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Reactions of Cyclochlorotriphosphazatriene with 1-Amino-2-Propanol

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Reactions of Cyclochlorotriphosphazatriene with 1-Amino-2-Propanol Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 22 (3), 1033-1047, 2018 SAKARYA UNIVERSITY JOURNAL OF SCIENCE e-ISSN: 2147-835X http://www.saujs.sakarya.edu.tr Received 26.01.2018 Doi Accepted 10.16984/saufenbilder.384736 10.05.2018 Reactions of cyclochlorotriphosphazatriene with 1-amino-2-propanol. Calorimetric and spectroscopic investigations of the derived products. Sedat TÜRE11*, Rafıg GURBANOV2, Murat TUNA3 Abstract Reactions of hexachlorocyclotriphosphazatriene, N3P3Cl6 (1) with 1-amino-2-propanol (2), in (1:1, 1:2 and 1:3) mole ratios, in excess of NaH, in THF and acetonitril solutions yield a total of 6 novel products: one mono-open chain, N3P3Cl5[HN-CH2-CH(CH3)-OH] (3); one monospiro, N3P3Cl4[O-CH(CH3)-CH2-NH] (4); one trans bis-open chain, N3P3Cl4[HN- CH2CH(CH3)-OH]2 (5); one dispiro, N3P3Cl2[O-HC(CH3)-CH2-NH]2 (7); one tri-open chain, N3P3Cl3[HN-CH2CH(CH3)-OH]3 (6); and one tri-spiro, N3P3[O-HC(CH3)-CH2-NH]3(8) derivatives. These compounds have interesting structural aspects as well as physical properties. Their structures were established by elemental analysis, TL-MS, 31P and 1H NMR spectral data. Stability constants were determined using a simple potentiometric titration. For evaluation of melting behavior and purity of derivatives (7) and (8), thermal transition peaks and their corresponding enthalpies were determined via DSC technique. Spectroscopic data, product types and relative yields are compared with those of the previously investigated derivatives of N3P3Cl6 (1) with aliphatic difunctional reagents. Key words: Hexachlorocyclotriphosphazene, 1-amino-2-propanol, spiro compounds, open chain compounds, DSC analysis 1. INTRODUCTION been studied for their properties both as linear polymers [1-5], and cyclic structures [6-29, 30]. Their general electronic Due to their substitution patterns, structure has also been studied [11], phosphazenes potentially have more focusing on the interactions between the variations than carbon analogs such as nitrogen and phosphorus atoms linear or benzene that are limited because these allow cyclic geometries. Intramolecular reactions only one substitution in a particular location of short chain difunctional nucleophiles, in the ring. In the past, phosphazenes have *Corresponding Author 1 Bilecik Şeyh Edebali University, Art and Science Faculty, Departmant of Chemistry, [email protected] 2 Bilecik Şeyh Edebali University, Art and Science Faculty, Departmant of Molecular Biology and Genetic, [email protected] 3 Sakarya University, Art and Science Faculty, Departmant of Chemistry, [email protected] 1033 Türe et al. / Reactions of cyclochlorotriphosphazatriene with 1-amino-2-propanol. Calorimetric and spectroscopic investigations of the derived products such as amino-alcohols and mercapto- to form geminal open chain or spirocyclic alcohols with trimer (NPCl2)3 (1), can yield structures [16-19]. Third, chlorine units on geminal/non-geminal open-chain or adjacent phosphorus atoms may be replaced spirocyclic products [12-15]. First, to produce non-geminal open chain dinucleophil may replace only one chlorine products 18-19, 35]. General replacement atom to produce open chain structure. patterns of 1-amino-2-propanol formations Second, the dinucleophile may replace two are shown in Figure 1. chlorine atoms at the same phosphorus atom Figure 1. Substitution patterns of cyclotriphosphazene (1) withshorter chain dinucleophiles.X and Y are heteroatoms (i.e., O or N). Amino alcohols contain both an amine and tendency to donate electrons or react at the an alcohol group. Amino alcohol electron-poor sites on the phosphorus derivatives have been used as coupling atoms, and the likelihood substitution partners in addition to catalysts in the patterns of compound formation. In synthesis of many compounds. addition, melting and crystallization Enantiomerically pure beta-amino alcohols behavior of compounds 6 and 7 were play an increasingly important role in characterized. pharmaceutical therapeutics and as chiral The reactions of cyclophosphazene (1) with auxiliaries in organic synthesis. Amino the 1-amino-2-propanol (2) in excess of alcohol derivatives are currently being NaH (Figure 2) gave predominately spiro studied for modulating antimicrobial and derivatives (4, 7, 8) as well as giving mono- antifungal activities and the physiochemical (3), bis- (5) and tris- (6) open chain properties of drug molecules. The amino products. Similar findings were reported alcohol group is found in many antibiotics, with shorter chain lenght of difunctional such as ethambutol, which is used in the reagents e.g.1,2-ethane-diamine and amino- treatment of tuberculosis. The additions of alcohols [32]. With longer chain lengths of 1,2-carbonyl compounds, ring closure the spacer (CH2)n group in difunctional reactions, conjugate additions and α- reagents, bridged compounds predominated functionalization are carried out efficiently to intramolecular formations [30-35]. with β-amino alcohols as catalysts. The These results are in contrast to the reactions availability of β-amino alcohols from a of shorter chain diamines, where are for chiral pool (eg, L-amino acids) makes them thermodynnamic reasons generally an attractive class of versatile promoters for spirocyclic products were synthesised [33]. use in modern organic synthesis. In this paper we strive to understand heteroatom chain length, nucleophilic Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 22 (3), 1033-1047, 2018 1034 Türe et al. / Reactions of cyclochlorotriphosphazatriene with 1-amino-2-propanol. Calorimetric and spectroscopic investigations of the derived products Figure 2. Structures of cyclophosphazene derivatives with 1- amino-2-propanol. compounds (3-8) were characterized by 1 31 2. RESULTS AND DISCUSSION elemental analysis, MS, H and P NMR spectroscopy and the results are provided as part of the analytical data in the The reactions of N3P3Cl6 (1) with 1-amino- experimental section. Structure of derived 2-propanol in 1:1:2, 1:2:4 and 1:3:6 compounds are displayed in Figure 2. stoichiometries gave the following isolated and characterized derivatives: one mono- 2.1. Synthesis and characterization of open chain compound, N3P3Cl5[NH-CH2- compounds 3-8. CH(CH3)-OH] (3, 19%); one trans bis-open chain compound, N3P3Cl4[NH-CH2- The selectivity of the substitution reactions CH(CH3)-OH]2 (5, 15%); one tri-open of trimer (1) with difunctional regeants is chain compound, N3P3Cl3[NH-CH2- strongly depended on the temperature [25], CH(CH3)-OH]3 (6, 16%); one mono-spiro solvent and the type of nucleophilic compound, N3P3Cl4[O-CH(CH3)-CH2-NH] regeants [24-25]. Solvent effect plays an (4, 53%); one dispiro compound, important role in determining the stereo and N3P3Cl2[O-CH(CH3)-CH2-NH]2 (7, 37%,); regio sellective control on the and one tri-spiro compound, N3P3[O- cyclophosphazene rings [22-25]. CH(CH3)-CH2-NH]3 (8, 26%). Mono spiro derivative (4, 53%) is isolated in larger In general, at low temperature with a shorter amount than the other products. Isolated chain length reagent, the nucleophilic Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 22 (3), 1033-1047, 2018 1035 Türe et al. / Reactions of cyclochlorotriphosphazatriene with 1-amino-2-propanol. Calorimetric and spectroscopic investigations of the derived products substitution takes place on different phosphorus atoms and giving rise to open chain products. Here, in our nucleophilic reagent, the amino groups are generally more nucleophilic than hydroxyl groups, so that when an amine and an alcohol (a compound containing a hydroxyl group) are mixed together with a common electrophile in a certain amount, the electrophile almost only enters the reaction with the amine As mentioned, two structures are possible groups. Likewise for compounds containing depending on whether the exocyclic both an amino group and a hydroxyl group, nitrogen atoms have a cis or trans an electrophile typically reacts at the amine disposition. Compound 7 is tentatively moiety of the molecule. assigned to the trans structure due to its higher TLC R value. In general, the TLC R Reactions at the hydroxyl group is often not f f value of the trans-aminochlorocyclo- possible as long as the amino group is not triphosphazene derivative is greater than changed in a separate step using a protecting the cis analogue [23, 33]. group to previously react [2]. As noted, it is estimated that the first substitution takes Dispiro derivatives exhibit AB2 type place over the amine group and later on the spectra. Therefore, the 31P {1H} NMR hydroxyl group. However, the situation is spectrum of compound 7 is AB2 type and different when working with phosphazenes. gives rise to very close five line structure. Due to the presence of chlorine atoms (Cl or 31P NMR proton-coupled spectrum of the Cl2) on the phosphorus atoms and since the structure allows identification of the lines phosphorus atoms are still open to new due to the ≡Pspiro and ≡PCl2 groups, where substitution reactions after the initial spiro group split into further lines. Proton displacement (Cl with amino group), it is coupling experiments as well as comparison possible for hydroxyl group to attack on with the analogues diols and diamine phosphorus atoms for second substitution. derivatives [24, 25] allow precise Therefore, we were able to obtain geminal assignment of the structure. spiro and geminal/non-geminal open chain Compound, N3P3Cl4[O-CH(CH3)-CH2- derivatives. Unless you make a very special NH] (4), whose analysis and mass spectrum changes in reaction conditions, it is unlikely showed that this can be either mono spiro or to obtain ansa type cyclic structure with a its ansa isomer. Previous experience with shorter chain length of nucleophils. these two isomers shows that these could have in principle two structures: Spiro or 2.2. 31P NMR spectroscopic data ansa. The ansa compound has an AB2 type 31 spectrum, while that of the spiro isomer is P NMR spectra of resulting compounds 31 with 1-amino-2-propanol showed the of the A2X. P (-H) coupling affects the B2 part of the former and X part of the later predominance of spiro structures with A2B, giving further splitting on the spectrum.
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