Hexamethoxy

When the aldehyde is heated on the water-bath with 25 per cent, hydrochloric acid, it yields a triphenylmethane derivative, nonamethoxy-triphenylmethane, a body consisting of snow-white crystals, melting at 184 5°. The action of concentrated nitric acid upon the solution in glacial acetic acid of this triphenylmethane derivative gives rise to 1, 2, 5-trimethoxy-4-nitrobenzene (melting at 130°). With bromine, nonamethoxytriphenylmethane combines, with separation of a molecule of trimethoxy bromobenzene, into a tribromo additive compound of hexamethoxy diphenylmethane, a deep violet-blue body. The 1, 2, 5-tri-methoxy-4-bromobenzene (melting at 54 5°) may be obtained more readily from asaronic acid. 

It was Breslow (Breslow, 1982 Breslow et ai., 1982) who first paid attention to this theory. Knowing that the pentachlorocyclopentadienyl cation (Breslow et ai, 1964 Saunders et ai, 1973), the hexachlorobenzene dication (Wasserman et al., 1974) and the 2,3,6,7,10,11-hexamethoxy-triphenylene (HMT, [36]) dication are all ground-state triplets, in good agreement with theory, Breslow and coworkers set out on the synthesis of analogues that should have lower oxidation potentials, be chemically more stable and therefore form CT complexes more readily (Fig. 21c Breslow et al., 1982, 1984 Breslow, 1985, 1989 LePage and Breslow, 1987). 

S,5S)-2-(6 -terl-butyldimethy silyloxy-2. 3, 4,4 , 5,6-hexamethoxy-l, l -biphenyl-2-yl)-4,5-dihydro-4-methoxymethyl-5-phenyloxazole... 

Neben den bereits beschriebenen Difluor-azoxybenzolen (Bd.X/3, S.761) konnte auch 5-Nitro-l,2,3-trimethoxy-benzol in guten Ausbeuten zum 3,3, 4,4, 5,5 -Hexamethoxy-az-oxybenzol umgesetzt werden. Mit Zink und Calciumchlorid in waBrigem Methanol betragt die Ausbeute 82% mit Zink, Ammoniumchlorid und Salpetersaure entsteht ein Komplex aus dimerem 5-Nitroso-l,2,3-trimethoxy-benzol mit Zinkchlorid1. 

It was shown that a Dgh symmetric structure for 150 required a 1.88 A long Si—F bond, and was not possible due to the substantially shorter Si—F bonds (1.68 A). For this purpose the hexamethoxy analog (151) was prepared and studied, and indeed, with the longer (1.88 A) Si—O bonds, a perfect D6h structure was obtained in a single crystal study177. 

Figure 1.12. Comparison of the transient infrared spectra on the microsecond time scale of hypericin, O-hexamethoxy hypericin, and a hypericin analog that lacks carbonyl groups (the hexaacetoxy analog). The salient feature of the data is that the latter two compounds, which cannot execute excited state H-atom transfer owing to the absence of either labile protons or appropriate carbonyl groups, lack the feature at 1450 cm-1. Ab initio calculations at the Hartree-Fock 3-21G level for the normal and two monotautomeric forms of the hypericin triplets indicate normal modes with substantial character in the region 1400-1460 cm-1 [77]. While these preliminary results do not demonstrate a time-resolved H-atom transfer, they do clearly point to a region of the spectrum that must be investigated in further studies. Hypericin and hexamethoxy hypericin, solid line, 0-1 p,s and dashed line, 14-18 ps reduced analog, solid line, 0-0.5 ps, and dashed line, 7-9 ps.

Hexamethoxy tellurium was prepared by the addition of orthotelluric acid to a solution of diazomethane in diethyl ether1,2. 

Hexamethoxy tellurium dissolves in anhydrous hydrogen methoxy tellurium fluorides2. 

Pentaalkoxy tellurium monofluorides were formed by fluorination of tctramethoxy tellurium1, by reaction of m-tetramethoxy tellurium difluoride with sodium methoxide in methanol1, by the action of anhydrous hydrogen fluoride on hexamethoxy tellurium2, and by the condensation of primary alcohols with tellurium hexafluoride1. None of these compounds was isolated. Their presence in the reaction mixture was detected by 19F-NMR spectroscopy. 

Tetramethoxy tellurium difluoride was observed by 19F-NMR spectroscopy as one of the products of the interaction of hexamethoxy tellurium in anhydrous hydrogen fluoride at 60° for 24 h2. 

Hexamethoxy tellurium dissolved readily in anhydrous hydrogen fluoride. After heating the mixture at 60° for 24 hours, the reaction appeared to have been complete. All possible methoxy tellurium fluorides, among ihem jac-trimethoxy tellurium trifluoride, were present in the mixture. The components of the mixture were not separated but identified by 10F-NMR spectroscopy2. 

Hexamethoxy tellurium dissolved in anhydrous hydrogen fluoride had formed, after 24 hours at 60° some methoxy tellurium pentafluoride and all the other possible methoxy... 

Tetramethoxy tellurium and hexamethoxy tellurium reacted with 2,2-dilithiobiphenyI to give bis[2,2 -biphenyldiyl] tellurium3 1. A trisp -biphenyldiyl] tellurium was not detected. 

Hexamethoxy Tellurium A solution of freshly prepared diazomethane in dry diethyl ether is cooled to 0°, finely powdered orthotelluric acid is added to the solution, and the mixture is allowed to warm to 0°. The mixture is kept at 20° for 24 h and then filtered to remove unreacted orthotelluric acid. The diethyl ether is evaporated under moisture-free conditions. The residue is recrystallized from absolute diethyl ether or, alternatively, sublimed. The white crystalline product has an irritating odor m.p. 77°. 

Hexamethoxy tellurium dissolves in anhydrous hydrogen fluoride and reacts to form methoxy tellurium fluorides. ... 

When hexamethoxy tellurium was dissolved in anhydrous hydrogen fluoride, cis-dimetkoxy tellurium tetrafluoride was observed by F-NMR spectroscopy as one of the products ... 

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