Hexa ether

Research on liquid crystals with a disc-like shape started in 1977 [130] when hexa(hep-tanoyl)benzene (38, first synthesized forty years earlier [131]) was proved to form a columnar mesophase (m.p.=/tj, 81.2°C, cl.p.=/ci 87.0°C) [132]. Disc-shaped amphiphilic molecules with saturated cores, such as the hexaesters 39 or even the hexa-ethers 40 of the naturally occurring scyllo-inositol [9, 109, 133-137] form columnar liquid crystals much more easily with me-sophases more stable and very much wider in range than known for the mentioned benzene derivatives. 

Fig. 25. Conformation of the free hexa-ether [18]ci own-6. Note the elliptical shape of the molecule...

X 10 J/T (5.71 //g) at room temperature. It is air stable at 25°C, but is slowly converted to Fe202 and bromine at 310°C. The light yellow to brown hydroscopic sohd is soluble ia water, alcohol, ether, and acetonitrile. Iron(II) bromide forms adducts with a wide range of donor molecules. Pale green nona-, hexa-, tetra-, and dihydrate species can be crystallized from aqueous solutions at different temperatures. A hydrate of variable water content,... 

Starting compounds include hexa- and pentarylethanes the latter require higher temperatures (ca 100°C) than the former to break the carbon—carbon bond. In the presence of oxygen, stable radicals that are generated by other methods, eg, reduction of arylmethyl ethers and haUdes, also have been converted to diaralkyl peroxides (66). 

Chaput, Jeminet and Juillard measured the association constants of several simple polyethylene glycols with Na", K", Cs", and Tl". Phase transfer catalytic processes and most biological processes are more likely to involve the first two cations rather than the latter two, so we will confine the discussion to these. Stability constants for the dimethyl ethers of tetra-, penta-, hexa-, and heptaethylene glycols were determined poten-tiometrically in anhydrous methanol solution and are shown in Table 7.1. In the third column of the table, the ratio of binding constants (Ks/K s) is calculated. Note that Simon and his coworkers have referred to this ratio as the selectivity constant. ... 

Bocchi et al. [5] pointed out that while the tetraacetate of p-/ T/-butyl calix[4]arene fails to form complexes with guanidium ions or Cs, the octa-(3,6-dioxaheptyl)-ether of p-/cr/-butyl calix[8]arene forms strong complexes with these cations. The Parma group [6] later showed that the hexa-(3-oxabutyl)ether of p-tert-hu y calix[6]arene also forms complexes with these ions. 

A crystalline 5,5 -diene, or bis (vinyl ether), derivative of sucrose has been prepared from 6,6 -dideoxy- 6,6 -diiodo-sucrose hexa-acetate, derived from the 6,6 -ditosylate, by treatment with silver fluoride in pyridine (26). 

Hexa-fluorobisphenol A (HFBPA) based polysulfone and poly(arylene ether phosphine oxide) were prepared by nucleophilic aromatic substitution similar to that of bisphenol-A-based polysulfone and poly(arylene ether phosphine oxide).11... 

Bistline et al. [59] determined the stability to hydrolysis of sodium hexa-decanol, hexadecanol ether (2 EO), octadecanol ether (2 EO), and octadecanol... 

The mixture of deca-BDE is composed almost exclusively of deca-BDE (BDE-209), with a rate of 97% or more and by 3% or less of nonabromodiphenyl ethers (nona-BDEs) and octa-BDEs. On the contrary, the commercial octa-BDE mixture usually contains between 10% and 12% hexabromodiphenyl ethers (hexa-BDEs), 44% of heptabromodiphenyl ethers (hepta-BDEs), between 31% and 35% of octa-BDEs, between 10% and 11% of nona-BDEs and <1% of deca-BDE [4]. The two compounds with a higher proportion in this mixture are, in first place, BDE-183 (2,2, 3,4,4, 5, 6-hepta-BDE) and then the BDE-153 (2,2, 4,4, 5,5 -hexa-BDE). In addition, the penta-BDE mixture, commercially known as DE-71, is primarily composed by tetrabromodiphenyl ethers (tetra-BDEs) (24—38%), penta-BDEs (50-60%) and hexa-BDEs (4-8%) being BDE-99 (2,2, 4,4, 5-penta-BDE) and BDE-47 (2,2, 4,4 -tetra-BDE) the main compounds of the mixture. Figure 1 shows different structures belonging to the three PBDE mixtures described. 

Solvents and reagents are dried in the following fashion Benzene and ether are freshly distilled from sodium methyl iodide is distilled over calcium chloride and potassium hexa-chloroplatinate(IV) is dried at 110°. 

Hex- and hept-2-en-4-yn-l-ol gave hexa-3,4-dienol and hepta-3,4-dienol, respectively. The absolute configuration of ( + )-hexa-3,4-dienol was determined to be S by thermal conversion of (- )-(S)-a-chloroethyl l-methylprop-2-ynyl ether (18) to an allenic aldehyde 19, which was reduced with LAH to (+ )-hexa-3,4-dienol (17, R = Me). (See Scheme 2.)... 

It is noteworthy that similar products are also obtained from oxidation of enol silyl ethers with two equivalents of tris(p-bromo-phenyl)aminium hexa-chloroantimonate which is known to oxidize electron-rich double bonds to... 

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