Synthesis Of Bis(1-alkoxy-2,2,6,6-tetra Methylpiperidine-4-yl) Sebacate

N-alkoxy hindered amines（NORs）are a kind of multifunctional light stabilizers with high efficiency,acid resistance and flame retardancy.However,there are few industrialized varieties at present.Moreover,their chemical structure and synthesis process are very complex.So,the development of NORs with better performance,simple structure and synthesis process should become an important research topic.Bis（1-alkoxy-2,2,6,6-tetramethylpiperidine-4-yl）sebacate is a type of NORs with simple chemical structure and synthesis process.The long chain in the structure makes it have good thermal stability and good dispersion in the material.The moderate molecular weight makes it have a certain migration resistance,but its synthetic process is not mature.So it is of great significance to carry out the research on its synthesis process.1-Propoxy-2,2,6,6-tetramethylpiperidine-4-ol and 1-isopropoxy-2,2,6,6-tetramet-hylpiperidin-4-ol were synthesized through O-alkylation reaction by using4-hydroxy-2,2,6,6-tetramethylpiperidinenitroxyradicalasrawmaterials,n-butyraldehyde and isobutyraldehyde respectively as alkylation reagent,CuCl as catalyst,and 30%H₂O₂ as oxidant and toluene as solvent.The experimental results revealed that the optimal conditions of 1-propoxy-2,2,6,6-tetramethylpiperidine-4-ol were as follows:n（ZJ-701）:n（n-butyraldehyde）:n（H₂O₂）:n（CuCl）=1:3.56:2.80:0.045,O-alkylation reaction temperature being 20℃,O-alkylation reaction time being12 h.The better purification mathod of crude product was recrystallization with the mixed solvent of acetone and water with m（acetone）:m（water）=0.75:1.Under the above conditions,the weight fraction reaches 98.25%,the separated yield was52.33%and the melting point was 60⁶2℃.The optimal conditions of1-isopropoxy-2,2,6,6-tetramethylpiperidine-4-ol were as follows:n（ZJ-701）:n（isobutyraldehyde）:n（H₂O₂）:n（CuCl）=1:4.64:2.12:0.045,the reaction temperature being 20℃,the reaction time being 12 h.The better purification mathod of crude product was recrystallization with the mixed solvent of acetone and water with m（acetone）:m（water）=0.75:1.Under the above conditions,the weight fraction of the product was 99.37%,the separated yield was 53.21%and the melting point was99¹00℃.Five bis（1-alkoxy-2,2,6,6-tetramethylpiperidine-4-yl）sebacate were synthesized through transesterification by using 1-alkoxy-2,2,6,6-tetramethylpiperidine-4-ol and dimethyl sebacate as raw materials,LiOH as catalyst,tetrabutylammonium bromide as phase transfer catalyst,n-heptane as solvent,and separating methanol by water splitter in transesterification process.The optimal conditions was n（LiOH）:n（TBAB）:n（1-alkoxy-2,2,6,6-tetramethylpiperidine-4-ol）:n（dimethylsebacate）=1.82:0.062:2.2:1.The better purification mathod of crude product was washing with the mixed solvent with m（methanol）:m（water）=1:1.Under these conditions,the weight fraction of bis（1-methoxy-2,2,6,6-tetramethylpiperidine-4-yl）sebacate,bis（1-ethoxy-2,2,6,6-tetramethylpiperidine-4-yl）sebacate,bis（1-propoxy-2,2,6,6-tetramethylpiperidin e-4-yl）sebacate,bis（1-isopropoxy-2,2,6,6-tetramethylpiperidine-4-yl）sebacate and bis（1-cyclohexoxy-2,2,6,6-tetramethylpiperidine-4-yl）sebacae were respectively 92.62%,95.82%,95.88%,97.24%and 99.11%,and the yield were respectively 79.31%,81.30%,84.29%,83.08%and 85.15%.