Synthesis Of Fullerene Pyrrolidine Bisaddition Derivatives And Their Stability To NG/NG

The NC/NG is widely used in double-base propellants,and the NC/NG consist mainly of nitrate esters such as nitrocellulose(NC)and nitroglycerin(NG).The NC/NG is easy to decompose due to the low bond energy of nitrate bond(CO-NO₂).The nitrogen oxide gas and nitrogen oxygen free radicals produced during the thermal decomposition of the NC/NG can further promote the autocatalytic decomposition of the NC/NG,so the stabilizer needs to be added to the NC/NG.Most of the compounds produced by the interaction between the traditional stabilizers and the NC/NG contain lots of carcinogenic substances.At the same time,the thermal stability of the traditional stabilizers is not good,and the stability to the NC/NG in high temperature environment is difficult to adapt to the complex and changeable environment of modern war.Therefore,it is imperative to develop new stabilizers with low toxicity or non toxicity and excellent thermal stability.Fullerene(C₆₀)is known as the sponge of absorbing free radicals.It combines with the functional groups in the structure of traditional stabilizer to form a new stabilizer with excellent performance.There are obvious differences in the stability of different fullerene-based stabilizers.It is of great significance to study the relationship between the structure and stability of fullerene-based stabilizers and the mechanism of stabilization for the design and synthesis of new stabilizers.This paper mainly includes the following three aspects:(1)N-(4-methoxy)phenylglycine was prepared used p-methoxyaniline and ethyl chloroacetate,and then N-(4-methoxy)phenylglycine and fullerene were used as raw materials to synthesize a fullerene pyrrolidine monoaddition derivative and four new fullerene pyrrolidine bisaddition isomers with similar structure by Prato reaction.Their molecular structures were characterized by UV-Vis,NMR,X-ray single crystal diffraction and HRMS.(2)The synthesized fullerene pyrrolidine derivatives and fullerenes were used as stabilizers of NC/NG,respectively.The DSC results showed that these fullerene derivatives had good compatibility with NC/NG.In addition,the weight loss tests,vacuum stability test(VST),methyl violet test and accelerating rate calorimeter(ARC)test experiments showed that the stability of fullerene pyrrolidine double adduct to NC/NG was better than that of fullerene pyrrolidine single adduct and fullerene.Moreover,the stability to NC/NG of four fullerene pyrrolidine adducts with different structures was also significantly different,specifically e-edge>trans-2>cis-2>trans-3.(3)FT-IR and EPR results showed that fullerene stabilizers could effectively eliminate the nitrogen oxides and nitroxide radicals produced by the decomposition of NC/NG,inhibited the autocatalytic decomposition of NC/NG in time,and prolonged the safe storage time of NC/NG.The results of stability test and EPR test showed that the stability of these fullerene-based stabilizers was consistent with their NO·scavenging efficiency:e-edge>trans-2>cis-2>trans-3>monoaddition>C₆₀.