Synthesis of several aromatic aldazines

Chia sẻ: Minh Minh | Ngày: | Loại File: PDF | Số trang:6

Thêm vào BST

Báo xấu

15
lượt xem 2
download

Download Vui lòng tải xuống để xem tài liệu đầy đủ

Ten aromatic aldazines: 4-nitrobenzal-, 3-nitrobenzal-, 2-nitrobenzal-, 4-dimethylaminobenzal-, 4-methoxybenzal-, 3-methoxybenzal-, 4-fluorobenzal-, 4-chlorobenzal-, 4-bromobenzaldazine and 7-carboxymethoxy-6-hydroxy-3-sulfoquinolin-5-carbaldazine, were synthesized by condensing two equivalents of an appropriate aldehyde with one equivalent of hydrazine hydrate. The structure of the received aldazines was determined by IR, 1H-NMR and ESI MS spectra.

Chủ đề:

Bình luận(0) Đăng nhập để gửi bình luận!

Lưu

Nội dung Text: Synthesis of several aromatic aldazines

JOURNAL OF SCIENCE OF HNUE Chemical and Biological Sci., 2012, Vol. 57, No. 8, pp. 16-21 This paper is available online at http://stdb.hnue.edu.vn SYNTHESIS OF SEVERAL AROMATIC ALDAZINES Le Van Co1, Nguyen Dang Dat2 and Nguyen Huu Dinh2 1 Faculty of Chemistry, Tay Nguyen University 2 Faculty of Chemistry, Hanoi National University of Education Abstract. Ten aromatic aldazines: 4-nitrobenzal-, 3-nitrobenzal-, 2-nitrobenzal-, 4-dimethylaminobenzal-, 4-methoxybenzal-, 3-methoxybenzal-, 4-fluorobenzal-, 4-chlorobenzal-, 4-bromobenzaldazine and 7-carboxymethoxy-6-hydroxy-3-sulfoquinolin-5-carbaldazine, were synthesized by condensing two equivalents of an appropriate aldehyde with one equivalent of hydrazine hydrate. The structure of the received aldazines was determined by IR, 1 H-NMR and ESI MS spectra. Keywords: Aldazines, synthesis, IR, 1 H-NMR and ESI MS spectra. 1. Introduction Aldazines are functional organic compounds which are formed by a condensation reaction of two equivalents of an aldehyde with one equivalent of hydrazine [1]. Aldazines have been used for preparation of hydrazones [2, 3] and diazo compounds [4, 5]. They have been also used as sources for hydrazine produced in situ, for example, in the production of herbicide precursor 1,2,4-triazole [6]. Symmetrical and unsymmetrical aldazines are efficiently converted to 2,5-disubstituted-1,3,4-oxadiazoles by oxidation with bis(trifluoroacetoxy)iodobenzene (BTI) [7]: Received July 17, 2012. Accepted September 24, 2012. Chemistry Subject Classification: 10401. Contact Nguyen Huu Dinh, e-mail address: nguyenhuusp@yahoo.com 16
Synthesis of several aromatic aldazines Aldazines readily participate in some pericyclic reaction variants [8] and react with isocyanate in a double [3 + 2] cycloaddition involving both C=N bonds to form triazolotriazoles [8]: In view of the above mentioned findings, herein we report the synthesis of some substituted benzaldazines and polysubstituted quinoline-5-carbaldazine as precursors to the triazolotriazoles. 2. Content 2.1. Experiment The aldazines (1 - 10) were synthesized according to the following procedure: A solution of 2 mmol aromatic aldehyde and 1 mmol hydrazine hydrate in dry ethanol was refluxed for 3 - 4 h. The reaction mixture was then allowed to stand at room temperature for one hour. The resulting precipitate was collected and recrystallized. Some physical characteristics of the obtained compounds are presented in Table 1. Table 1. Some physical characteristics of the synthesized aldazines Ar−CH=N−N=CH−Ar Solvent for Compound Ar Form Mp (o C) recrystal Small DMSO/EtOH 1 yellow 259 1:4 crystals Small DMSO/EtOH 2 yellow 243-4 1:4 crystals Small DMSO/EtOH 3 yellow 233-4 1:4 crystals Small 4 rose EtOH 249-50 crystals 17
Le Van Co, Nguyen Dang Dat and Nguyen Huu Dinh Needle DMSO/EtOH 5 yellow 227-9 1:5 crystals Small DMSO/EtOH 6 yellow 194-5 1:4 crystals Needle 7 white EtOH 198-9 crystals Thin light DMSO/EtOH 8 217-8 yellow 1:5 crystals Thin light DMSO/EtOH 9 234-5 yellow 1:4 crystals Small DMSO/EtOH 10 yellow Decom. 1:3 crystals IR spectra were recorded using an IMPACT-410 NICOLET spectrometer with KBr discs at 400 - 4000 cm−1 . ESI mass spectra were recorded using an Agilent LC-MSD-Trap-SL series 1100 spectrometer. NMR spectra were recorded with the use of a Bruker AVANCE 500 MHz spectrometer, d6 -DMSO with TMS being the internal standard. 2.2. Results and discussion The substituted benzaldehydes which were used were commercially available while 7-carboxymethoxy-6-hydroxy-3-sulfoquinolin-5-carbaldehyde was synthesized from eugenoxyacetic acid in the three successive reaction steps presented in the following scheme: The structure of the aldehyde was determined by analyzing its IR, 1D-NMR, 2D-NMR and MS spectra and making comparisons with some spectra of its quinoline 18
Synthesis of several aromatic aldazines precursor and two arylhydrazones derivatives [9]. Aromatic aldehydes readily react with hydrazine to produce hydrazones. In our experiment the intermediate hydrazones condensed with a second equivalent of aldehyde to form the aldazines: The absence of absorption bands for stretching vibrations of NH2 and C=O groups in IR spectra of the aldazines, as in Figure 1 for example, indicates that the above reaction does not stop at the hydrazone formation step. Figure 1. IR spectrum of aldazine 8 For compounds 2, 3, 8, 9 and 10, the absorption band of azine C=N group is present at 1620 - 1627 cm−1 , but for the others this band and an absorption band of aromatic C=C groups overlap at ∼ 1600 cm−1 (Table 2). Table 2. The main absorption bands of aldazines 1 - 10, cm−1 1 2 3 4 5 6 7 8 9 10 3113 3091 3072 3080 3080 3050 3112 3053 3057 3050 νCH 2934 2915 2923 2925 2945 2912 2934 2990 2936 2975 2848 2850 2855 2860 2847 2850 2848 2945 2858 2850 1595 1627 1626 1599 1601 1603 1995 1621 1620 1621 νC=N , 1522 1529 1552 1580 1504 1525 1519 1586 1583 1593 νC=C 1450 1440 1492 1518 1461 1500 1450 1480 1480 1472 1 H-NMR spectra allow identification of the aldehyde moiety of the aldazines. For example, in the 1 H-NMR spectrum of aldazine 7 (Figure 2) the two multiplets 7.35 ppm, 2H, JH,H ≈ JF,H ≈ 7Hz and 7.95 ppm, 2H, JH,H ≈ 7Hz, JF,H ≈ 5Hz indicate a presence of 19
Le Van Co, Nguyen Dang Dat and Nguyen Huu Dinh F in the para position of the phenyl group. The singlet at 8.72 ppm (lower than the signal of the CH=O proton ∼ 1ppm) shows the presence of the CH=N group in the aldazine. Figure 2. The 1 H-NMR spectrum of aldazine 7 Table 3. 1 H-NMR signals of the examined compounds: , δ (ppm), J (Hz) H1 H2 H3 H4 H5 H6 Others 8.16 d, 8.36 d, 8.36 d, 8.16 d, 1 8.85 s - - J9 J9 J9 J9 8.71 t, 8.37 dd, 7.83 t, 8.32 d, 2 8.91 s - - J2 J 8; 2 J8 J8 8.15 d, 7.88 t, 7.80 t, 8.08 d, 3 8.96 s - - J8 J8 J8 J8 7.66 d, 6.78 d, 6.78 d, 7.66 d, H7 (6H): 4 8.52 s - J9 J9 J9 J9 3.01 s 7.95 m, 7.35 m, 7.35 m, 7.95 m, 7 8.72 s - - J 7; 5 J7 J7 J 7; 5 7.90 d, 7.58 d, 7.58 d, 7.90 d, 8 8.71 s - - J9 J9 J9 J9 7.83 d, 7.72 d, 7.72 d, 7.83 d, 9 8.70 s - - J 8.5 J 8.5 J 8.5 J 8.5 H7a 8.81 d, 8.79 d H8: 10 9.19 s - - (2H): J 1.5 J 1.5 7.36 s 4.83 s In the aldazines that were examined, there are two PhCH groups but they give rise 20
Synthesis of several aromatic aldazines to only one set of proton signals (Table 3). This is evidence of a symmetrical structure of the aldazines. The data in Table 3 are in accordance with the structure of the examined aldazines. In order to determine the final structure, ESI + MS of 7 as a presenter for the synthesized aldazines was recorded and analyzed. The pseudomolecular ion peak at m/z 245 corresponds to a molecular mass of 7 (244 au). 3. Conclusion Ten aromatic aldazines were synthesized by condensing two equivalents of an aromatic aldehyde with one equivalent of hydrazine hydrate. The structure of resulting aldazines was determined making use of IR, 1 H-NMR and ESI MS spectra. Acknowledgment. This work was supported by the National Foundation for Science and Technology Development (NAFOSTED) of Vietnam. REFERENCES [1] G. P. Moss, P. A. S. Smith, D. Tavernier, 1995. IUPAC Recommendations. Pure Appl. Chem. 67 (8-9): 1307 - 75. [2] A. C. Day, M. C. Whiting, 1970. Org. Synth. Coll. Vol. 6: 10. [3] H. Staudinger, Gaule, Alice, 1916. Ber. Dtsch. Chem. Ges. 49 (2): pp. 1897-1918. [4] A. C. Day, P. Raymond, R. M. Southam, M. C. Whiting, 1966. J. Chem. Soc. pp. 467-69. [5] S. D. Andrews, Day, P. Raymond, M. C. Whiting, 1970. Org. Synth. 50: 27. [6] Nagata, Nobuhiro; Chiharu Nishizawa & Toshikiyo Kurai, 1999. US Patent 6002015, 12-14. [7] Zhenhua Shang, John Reiner, Junbiao Chang , Kang Zhao, 2005. Tetrahedron Letters, 46 (11) p. 2701. [8] Henri Ulrich, 2009. Cumulenes in Click Reactions. John Wiley & Sons. [9] Le Van Co, Tran Thi Thu Trang, Nguyen Minh Hai, Nguyen Huu Dinh, 2012. Journal of Chemistry, p. 50 (accepted). 21