Synthesis Of Ferrocenemethyl-1,2,3-triazoles And Their Combustion Catalytic Properties

Ferrocene alkyl derivatives are a class of burning rate catalysts(BRCs)that are widely used,can increase burning rates of propellants,and can improve the process and mechanical properties of the propellants.They have been widely used in composite solid propellants.Among them,catocene,which has been widely used,still has problems such as easy migration after long storage time.This high migration tendency will shorten service life of the propulsion systems,increase defense expenditure.It will increase internal pressure of the power system and even lead to potential risk of explosion during the combustion process.Therefore,it is of great significance to develop new types of ferrocene-based burning rate catalyst with low migration trends and excellent comprehensive performance.To overcome problems of the currently used ferrocene-based burning rate catalysts such as easy migration,cumbersome synthesis,and low heat-releasing,we proposed an improved approach for synthesizing ferrocene-based burning rate catalysts using "click reaction"."Click reaction" belongs to a green synthesis method,which has the advantages of low pollution and high yields.The "click reaction" synthetic methodolody is helpful for solving the scaling-up problem of some ferrocene-containing BRCs.By means of this method,the introduction of nitrogen-rich groups will increase energy level of the propellants,and the introduction of polar atoms will improve the anti-migration performance of the catalysts.Based on the above advantages,we have synthesized 35 new ferrocene compounds through "click reaction".The main research work is as follows:(1)10 kinds of phenols,11 kinds of benzoic acids,6 kinds of fatty alcohols,8 kinds of fatty amines and aromatic amines compounds were selected as precusors to react with bromopropyne to form the corresponding terminal alkyne compounds.Ferrocenylmethanol reacts with sodium azide to give azidomethylferrocene.The reaction of alkyne-terminated compounds with azidemethylferrocene by "click reaction"generated 35 novel ethers,carboxylic esters and amines containing ferrocenylmethyl-1,2,3-triazolyl groups(1-35).The structures of the new compounds were characterized by 1H NMR,13C NMR,FT-IR,UV/Vis and elemental analysis.The single crystal structures of four compounds(1,9,13,and 16·CH2Cl2)were determined by single crystal X-ray diffraction.(2)The thermal stability of 35 new compounds was tested by TG technique.The results showed that the initial decomposition temperatures of 14 compounds were close to 300?.Compared with the most ferrocenyl ionic compounds we reported previously,the thermal stability of the new compounds is dramatically higher.The volatility of 16 compounds was evaluated by TG at 70?.The results showed that the weight loss rate of the new compound was 0.2%?1.5%.The maximum weight loss rate of the tested compounds was only one-third of that of catocene(4.5%),indicating that the volatility of the new compound is significantly low compared to catocene.The cyclic voltammetry was used to test the redox properties of the 35 new compounds at a scan rate of 0.1-0.3mV/s.The results showed that 19 compounds exhibit good redox reversibility.16 compounds were selected for migration test,with ferrocene and catocene as referee.As a result,it was found that the migration distances of the 16 selected compounds do not exceed 0.2 cm after 4 weeks aging.The migration distances of ferrocene and catocene after 4 weeks were 2.7 cm and 1.9 cm,respectively,indicating that the new compounds have much better anti-migration properties compared to ferrocene and catocene.(3)DSC technique was employed to evaluate catalytic effects of the 35 compounds on the thermal decomposition of AP,RDX and HMX.The results showed that each series of compounds show best catalytic effect with 5 wt.%addition in AP.The tests further showed that all new compounds display good catalytic effects on AP thermal degradation with optimized addition amounts.Compared with pure AP(406.6?),the decomposition peak temperatures of the mixtures have been shifted forward by about 50?,and the released heats of the mixtures(-1335.83 J·g-1?-1915.00 J·g-1),are significantly higher than that of the pure AP(-746.53 J·g-1).Among them,the released heat of the mixtue of AP+5 wt.%31(aniline-derived compound)an reach up to-1915 J.g-1,an increase of more than 1.5 times.The mixtures of the new compounds with RDX can release heat between-862.6 J·g-1?-1757.33 J·g-1,much higher than that of pure RDX(-830.60 J·g-1).The RDX decomposition peak temperature(237?)is shifted forward by 0.1?-19.4?with the addition of the new compounds.The tested results implied that the new compounds showgreat catalytic effects on RDX thermal disintergration.The mixtures of RDX and compound 23,29,31 or 33 released more than 1600 J·g-1 heat,indicative of better catalytic performance among the 35 new compouds 15 compounds have a certain catalytic effects on HMX thermal decomposition according to the tested results.In summary,all novel ferrocenylmethyl 1,2,3-triazolyl compounds exhibit catalytic effects on thermal degradation of AP and RDX,but only a few new compouds show certain catalytic activities in the thermal decomposition of HMX.So improving catalytic effects of ferrocenyl compounds on HMX thernal degradation is our further research direction.In general,the newly synthesized ferrocenylmethyl 1,2,3-triazolyl compounds have the advantages of high anti-migration performance and good catalytic performance on thermal disintergration of the oxidizers,and display potential application prospects.