The dipole moments of halogen-derivatives of hinokitiol (4-isopropylcyc]oheptatriene-2,4, 6-ol-2-one-1) were measured in benzene solution at 25°. The values obtained are: β-monobromohinokitiol (3-bromo-), 4.40 D; α-monochlorohinokitiol (5-chloro-), 2.70 D; β-monochlorohinokitiol (7-chloro-), 4.38 D; γ-monochlorohinokitiol (3-chloro-), 4.74 D; α-dichlorohinokitiol (3,7-dichloro-), 4.46 D. By analysing the results obtained, the position of substituents in the halogenated hinokitiols were determined and are given immediately after each name of these compounds in parentheses.
The dipole moments of tropolone (cycloheptatriene-2,4,6-ol-2-one-1) and related compounds were measured in benzene solution. The values obtained are:— tropolone, 3.71 D (25°) and 3.64 D (35°) ; tribromotropolone (3,5,7-tribromo-), 1.84D(25°); hinokitiol(4-isopropylcycloheptatriene-2,4,6-ol-2-one-1), 4.04 D (33°); α-monobromohinokitiol (7-bromo-), 4.32 D (33°); α-dibromohinokitiol (3,7-dibromo-), 4.27 D (33°); β-dibromohinokitiol (5,7-dibromo-), 3.14 D (20°); α-mononitrohinokitiol (3- or 7-nitro-), 6.19 D (25°); dinitrohinokitiol (3,5- or 3,7-dinitro-), 4.63 D (20°). The high dipole moments of tropolone and hinokitiol were explained adequately by taking into consideration the contribution of various resonance structures with a formal positive charge at the ring C-atoms. The resonance was supposed to give a certain amount of double bond character to each bond in the ring, causing plane cycloheptatrienolone ring. The position of substituents in the substituted tropolone and hinokitiols were determined and are given immediately after each name of these compounds in parentheses.
Ethyl 2-amino-3-nitrosoazulene-l-carboxylate (II) was synthesized from ethyl 2-aminoazulene-1-carboxylate by treatment with isoamyl nitrite. The structure of the amino-nitrosoazulene was proved by the reductive acetylation of the azulene to give ethyl 2,3-diacetylaminoazulene-l-carboxylate. This nitrosation method was then applied to several azulenes possessing different substituents; it yielded some stable nitrosoazulene derivatives. The spectral properties of the nitrosoazulenes will be discussed. The condensation reactions of II with aromatic amines failed to give azo-dyes, but with diethyl malonate and malononitril they gave the corresponding pyrazinoazulene derivatives.
The first X-ray crystallographic analysis on azulenequinones is reported for 3,5-guaiazulenedione. Two unique azulenone derivatives, 3a-hydroxy-3(3aH)-guaiazulenone and 2,2′-bi-3,5-guaiazulenedione, are obtained by the autoxidation of 5,5′-biguaiazulene-3,3′(5H,5′H)-dione in pyridine at 25 °C. The possible reaction pathways for these azulenone formation are discussed.
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