5,6-二甲基苯並咪唑

5,6-二甲基苯並咪唑
	IUPAC名; 5,6-Dimethyl-1H-benzimidazole
識別
CAS號	582-60-5
PubChem	675
ChemSpider	655
SMILES	CC1=CC2=C(C=C1C)N=CN2;
InChI	1/C9H10N2/c1-6-3-8-9(4-7(6)2)11-5-10-8/h3-5H,1-2H3,(H,10,11);
InChIKey	LJUQGASMPRMWIW-UHFFFAOYAV
Beilstein	116595
Gmelin	279255
EINECS	209-488-1
ChEBI	15890
DrugBank	DB02591
KEGG	C03114
性質
化學式	C9H10N2
摩爾質量	146.19 g·mol−1
外觀	淺黃色固體
密度	1.17 g·cm−3（25 °C）（漂浮法測定）
熔點	201—202 °C（474—475 K）; 205—206 °C（478—479 K）
危險性
	GHS危險性符號;
GHS提示詞	警告
H-術語	H302, H315, H319, H335, H412
P-術語	P261, P264, P270, P271, P273, P280, P301+312, P302+352, P304+340, P305+351+338, P312, P321, P330, P332+313
	若非註明，所有數據均出自標準狀態（25 ℃，100 kPa）下。

5,6-二甲基苯並咪唑是一種天然的苯並咪唑衍生物，它是維生素B12中的鈷的配位分子片段，^[4]也是維生素B12的酸降解產物。^[5]

合成

5,6-二甲基苯並咪唑可由黃素單核苷酸經5,6-二甲基苯並咪唑合成酶（英語：5,6-dimethylbenzimidazole synthase）生物合成。^[6]

它也可以由4,5-二甲基-1,2-苯二胺（維基數據所列：Q27094115）和原甲酸三乙酯在碘（或三氟甲磺酸鎵（維基數據所列：Q72479978）^[3]）催化下於乙腈中反應製得。^[1]

結構

5,6-二甲基苯並咪唑從常壓下的水溶液中結晶，可以得到無水物晶體，無水物的α型和β型均以單斜晶系P2₁/c空間群結晶^[7]，其結構中包含晶體學獨立的5,6-二甲基苯並咪唑單元，它們通過NH⋯N氫鍵連接，每個單元中的所有原子共平面。^[2]它在0.25 GPa以上的壓力下結晶，可以得到半水合物晶體C₉H₁₀N₂·1⁄2H₂O，X射線單晶衍射表明，該晶體以正交晶系Fddd空間群結晶，相比於無水物，半水合物分子中的NH⋯N氫鍵被NH⋯O鍵和OH⋯N鍵取代。^[7]

當它在0.6 GPa以上的甲醇或乙醇溶液結晶時，可以得到P2₁/c空間群的α-C₉H₁₀N₂·CH₃OH或P1空間群的C₉H₁₀N₂·CH₃CH₂OH。其中，α-C₉H₁₀N₂·CH₃OH加壓至1.4 GPa發生相變，得到三斜晶系P1空間群的β-C₉H₁₀N₂·CH₃OH，這些晶體中均存在NH⋯OH⋯N氫鍵。^[8]

反應

5,6-二甲基苯並咪唑和溴化氰在三甲胺存在下反應，可以得到5,6-二甲基苯並咪唑-1-甲腈。^[9]

它和苦味酸在水溶液中反應，可以得到黃色的苦味酸鹽沉澱。^[5]它和高氯酸在水溶液中反應，可以得到相應的高氯酸鹽。^[10]

參考文獻

^ ^1.0 ^1.1 ^1.2 Zhang, Zhan-Hui; Li, Jian-Jiong; Gao, Yuan-Zhe; Liu, Yu-Heng. Synthesis of 2-substituted benzimidazoles by iodine-mediated condensation of orthoesters with 1,2-phenylenediamines. Journal of Heterocyclic Chemistry. 2007, 44 (6): 1509-1512. ISSN 0022-152X. doi:10.1002/jhet.5570440642.
^ ^2.0 ^2.1 YoungJa Lee and W. R. Scheidt. Structure of 5,6-dimethylbenzimidazole. Acta. Cryst. 1986, (C42): 1652-1654.
^ ^3.0 ^3.1 Liu, Juyan; Liu, Qian; Xu, Wei; Wang, Weilu. Expeditious and Efficient Synthesis of Benzoxazoles, Benzothiazoles, Benzimidazoles Catalyzed by Ga(OTf)₃ under Solvent-Free Conditions. Chinese Journal of Chemistry. 2011, 29 (8): 1739-1744. ISSN 1001-604X. doi:10.1002/cjoc.201180310.
^ Barker, HA; Smyth, RD; Weissbach, H; Toohey, JI; Ladd, JN; Volcani, BE. Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5,6-dimethylbenzimidazole. The Journal of Biological Chemistry. 1960, 235 (2): 480–8. PMID 13796809. doi:10.1016/S0021-9258(18)69550-X .
^ ^5.0 ^5.1 Brink, Norman G.; Folkers, Karl. Vitamin B12. X. 5,6-Dimethylbenzimidazole, a degradation product of vitamin B12. Journal of the American Chemical Society. 1950, 72 (4442-4443). ISSN 0002-7863. doi:10.1021/ja01166a027.
^ 5,6-Dimethylbenzimidazole biosynthesis. MetaCyc. 2024-07-12 [2024-07-13].
^ ^7.0 ^7.1 Witold Zieliński and Andrzej Katrusiak. Hydrate smaller than the anhydrate. CrystEngComm. 2015, 17 (29): 5468-5473.
^ Witold Zielinski and Andrzej Katrusiak. Pressure-induced preference for solvation of 5,6-dimethylbenzimidazole. CrystEngComm. 2016, (18): 3211-3215.
^ Kaupp, Gerd; Schmeyers, Jens; Boy, Jurgen. Quantitative Gas–Solid Reactions with ClCN and BrCN: Synthesis of Cyanamides, Cyanates, Thiocyanates, and Their Derivatives. Chemistry - A European Journal. 1998, 4 (12): 2467-2474. ISSN 0947-6539. doi:10.1002/(SICI)1521-3765(19981204)4:12<2467::AID-CHEM2467>3.0.CO;2-D.
^ Bayar, I.; Khedhiri, L.; Soudani, S.; Lefebvre, F.; Ferretti, V.; Ben Nasr, C. Crystal structure, quantum mechanical investigation, IR and NMR spectroscopy of two new organic perchlorates: (C₆H₁₈N₃)·(ClO₄)₃H₂O (1) and (C₉H₁₁N₂)·ClO₄ (2). Journal of Molecular Structure. 2018, 1161: 486-496. ISSN 0022-2860. doi:10.1016/j.molstruc.2018.02.038.

[Zhang-1] 1.0 ^1.1 ^1.2 Zhang, Zhan-Hui; Li, Jian-Jiong; Gao, Yuan-Zhe; Liu, Yu-Heng. Synthesis of 2-substituted benzimidazoles by iodine-mediated condensation of orthoesters with 1,2-phenylenediamines. Journal of Heterocyclic Chemistry. 2007, 44 (6): 1509-1512. ISSN 0022-152X. doi:10.1002/jhet.5570440642.

[Lee-2] 2.0 ^2.1 YoungJa Lee and W. R. Scheidt. Structure of 5,6-dimethylbenzimidazole. Acta. Cryst. 1986, (C42): 1652-1654.

[Liu-3] 3.0 ^3.1 Liu, Juyan; Liu, Qian; Xu, Wei; Wang, Weilu. Expeditious and Efficient Synthesis of Benzoxazoles, Benzothiazoles, Benzimidazoles Catalyzed by Ga(OTf)₃ under Solvent-Free Conditions. Chinese Journal of Chemistry. 2011, 29 (8): 1739-1744. ISSN 1001-604X. doi:10.1002/cjoc.201180310.

[4] Barker, HA; Smyth, RD; Weissbach, H; Toohey, JI; Ladd, JN; Volcani, BE. Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5,6-dimethylbenzimidazole. The Journal of Biological Chemistry. 1960, 235 (2): 480–8. PMID 13796809. doi:10.1016/S0021-9258(18)69550-X .

[Brink-5] 5.0 ^5.1 Brink, Norman G.; Folkers, Karl. Vitamin B12. X. 5,6-Dimethylbenzimidazole, a degradation product of vitamin B12. Journal of the American Chemical Society. 1950, 72 (4442-4443). ISSN 0002-7863. doi:10.1021/ja01166a027.

[6] 5,6-Dimethylbenzimidazole biosynthesis. MetaCyc. 2024-07-12 [2024-07-13].

[Witold-7] 7.0 ^7.1 Witold Zieliński and Andrzej Katrusiak. Hydrate smaller than the anhydrate. CrystEngComm. 2015, 17 (29): 5468-5473.

[8] Witold Zielinski and Andrzej Katrusiak. Pressure-induced preference for solvation of 5,6-dimethylbenzimidazole. CrystEngComm. 2016, (18): 3211-3215.

[9] Kaupp, Gerd; Schmeyers, Jens; Boy, Jurgen. Quantitative Gas–Solid Reactions with ClCN and BrCN: Synthesis of Cyanamides, Cyanates, Thiocyanates, and Their Derivatives. Chemistry - A European Journal. 1998, 4 (12): 2467-2474. ISSN 0947-6539. doi:10.1002/(SICI)1521-3765(19981204)4:12<2467::AID-CHEM2467>3.0.CO;2-D.

[10] Bayar, I.; Khedhiri, L.; Soudani, S.; Lefebvre, F.; Ferretti, V.; Ben Nasr, C. Crystal structure, quantum mechanical investigation, IR and NMR spectroscopy of two new organic perchlorates: (C₆H₁₈N₃)·(ClO₄)₃H₂O (1) and (C₉H₁₁N₂)·ClO₄ (2). Journal of Molecular Structure. 2018, 1161: 486-496. ISSN 0022-2860. doi:10.1016/j.molstruc.2018.02.038.

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