method according to claim 1 , wherein said salt of an azine dye-based compound has the formula (ADZ):

wherein:

Y is selected from the group consisting of S, O, or NR 11 , wherein

R 11 is selected from the group consisting of hydrogen, an aliphatic moiety having from 1 to 20 carbon atoms, cycloalkyl, aryl, aralkyl, fluoroalkyl, fluoroaryl, fluoroaralkyl, chloroalkyl, chloroaryl, or chloroaralkyl having from 6 to 12 carbon atoms;

R 1 -R 4 may be the same or different and each is selected from the group consisting of hydrogen, an aliphatic moiety having from 1 to 20 carbon atoms, cycloalkyl, aryl, aralkyl, fluoroalkyl, fluoroaryl, fluoroaralkyl chloroalkyl, chloroaryl, or chloroaralkyl having from 6 to 12 carbon atoms, heterocyclyl, any alkyl, alkylene, fluoroalkyl, fluoroalkylene chloroalkyl, or chloroalkylene chain being optionally interrupted by one or more hetero atoms;

R 1 and R 2 together, or R 3 and R 4 together, may form part of an alicyclic or heterocyclic moiety having from 4 to 10 ring members;

R 5 -R 10 may be the same or different and each is selected from the group consisting of hydrogen, an aliphatic moiety having from 1 to 20 carbon atoms, cycloalkyl, aryl, aralkyl, fluoroalkyl, fluoroaryl, fluoroaralkyl, chloroalkyl, chloroaryl, or chloroaralkyl having from 6 to 12 carbon atoms, heterocyclyl, any alkyl or alkylene fluoroalkyl, fluoroalkylene, chloroalkyl, or chloroalkylene chain being optionally interrupted by one or more hetero atoms;

R 5 and R 7 together, or R 6 and R 8 together, or R 1 and R 7 together, or R 2 and R 9 together, or R 3 and R 8 together, or R 10 and R 4 together, may form part of an alicyclic or heterocyclic moiety having from 4 to 10 ring members; and

Z − is any anion selected from the group consisting of Cl − , Br − , I − and F − .

3. The method according to claim 1 , further comprising the step of heating said mixture to a temperature of 100 to 300° C. under a reduced pressure of from 0.001 to 1 mbar.

4. The method according to claim 3 , further comprising the step of adding a second inhibitor prior the heating step.

5. The method according to claim 4 , wherein said second inhibitor is selected from the group consisting of hydroquinone, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol and 4-heptoxyphenol.

6. The method according to claim 1 , further comprising the step of distilling said polymerizable compound.

7. The method according to claim 1 , wherein the reaction mixture comprises an acrylic or methacrylic acid ester and an alcohol and the polymerizable compound is formed by a transesterification reaction.

8. A method of increasing the inhibitory activity of an inhibitor as referred to in claim 1 , comprising the step of dissolving the inhibitor in a mixture of the polymerizable compound and an alcohol, followed by removal of the alcohol.

9. The method according to claim 8 , wherein the alcohol is methanol.

10. The method according to claim 1 , wherein the polymerizable compound is an ester of acrylic or methacrylic acid with a fatty alcohol, with from 8 to 20 carbon atoms.