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51. |
Pyrolysis ofN1,N3-Diaryltriazene 1-Oxides |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 7,
1997,
Page 406-407
Ahmed Moukhtar Nour El-Din,
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摘要:
Pyrolysis of N1,N3-Diaryltriazene 1-Oxides$ Ahmed Moukhtar Nour El-Din,*a Shaaban Kamel Mohamed,b Dietrich Do�â pp,b Alfred Gollochc and Gudrun Steudec aChemistry Department Faculty of Science, El-Minia University, El-Minia, A. R. Egypt bFachgebiet Organische Chemie, Gerhard-Mercator Universita�â t-GH, Duisburg, Germany cFachgebiet Instrumentelle Analytik, Gerhard-Mercator Universita�â t-GH, Duisburg, Germany Pyrolysis of the 1,3-dipole unsymmetrical diaryltriazene 1-oxides in acetonitrile and toluene shows that these compounds may serve as a source of aryl radicals.Previously, we have reported that unsymmetrical diaryl- triazene 1-oxides did not undergo 1,3-dipolar cycloaddition reactions with tetracyanoethylene, instead charge-transfer complexes were formed.1 On the other hand, photolysis of these oxides led to their decomposition. 2-Hydroxyazo- benzene, mono- and di-substituted biaryls were produced.2 Therefore, it seemed desirable to study the thermal e€ect on this 1,3-dipole system in organic solvents.This paper presents our results obtained from the pyrolysis of various N1,N3-diaryltriazene 1-oxides in acetonitrile and toluene. Nitrogen was bubbled through solutions of 0.5 mmol of triazene 1-oxides 1 in dry acetonitrile to remove the oxygen, and the sealed ampoules were heated for 4 h (see Experimental section). The reaction mixtures were identiRed and quantiRed through gas chromatography coupled with mass spectrometry (GC-MS), by comparing the peak areas and fragmetation patterns of the products with those of authentic samples. As shown in Scheme 1, pyrolysis of compounds 1 in acetonitrile led to the formation of azoxybenzene 2 (major product 10.3�}36%), azobenzene 3, diarylamines 4, biaryls 5 and arenes 6.In addition to these ideniRed compounds a multicomponent mixture is produced. The individual com- ponents of this mixture are characterized by higher retention times and therefore probably of higher molecular weight.None of these peaks has so far been identiRed. Earlier Morgan and Walls3 had proposed that pyrolysis of 1,3-di-p-tolyltriazene proceeds via fragmentation into p-polylaminyl radicals. In addition Hardie and Thomson4 found that the tautomerism of asymmetric triazenes results in the production of two di€erent aryl radicals and two arylaminyl radicals. This partitioning phenomenon could not be observed by Morgan and Walls3 because their triazenes were symmetri- cally substituted, and it will probably not occur in this investigation because an oxygen atom shift would not as easy as a (solvent mediated) hydrogen shift.In accordance with the literature results above, a rational formation of azoxybenzene 2, azobenzene 3, diarylamines 4, biaryls 5 and arenes 6 is presented in Scheme 2 featuring radical pathways throughout. Pyrolysis of triazenes 1-oxides 1a�}d may lead to cleavage into the corresponding hydroxyphenylaminyl and aryl- diazenyl radicals.The latter may undergo loss of nirogen to form an aryl radical and/or to react with hydroxyphenyl aminyl radical to form either compound 8 or nitrosobenzene with the aryldiimine 7. It has been reported that triazene 1-oxides may exist in a tautomeric mixture with their hydroxytriazene form.5 The N0OH tautomer of 1 may be envisaged as the 1:1 adduct of aryldiazine 7 and nitroso- benzene, since it had earlier also been demonstrated that a-azoalcohols may be generated by addition of diazenes to aldehydes7�}9 (but not to ketones), and nitrosobenzene may well be regarded as aza-analogous to benzaldehyde.Ketone- derived a-hydroxydiazenes have been reported by Schulz et al.,10 and the proposed fragmentation pattern for 1 is well in accord with the suggested fragmentation of a-hydroperoxy diazenes11 and a-hydroxydiazenes,12 which have been demonstrated as a source of alkyldiazenes. Diimines 7 may either form the ayldiazenyl radicals or lose nitrogen to produce the arenes 6; loss of nitrogen from the aryldiazenyl radical leaves an aryl radical which may dimerise to form the biaryls 5.On the other hand, loss of dinitrogen oxide (N2O) from compound 8 generates phenyl- aminyl and aryl radicals. The latter can dimerise into the biayls 5 or couple with phenylaminyl radical to form the penylarylamines 4. Alternatively, phenylaminyl may react with any aryl to form phenylnitrene and the corresponding arenes 6; dimerisation of the pheylnitrene results in for- mation of azobenzene 3.It should be noted that phenyl- diazene may give dinitrogen and hydrazobenzene in a bimolecular process.13 Moreover, hydrazobenzene could be converted into 3 by dehydrogenation. J. Chem. Research (S), 1998, 406�}407$ Scheme 1 a Ar a Ph; b Ar a p-MeC6H4; c Ar a p-MeOC6H4; d Ar a p-ClC6H4 Scheme 2 a Ar a Ph; b Ar a p-MeC6H4; c Ar a p-MeOC6H4; d Ar a p-ClC6H4 $This is a Short Paper as deRned in the Instructions for Authors, Section 5.0 [see J.Chem. Research (S), 1998, Issue 1]; there is there- fore no corresponding material in J. Chem. Research (M). *To receive any correspondence. 406 J. CHEM. RESEARCH (S), 1998The pyrolysis of triazene 1-oxides 1 in toluene was investi- gated qualitatively. As expected, arylation of toluene to form the three isomers 9±11, as well as formation of benz- aldehyde 12, cresols 13 and nitrosobenzene 14, 1,2-diphenyl- ethene 15 besides 2±6 were observed. The reaction products were identi®ed by GC-MS as in the case of acetonitrile, as solvent.The product pattern was rationalised in the same manner as in the case of acetonitrile, assuming radical pro- cesses throughout. Formation of benzaldehyde 12 and cre- sols 13 in this case may be attributed to toluene acting as a hydrogen source and consequently giving rise to benzyl rad- icals which have to react with some oxygen source (H2O). 1,2-Diphenylethene 15 may be formed by combination of benzyl radicals with 12.These results generally show that diaryltriazene 1-oxides 1 may serve as a source of aryl radicals. One has, however, to accept accompanying formation of arylamino and aryl- hydroxyamino radicals with their own follow-up reactions. Experimental Melting points were taken with a microscope/Reichert Thermovar and Gri�n apparatus and uncorrected. The triazene 1-oxides 1a±d (1a: mp 127 8C, lit., 127 8C. 1b: mp 130±131 8C, lit., 131 8C. 1c: mp 113±114 8C, lit., 114 8C. 1d: mp 146±147 8C, lit., 146 8C)14 were prepared according to the literature.15 Acetonitrile and toluene were puri®ed following Vogel,16 dried and distilled. GC-MS spectra were recorded using a HP5890 series II Gas chomatograph and HP5971 mass-selective detector (Hewlett-Packard) using SE-54 on Chromosorb as a column packing material (polysiloxane with 94% methyl, 1% vinyl, and 5% phenyl). The column length was 25 m, inner diameter 0.25 mm and outer diameter 0.38 mm.General method.�Solutions of 0.5 mmol of each unsymmetrically substituted triazene 1-oxide 1 in 1 ml of the dry reactant solvent (either acetonitrile or toluene) were placed in sealed ampoules and kept for 8 h at 90 8C. Single ampoules were then withdrawn for GC-MS analysis. Available authentic samples were used for the identi®cation and quanti®cation of the products; the other com- pounds were identi®ed by comparison of spectral and physical data with those of reported samples.Received, 27th January 1998; Accepted, 24th March 1998 Paper E/8/00732B References 1 A. M. Nour El-Din, A. A. Hassan, S. K. Mohamed, F. F. Abd- Elatif and H. El-Faham, Bull. Chem. Soc. Jpn., 1992, 65, 553. 2 A. M. Nour El-Din, S. K. Mohamed and D. DoÈ pp, Bull. Chem. Soc. Jpn., 1996, 69, 131. 3 G. T. Morgan and L. P. Walls, J. Chem. Soc., 1930, 1502. 4 R. L. Hadie and R. H. Thomson, J. Chem. Soc., 1958, 1286. 5 T. Mitsuhashi, Y. Osamura and O. Simamura, Tetrahedron Lett., 1965, 2593. 6 A. B. Boese, L. W. Jones and R. T. Major, J. Am. Chem. Soc., 1931, 53, 3530. 7 S. Hu È nig and G. BuÈ ttner, Angew. Chem., 1969, 81, 465. 8 G. Bu È ttner and S. Hu È nig, Chem. Ber., 1971, 104, 1088, 1104. 9 G. Bu È ttner, J. Cramer, L. Geldern and S. HuÈ nig, Chem. Ber., 1971, 104, 1118. 10 M. Schulz, U. Missolrakt. Chem., 1974, 47, 316. 11 M. Schulz and U. Missol, J. Prakt. Chem., 1980, 14, 265. 12 M. Schulz and U. Missol, Z. Chem., 1974, 14, 265. 13 S. Chatterjee, J. Chem. Soc. B,, 1969, 725. 14 T. Mitsuhashi and O. Simamura, J. Chem. Soc. B, 1970, 705. 15 E. Bamberger, Ber. Bunseinges. Phys. Chem., 1896, 29, 102; E. Bamberger and E. Renauld, ibid., 1897, 30, 2278; E. Bamberger and A. Stiegelmann, ibid., 1899, 32, 3554. 16 A. I. Vogel, A Textbook of Practical Organic Chemistry, 3rd edn., Longman, London, 1957. Scheme 3 a Ar à Ph; b Ar à p-MeC6H4; c Ar à p-MeOC6H4; d Ar à p-ClC6H4 Scheme 4 a Ar à Ph; b Ar à p-MeC6H4; c Ar à p-MeOC6H4; d Ar à p-ClC6H4 J. CHEM. RESEARCH (S), 1998 407
ISSN:0308-2342
DOI:10.1039/a800732b
出版商:RSC
年代:1998
数据来源: RSC
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52. |
Base-catalysed Alkylation of 2,7-Naphthalenediol with Glyoxal. Isolation of Structurally Intriguing Products and their Stereochemistry |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 7,
1997,
Page 408-408
Xiaobo Fan,
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摘要:
Base-catalysed Alkylation of 2,7-Naphthalenediol with Glyoxal. Isolation of Structurally Intriguing Products and their Stereochemistry Xiaobo Fan,a Tomoko Yanai,b Makoto Yamaye,c Hirochi Okazakib and Taketoshi Kito*d aShima Tec Co., Ltd., 4-6 Yubaru-machi Yahatanishi-ku, Kitakyushu-shi 807, Japan bShinnikka Environmental Engineering Co., Ltd., Nakabaru, Tobata-ku, Kitakyushu-shi 804, Japan cFaculty of Engineering, Kyushu Kyoritsu University, Jiyugaoka, Yahatanishi-ku, Kitakyushu-shi 807, Japan dDepartment of Chemistry, Kyushu Institute of Technology, Sensui-cho, Tobata-ku, Kitakyushu-shi 804, Japan 1,8-(2,5-Dihydroxy-1,4-dioxane-3,6-diyl)naphthalene-2,7-diol and 1,2,9,10-tetrahydronaphtho[2,1-b:7,8-b']difuran- 1,2,9,10-tetrol are prepared by reaction of 2,7-naphthalenediol with glyoxal, and their stereochemistry investigated mainly by NMR spectroscopy. The base-catalysed alkylation of 2,7-naphthalenediol with glyoxal was carried out in aqueous KOH.Ether extraction of the reaction mixture gave compound 1,2,9,10-tetrahydronaphtho[2,1-b:7,8-b']difuran-1,2,9,10-tetrol (4).Addition of methanesulfonic acid to the aqueous layer, followed by stirring the resultant mixture at 45 8C for 2 h, a€orded 1,8-(2,5-dihydroxy-1,4-dioxane-3,6-diyl)naphthalene- 2,7-diol (3) as a precipitate. The latter product had a 1,4- dioxane ring system Rxed on the 1,8-positions of the naphthalene ring. Under acidic conditions, the tetrol readily reacted with 2-naphthol to form the corresponding furo- furan derivatives or underwent dehydration to a€ord the corresponding dilactone.The stereochemistry of these products was investigated mainly by NMR spectroscopy with the help of MO calculation. A possible pathway for their formation was discussed. An inspection of the molecular model of 3 revealed that three types of stereoisomers are possible in regard to the orientation of the two hydroxy groups on the two hemiacetal carbons (C2 and C5), namely up-up, down-down and up-down isomers.For each of these three isomers, there are a pair of mirror images. The 1H NMR study for 3 showed two groups, each of which is composed of three singlets for the two hydroxy groups on the hemiacetal carbon and the two phenolic hydroxy groups with the proton ratio of 0.74 : 0.74 : 0.52, respectively; indicating that compound 3 may consist of three stereoisomeric structural isomers. Attempted separation of these stereoisomers failed. Consequently, 3 was transformed into its tetraacetate (3ac) for characterization. In the liquid chromatogram of 3ac, there was a small peak with a retention time of 29 s and two large peaks with times of 43 and 48 s.Although the Rrst component (3ac1) could not be isolated due to its low content, the other two compounds (3ac2 and 3ac3) were successfully separated by recrystallization from benzene. The 1H NMR and NOE spectra (in CDCl3) of 3ac2 and 3ac3 were measured. Based on the results of NMR and the MO calculation, the stereo- chemistries of 3ac2 and 3ac3 are up-down and up-up isomers, respectively.The structure of 4, whose structure was reported in a previous paper2 without geometry, consists of six isomers with regard to the orientation of the four hydroxy groups on C1, C2, C9 and C10 atoms, excluding mirror images. According to the discussion of the results for 1H NMR and NOE spectra of 4ac1, 4ac2 and 4ac3, they were assigned to the cis-cis-syn, cis-cis-anti and trans-trans-anti isomers, respectively.In the synthesis of 3 and 4, it was found that their yields di€ered depending on the ether extraction times after the base-catalysed alkylation of 2,7-naphthalene with glyoxal. When the extraction times were 0, 3, 4, 5 and more, the yield of 4 was 0, 18, 27, 44 and 60%, respectively, the corre- sponding yield of 3 was 67, 55, 42, 29 and very little. This results suggest that isomers 3 and 4 can interconvert under base or acid conditions. Techniques used: IR, 1H and 13C NMR, NOE, mass spectroscopy, elemental analysis, DSC References: 10 Table 1: The 1H NMR chemical shifts of isomers of 3ac in CDCl3 Table 2: Heats of formation and dihedral angles of 3ac Table 3: The signals in 1H NMR spectra of 4ac isomers in CDCl3 Fig. 1: Stereoisomers of 3 (R a H) and 3ac (R a COMe) Scheme 1: Reaction of 2,7-dihydroxynaphthalene with glyoxal Received, 2nd February 1998; Accepted, 23rd March 1998 Paper E/8/00878G Reference cited in this synopsis 2 X. Fan, M. Yamaye, Y. Kosugi, H. Okazaki, H. Mizobe, T. Yanai and T. Kito, J. Chem. Soc., Perkin Trans. 2, 1994, 2001. J. Chem. Research (S), 1998, 408 J. Chem. Research (M), 1998, 1538�}1548 Scheme *To receive any correspondence (e-mail: tkito@che.kyutech.ac.jp). 408 J. CHEM. RESEARCH (S), 19
ISSN:0308-2342
DOI:10.1039/a800878g
出版商:RSC
年代:1998
数据来源: RSC
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