New Method for Nucleophilic Substitution on Hexachlorocyclotriphosphazene by Allylamine Using an Algerian Proton Exchanged Montmorillonite Clay (Maghnite-H+) as a Green Solid Catalyst

Nucleophilic substitution on hexachlorocyclotriphosphazene (HCCTP) with allylamine in order to give hexa(allylamino)cyclotriphosphazene (HACTP) is performed for the first time under mild conditions by using diethylether as solvent to replace benzene due to its toxicity. The reaction time is reduced to half and also performed at room temperature but especially in the presence of an eco-catalyst called Maghnite-H+. This catalyst has a significant role in the industrial scale. In fact, the use of Maghnite is preferred for its many advantages: a very low purchase price compared to other catalysts, the easy removal of the reaction mixture. Then, Maghnite-H+ is became an excellent catalyst for many chemical reactions. The structure of HACTP synthesized in the presence of Maghnite-H+ to 5% by weight is confirmed by 1H-NMR, 13C-NMR, 31P-NMR (Nuclear magnetic resonance) and FTIR (Fourier Transform Infrared spectroscopy). MALDI-TOF (Matrix-Assisted Laser Desorption/Ionisation-time-of-flight mass spectrometry) is used to establish the molecular weight of HACTP which is 471 g/mol. DSC (Differential Scanning Calorimetry) and TGA (Thermogravimetric Analysis) show that HACTP is a crystalline product with a melting point of 88 °C. It is reactive after melting but is degraded from 230 °C. Copyright © 2016 BCREC GROUP. All rights reserved


Introduction
Phosphazenes are inorganic compounds which belong to the most important class of cy-clic or linear structure of general formula (R2P=N)n.The degree of polymerization "n" may vary from 3 to more thousand.R can be a halogen, alkyl, aryl, amine, alkoxy, and other groups.Cyclophosphazenes are cyclic trimers (R2P=N)3 and when R represents halogen Cl, there will be formation of hexachlorocyclotriphosphazene (HCCTP) (N=Cl2P)3 (Figure 1).HCCTP is prepared from ammonium chloride and pentachloride phosphorus.It is an inorganic compound which has a basic character [1,2].The physical properties of HCCTP are summarized in Table 1.
Nucleophilic substitution on HCCTP is the main way to the synthesis of hybrid compounds (organic-inorganic) called organophosphazenes [3][4][5].The choice of the monomer organophosphazene is justified by the importance of its use in the production of toric joint, gas pipes and a variety of joints, for storing and transferring oils and fuels.Some derivatives compounds are microcrystalline (influence of R) and can be used in the production of flexible films and fibers [6,7].Many derivatives are biocompatible, biodegradable and some of them are bioactive and are studied for their potential medical applications [8][9][10].There are also polymers synthesized from organophosphazenes monomers [11][12][13] which have exceptional elastomers properties [14] and are used as solid electrolytes in the production of rechargeable batteries of low weight [15][16][17].
These organophosphazenes have a great importance by their many applications, so a particular interest is given to nucleophilic substitution on hexachlorocyclophosphazene (HCCTP) by allylamine according to the method of Christova et al. [18] to give hexa(allylamino)cyclotriphosphazene (HACTP) but operating under milder process conditions.In fact, the originality of this work consists in the synthesis of HACTP using a clay called "Maghnite-H+" as a catalyst [19].It is very ecological, economic and regenerable by simple filtration.The synthesis method of Christova et al. [18] is also modified by replacing benzene, which is carcinogenic, by diethylether as solvent.

Preparation of Maghnite-H+
The preparation of Maghnite-H+ was carried out by using a method similar to that described by Belbachir and coworkers [20].In an Erlenmeyer flask of 500 mL, 30 g of crushed and dried raw-maghnite were dispersed in 120 mL of distilled water, the mixture was stirred for 2 hours.After this time, 100 mL of 2.5 M sulfuric acid solution was added, the solution thus obtained was kept under stirring for two days at room temperature.Then, the product was filtered and washed with distilled water until complete disappearance of traces of acid.Once purified clay, it was dried overnight in an oven at 105 °C, and then stored in vials well saddled against moisture and any impurity.

Synthesis of hexa(allylamino) cyclotriphosphazene
Nucleophilic substitution on HCCTP (N3P3Cl6) by allylamine (NH2-CH2-CH=CH2) is performed as is described by Christova et al. [18].To a stirred solution of 3 mL (0.040 mol) of allylamine in 3.33 mL of benzene, 1 g (0.0028 mol) of HCCTP dissolved in 5 mL of benzene was added dropwisely.The reaction mixture was stirred for 24 hours at room temperature.The volatile solvents were removed in a rotary evaporator and the remaining solid was ex-

Synthesis of hexa(allylamino) cyclotriphosphazene using Maghnite-H+
The synthesis of HACTP was conducted from HCCTP and allylamine as starting materials with the addition of a catalyst which was Maghnite-H+ at 5% by weight and using diethylether as solvent to replace benzene.The reaction time was reduced to 12 h.At the end of the reaction, chloroform was added to the solution and then filtered to separate the product from Maghnite-H+.Then, the final product was purified by recrystallization.The yield was 74%.Operating conditions of the synthesis of HACTP, according to the method of CHRIS-TOVA and in the presence of Maghnite-H+, were summarized in Table 2.

Characterization of products
1 H-NMR, 13 C-NMR and 31 P-NMR spectra were recorded in CDCl3 solution under room temperature on an AM 300 FT Bruker spectrometer using tetramethylsilane as internal standard.FTIR absorption spectra were recorded on an MATTSON GENESIS II FT-IR spectrometer using the KBr pressed disc technique.Thermogravimetric analyzes were recorded on a SETARAM Labsys TG-DTA/DSC (room temperature -1600 °C) with a nitrogen sweep of 200 mL/min at a heating rate of 10 °C/min.DSC measurements were carried out on a TA instrument (TGA Q500), according to the following program: products were first heated from ambient temperature to 250 °C at 10 °C/min maintained at this temperature during 5 min then cooled to 25 °C at 20 °C/min.The MALDI-TOF spectra have been carried out in a Bruker microflex, the samples were prepared in CHCl3 with Dithranol as matrix.

Characterization of the catalyst (Maghnite-H + )
Table 3 shows the variation of the elementary chemical composition of the Raw-Maghnite before and after its activation with 2.5 M sulfuric acid solution.It is observed that the acid treatment leads to a decrease in Al2O3 and an increased percentage of SiO2 in the material.
The X-ray powder diffraction profiles (Figure 2) exhibit the increase in basal spacing from 12.5 Å in the Raw-Maghnite, characteristic of a single water layer between the sheets, to a 15.02 Å value in Maghnite-H + for two interlamellar water layers reflecting the changes in interlayer cation and its associated hydration state as a result of the acid treatment.
The FTIR spectra of the treated Maghnite (Figure 3) confirmed the montmorillonite structure of the Maghnite-H + .The characteristic absorption of the OH groups linked to the octahedral aluminum is observed by a broad band between 3200 cm -1 and 3400 cm -1 .The strong band at 1007 cm -1 corresponds to the Si-O stretching vibration in the tetrahedral layer.Angular deformation bands at 518 and 449 cm -1 are assigned to the type links of Si-OM smectites, M may be Mg, Al or Fe.

Characterization of HATCP catalysed by Maghnite-H +
Figure 4 shows that the most characteristic bond in the FTIR spectrum of HCCTP is the band of N=P group degenerated in the area of 1200 cm -1 .This frequency is not only influenced by single and double bond, but also by the electronegativity of the groups linked to phosphorus.The characteristic peaks appeared at 505 and 594 cm -1 are assigned to two P-Cl bonds.When the Chloro groups of HCCTP are substituted with allylamine, the resulting HACTP has

Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2), 2016, 154
Copyright © 2016, BCREC, ISSN 1978-2993  5.The spectrum shows characteristic peaks at 3450 cm -1 corresponding to N-H groups, and at 1644 and 967 cm -1 for C=C bonds.The absorption band at 1204 cm -1 assigned to N=P group in the starting material becomes 1254 cm -1 in HACTP, confirming that Cl atom attached to phosphorus has been substituted by another electrondonating group, which explains the increase in the value of the absorption band assigned to the group P=N.
The chemical structure of HATCP is further supporter by 1 H-NMR, 13 C-NMR and 31 P-NMR spectra.The different signals observed in the 1 H-NMR spectrum of Figure 6 and which are summarized in Table 4, correspond to the groups shown in the structural formula of HACTP catalyzed by Maghnite-H + at 5%wt.The resonance peak at 2.276 ppm is assigned to proton linked to Nitrogen (N-HA).This peak confirm that nucleophilic substitution on HCCTP has been occurred.The 13 C-NMR spectrum clearly shows three resonance peaks with their carbons assigned in Figure 7.In the 31 P-    8-A), there is one peak appeared at 16 ppm.For comparison, the 31 P-NMR of HCCTP [21], also in Figure 8-B, has resonance peak located at 20 ppm.The molecular weight of HACTP determined from the mass spectrometry is 471 (Figure 9).Other significant observation on the mass spectrum of HACTP is its fragmentation to m/e 422, 375, 331, and 226.
The TGA data of HACTP shown in Figure 10 indicates a two-stage degradation behavior.The first stage of degradation at around 230-320 °C.It is proceeded by the cleavage of two allylamine groups remaining 31.29 wt% residue, and then proceeded with the cleavage of another two allylamine groups after 400 °C.The DSC result shown in Figure 11 indicates that HACTP is a highly crystalline material with a melting temperature of 88.1 °C.It is mildly reactive after melt with the maximum reaction temperature at 198.9 °C.

Conclusions
In this work, a new synthetic method was developed to produce HACTP using friendly, green, ecologic and non toxic catalyst clay as proton source avoiding the use of benzene as a solvent because it is carcinogenic, so it is replaced by diethyl ether which is less toxic.The synthesis of HACTP is also carried out at room temperature with a halving of reaction time from 24 to 12 h which is very attractive from an industrial point of view.The simplicity of the synthesis method, good catalytic properties of the support catalyst Maghnite-H + and the use of non toxic solvent make this an attractive w a y f o r t h e s y n t h e s i s o f hexa(allylamino)cyclotriphosphazene.