The structure of p-azoxyanisole

Carlisle, C. H.; Smith, C. H.

doi:10.1107/s0567740871003480

Cited by 14 publications

(1 citation statement)

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“…Optical examination of the phases led them to the conclusion that the nematic phase was structurally related to the metastable rather than the stable crystalline form. The detailed crystal structure of the stable form (III) was determined by Krigbaum, Chatani and Barber in 1970, Carliste and Smith in 1971 and Chebli and Brisse in 1995 . The crystal structure of the metastable polymorph (I) has only been reported recently and this is an important factor in enabling further understanding of nucleation in this system .…”

Section: Introductionmentioning

confidence: 99%

Probing Crystal Nucleation from Fluid Phases: The Nucleation of para-Azoxyanisole from Its Nematic Liquid Crystalline State

2008

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Detailed understanding of structural evolution during the process of crystal nucleation is limited. In this contribution nucleation from the single component nematic phase of para-azoxyanisole is studied with particular emphasis on the structural relationships between liquid crystalline and crystalline phases in this polymorphic system. The data are interpreted and discussed in terms of their relevance to processes occurring within a nucleating cluster. It is clear that while positional order in the supersaturated phase does dictate the structural outcome of crystallization, an activation barrier still exists limiting the overall kinetics of the nucleation process.

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Section: Introductionmentioning

confidence: 99%

Probing Crystal Nucleation from Fluid Phases: The Nucleation of para-Azoxyanisole from Its Nematic Liquid Crystalline State

2008

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Crystallographic investigation of single crystals of the mesogen compound 4′‐nitrophenyl‐4‐n‐octyloxybenzoate

Lemke

1979

Cryst Res and Technol

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X-ray investigations of single crystals of 4'-nitrophenyl-4-n-octyloxybenzoate (NPOB) have been performed for the determination of the space group P2,/c and the lattice constants B = 128.0 f 0.5'). Furthermore powder patterns after Debye-Schemer method have been taken to estimate the d-values together with the indexing. On the baais of small Miller indices the rrystal angles yielded a discrepancy between axis ratios determined from optical measurements and X-ray methods. It can be shown that these differences appear with many molecular crystals.

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1, 4, 5, 6‐Tetrahydro‐ν‐tetrazin‐Derivate

Seebàch

Dach

Enders

et al. 1978

Helvetica Chimica Acta

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1, 4, 5, 6‐Tetrahydro‐ν‐tetrazin‐Derivate The title compounds 2 and 13 are readily available from α‐lithiated N‐alkyl‐nitrosoamines 1 (see Tables 1 and 2) which decompose at − 73° to yield the N‐oxides 2. The ESR. spectra of two derivatives 1 are recorded (Fig. 1), and tentative mechanisms are proposed for the head to head dimerizations (la‐ 3‐ 4‐ 5‐ 2a and Scheme 1). Coupling of lithionitrosoamines with iodine (‐6) and alternative decomposition routes of representatives of this class of organometallics with special substitution [equations (2)‐(5)] are reported. The structures of the tetrazines are established by spectroscopic data [ESCA] (Fig. 2), IR., UV., 1H‐ (cf. Fig. 9) and 13C‐NMR., PE. (Scheme 2), by an X‐ray analysis of 2a (Fig. 4‐8 and Table 3), and by the chemical reactions. The crystal structure of 2a is a twisted boat with non planar terminal nitrogen atoms which reflects the electron repulsion in the 4‐atom‐6‐electron NNNN‐system. Comparisons are made with 2‐tetrazenes, the open chain analogues of 13, wherever possible. Raney‐Ni reductions of 2 or 13 gives diamines 14 to which is assigned the d, l‐configuration through the 1H‐NMR. spectra of the aminals 7 and 15. Neither the oxides 2 nor the tetrazines 13 undergo cycloaddition reactions [equation (6) and Section 4]. Compound 2a is dimerized to the bis (nitrosoamino)‐2‐tetrazene 18 by treatment with acid, ZnII, CuI or iodomethane. 2a is oxidized at nitrogen to the ethylene diamine derivative 6a (through 20, with H2O2), or at the CH2‐groups of the ring to give oxo‐N‐oxide 21 (with MnO2 or the ring contracted oxo‐tetrazoline‐N‐oxide 22 (with KMnO4). Pyrolysis or photolysis of the dimethyl tetrahydrotetrazine 13a furnishes the trimer 26 of N‐methylimine, but no diazetidine 27. Silver and mercury complexes 29 are obtained from 13a, while Cr(CO)5. THF does not furnish a complex as with azocompounds, but rather replaces N2 in 13a by CO (→ 28). Oxidation with permanganate converts 13a into the oxalic acid derivative 30 with unchanged tetrazine structure.

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The structure of p-azoxyanisole

Cited by 14 publications

References 1 publication

Probing Crystal Nucleation from Fluid Phases: The Nucleation of para-Azoxyanisole from Its Nematic Liquid Crystalline State

Probing Crystal Nucleation from Fluid Phases: The Nucleation of para-Azoxyanisole from Its Nematic Liquid Crystalline State

Crystallographic investigation of single crystals of the mesogen compound 4′‐nitrophenyl‐4‐n‐octyloxybenzoate

1, 4, 5, 6‐Tetrahydro‐ν‐tetrazin‐Derivate

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