Synthesis Of Tris(1-methoxy-2,2,6,6-Tetramethylpiperidin-4-yl)Phosphite

N-Alkoxyl hindered amine(NORs)is a type of light stabilizers with non-toxic,non-halogen,low smoke and excellent light stabilization,may also be used as flame retardants or flame retardant synergists with significant flame retardancy and flame retardant synergism at very low levels.Therefore,it was considered as a great development potential green and high efficient flame retardants.However,the flame retarded effect of the current varieties is only obvious in the polypropylene thin products,in addition,their chemical structures are extremely complex,so the synthesis processes are very conplicated,the discharge of three wastes are very large,and the products are expensive.Therefore,it is of great theoretical and practical significance to develop some NORs with better flame retardant effect,wider application range,simple structure and preparation process,less waste discharge and cheaper price.In the paper,the synthesis processes and purification schemes of 1-methoxy-2,2,6,6-tetramethylpiperidin-4-ol,1-alkoxy-2,2,6,6-tetramethylpiperidin-4-ol and tris(1-methoxy-2,2,6,6-tetramethy]piperidin-4-yl)phosphite were studied,and their structures were characterized by IR,1H-NMR.,13C-NMR and 31P-NMR.1-methoxy-2,2,6;6-tetramethylpiperidin-4-o1 was synthesized through a free radical reaction by using acetone and 4-hydroxy-2,2,6;6-tetramethyl-1-piperidinyloxy(ZJ-701)as raw materials,30%hydrogen peroxide as oxidant,CuCl as catalyst.The results revealed that the optimal conditions were as follows:the reaction time being 24 h,and the reaction temperature being 30℃,n(ZJ-701):n(acetone):n(H2O2):n(CuCl)=1:14.96:2.73:0.076.The crude products was recrystallized with a mixed solvent of methanol/water.The preferred recrystallization conditions were as follows:v(methanol):v(deionized water)=1:1,w(crude):w(mixed solvent)=1:4.Under the above conditions,the separated yield of the products was 46.5%,the mass fraction was more than 99%,and the melting point was 88-91 ℃.1-methoxy-2,2;6,6-tetramethylpiperidin-4-ol was synthesized through a free radical reaction by using ethanol and ZJ-701 as raw materials,30%hydrogen peroxide as oxidant,the complex from copper chloride and pyridine as catalyst.The results revealed that the optimal conditions were as follows:the reaction time being 12 h,and the reaction temperature being 78 ℃,n(ZJ-701):n(alcohols):n(H2O2):n(CuCl2):n(pyridine)=1:39.25:17.01:0.034:0.35.Under the above conditions,the yield of 1-methoxy-2,2,6,6-tetramethylpiperidim-4-ol was 60.6%,the mass fraction was 98.8%;the separated yield of the products was 44.6%,the mass fraction was more than 99%,and the melting point was 88-91 ℃.Based on the above conditions,a series of 1-alkoxy-2,2,6,6-tetramethylpiperidin-4-ol was successfully synthesized by replacing ethanol with other alcohols.The results are as follows:The yield of 1-ethoxy-2,2,6,6-tetramethylpiperidin-4-ol was 52.2%,the mass fraction was 82.9%,the separated of mass fraction was 98.9%,and the melting point was 84-86 0C;The yield of 1-propoxy-2,2,6,6-tetramethylpiperidin-4-ol was 77.2%,the mass fraction was 81.8%,and the separated of mass fraction was 96.6%;The yield of 1-sopropoxy-2,2,6,6-tetramethylpiperidin-4-ol was 70.4%,the mass fraction was 84.6%,and the separated of mass fraction was 99.8%;The yield of 1-butoxy-2,2,6,6-tetramethylpiperidin-4-ol was 59.3%,and the mass fraction was 67.4%;The yield of 1-isobutoxy-2,2,6,6-tetramethylpiperidin-4-o1 was 29.2%,and the mass fraction was 37.7%;The yield of 1-pentaoxy-2,2;6,6-tetramethyl piperidin-4-ol was 51.0%,and the mass fraction was 49.6%;The yield of 1-heptyloxy-2,2,6,6-tetramethylpiperidin-4-o1 was 51.8%,and the mass fraction was 71.7%.Tris(1-methoxy-2,2,6,6-tetramethylpiperidin-4-yl)phosphite was synthesized through esterification by using 1-methoxy-2,2,6,6-tetramethylpiperidin-4-ol and phosphorus trichloride as raw materials,chloroform as solvent,triethylamine as acid-binding agent.The results showed that the optimal conditions were as follows:the reaction time being 8 h,and the reaction temperature being 30℃,n(PCl3):n(piperidinol):n(triethylamine)=1:3:4.5,w(piperidinol):w(chloroform)=1:13.3;the pre-ferred purification method was to crystallize with anhydrous ethanol as solvent,and the preferred crystallization conditions were as follows:w(crude):w(anhydrous ethanol)=1:3.16,and the temperature was 0℃.Under the above conditions,the separated yield of the products was 83.4%,the molar content of phosphorus was greater than 99%,and the melting point was 99-101℃.