Synthesis Of Tris(1-alkoxy-2,2,6,6-tetramethylpiperidin-4-yl) Phosphite

Highly efficient,non-toxic,non-halogen,low smoke,and both good light and heat stabilization,N-alkoxy hindered amines（NORs）are normally considered great potential multi-functional green flame retardants.However,as the flame retarded effect of the current varieties is only obvious in the polypropylene thin products,in addition,chemical structures and synthesis processes of them are extremely complex,a novel type of N-alkoxy hindered amines-tris（1-alkoxy-2,2,6,6-tetramethyl piperidine-4-yl）phosphites were designed and synthesized according to the flame retarded mechanism.In the paper,the synthesis processes of tris（1-cyclohexyloxy-2,2,6,6-tetramethyl piperidine-4-yl）phosphite,tris（1-ethoxy-2,2,6,6-tetramethyl piperidine-4-yl）phosphite and tris（1-propoxy-2,2,6,6-tetramethyl piperidine-4-yl）phosphite were studied.The results revealed that tris（1-alkoxy-2,2,6,6-tetramethyl piperidine-4-yl）phosphite could be efficiently synthesized through O-alkylation,esterification with PCl3,by using 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy（ZJ-701）as the starting material.1-Cyclohexyloxy-2,2,6,6-tetramethylpiperidine-4-ol（intermediate）was synth esized by a free radical reaction by using ZJ-701 and cyclohexane as raw materials,tert-butyl hydroperoxide（TBHP）as oxidant,CuCl2 as catalyst,ethanol as cosolvent.Its optimal conditions were: n（ZJ-701）:n（TBHP）:n（CuCl2）:n（cyclohexane）: n（ethanol）= 1:9.6:0.32:13:34,the reaction time being 9 h,and the reaction temperature being 65°C.Under the above conditions,the yield of the products was 55.46% and the purity was 98.49%.Tris（1-cyclohexyloxy-2,2,6,6-tetramethyl piperidine-4-yl）phosph ite was synthesized through esterification by using 1-cyclohexyloxy-2,2,6,6-tetramethyl piperidine-4-ol and phosphorus trichloride as raw materials,chloroform as solvent,triethylamine as acid-binding agent.Its optimal conditions were: n（PCl3）:n（intermediates）:n（triethylamine）= 1:3:9,the reaction time being 8 h,and the reaction temperature being 32°C.Under the above conditions,the yield of the products was 53.85% and the molar content of phosphorus was 98.04%.1-Ethoxy-2,2,6,6-tetramethyl piperidine-4-ol（intermediate）was synthesized through a free radical reaction by using ZJ-701 and butanone as raw materials,30% hydrogen peroxide as oxidant,CuCl as reducing agent.Its optimal conditions were: n（ZJ-701）:n（butanone）:n（H₂O₂）:n（CuCl）= 1:12:5:0.056,the reaction time being 18 h,and the reaction temperature being 30°C.Under the above conditions,the yield of the products was 64.66% and the purity was 98.91%.Tris（1-ethoxy-2,2,6,6-tetramethyl piperidine-4-yl）phosphite was synthesized through esterification by using 1-ethoxy-2,2,6,6-tetramethyl piperidine-4-ol and phosphorus trichloride as raw materials,chloroform as solvent,triethylamine as acid-binding agent.Its optimal conditions were: n（PCl3）:n（intermediates）: n（triethylamine）= 1:3:9,the reaction time being 12 h,and the reaction temperature being 50°C.Under the above conditions,the yield of the products was 71.17% and the molar content of phosphorus was 99.01%.1-Propoxy-2,2,6,6-tetramethyl piperidine-4-ol（intermediate）was synthesized through a free radical reaction by using ZJ-701 and butyraldehyde as raw materials,30% hydrogen peroxide as oxidant,CuCl as reducing agent.When n（ZJ-701）: n（butyraldehyde）:n（H₂O₂）:n（CuCl）= 1:4.8:2.6:0.043,the reaction time was 24 h,and the reaction temperature was 18°C,the yield of the products was 54.94% and the purity was 98.61%.Tris（1-propoxy-2,2,6,6-tetramethyl piperidine-4-yl）phosphite was synthesized through esterification by using 1-propoxy-2,2,6,6-tetramethyl piperidine-4-ol and phosphorus trichloride as raw materials,chloroform as solvent,triethylamine as acid-binding agents.When n（PCl3）:n（intermediates）:n（triethylamine）= 1:3:9,the reaction time was 12 h,and the reaction temperature was 50°C,the yield of the products was 74.74%,and the molar content of phosphorus was 98.04%.