Manufacture and use of alkyl
The present invention relates to the manufacture of alkyl p-toluates from an alkyl p-toluic acid ester and a mono-functional, branched, linear or cyclic medium chain length alkyl alcohol, and their use as a plasticizer in polymers. Additionally, the present invention relates to articles and materials comprising such alkyl p-toluates.
1. A method for the manufacture of an alkyl p-toluate of formula I,
wherein R is a C 4 -C 20 branched, linear or cyclic alkyl radical, comprising:
oxidizing p-xylene to produce dimethyl terephthalate and a byproduct stream, wherein the byproduct stream comprises an ester comprising at least 80% by weight of C 1 -C 4 alkyl p-toluic acid ester; and
transesterifying the ester and one or more C 4 -C 20 mono-functional branched, linear or cyclic aliphatic alcohols at a reaction temperature of 160° C. to 260° C.,
wherein the transesterifying is in the presence of a catalyst.
2. The method according to claim 1 , wherein the ester is purified prior to the transesterifying.
3. The method according to claim 2 , wherein the amount of C 1 -C 4 alkyl p-toluic acid ester in said ester is at least 85 weight % based on the weight of said ester.
4. The method according to claim 1 , wherein the C 1 -C 4 alkyl p-toluic acid ester is methyl p-toluate.
5. A method for the manufacture of an alkyl p-toluate of formula I,
wherein R is a C 4 -C 20 branched, linear or cyclic alkyl radical, comprising:
a. oxidizing p-xylene to produce dimethyl terephthalate and a byproduct stream, wherein the byproduct stream comprises: an ester comprising a methyl p-toluate;
b. transesterifying the methyl p-toluate with one or more C 4 -C 20 mono-functional branched, linear or cyclic aliphatic alcohol in the presence of a catalyst at a reaction temperature of 160° C. to 260° C. to form a resultant product,
c. distilling the resultant product under vacuum to remove the unreacted methyl p-toluate and alcohol,
d. optionally raising the temperature,
e. optionally reducing the pressure, and
f. distilling off the alkyl p-toluate.
6. A method for the manufacture of an alkyl p-toluate of formula I,
wherein R is a C 4 -C 20 branched, linear or cyclic alkyl radical, comprising:
a. oxidizing p-xylene to produce dimethyl terephthalate and a byproduct stream, wherein the byproduct stream comprises: an ester comprising a methyl p-toluate;
b. transesterifying the methyl p-toluate with one or more C 4 -C 20 mono-functional branched, linear or cyclic aliphatic alcohol in the presence of a catalyst at a reaction temperature of 160° C. to 260° C. to form a resultant product,
c. distilling the resultant product under vacuum to remove the unreacted methyl p-toluate and alcohol to form a purified alkyl p-toluate,
d. filtering the purified alkyl p-toluate, and
e. optionally distilling the purified alkyl p-toluate under vacuum to distill off the alkyl p-toluate.
7. The method according to any one of claim 5 , or 6 , wherein the alkyl p-toluate has a color value of less than or equal to about 20 Pt—Co units.
8. The method according to claim 1 , wherein the manufactured alkyl p-toluate has an AHPA color number of less than 50 Pt—Co units.
9. The method according to claim 1 , wherein the transesterification is carried out without a solvent.
10. The method according to claim 1 , further comprising passing the transesterified material through a wiped-film evaporator.