Octa preparation

COT is prepared by the polymerization of ethyne at moderate temperature and pressure in the presence of nickel salts. The molecule is non-planar and behaves as a typical cyclic olefin, having no aromatic properties. It may be catalytically hydrogenated to cyclo-octene, but with Zn and dil. sulphuric acid gives 1,3,6-cyclooclairiene. It reacts with maleic anhydride to give an adduct, m.p. 166 C, derived from the isomeric structure bicyclo-4,2,0-octa-2,4,7-triene(I) ... 

The three fluorides CIF5, Brp5 and IF5 are the only known hexa-atomic interhalogens, and IF7 is the sole representative of the octa-atomic class. The first to be made (1871) was IF5 which is the most readily formed of the iodine fluorides, whereas the more vigorous conditions required for the others delayed the synthesis of BrFs and IF7 until 1930/1 and CIF5 until 1962. The preferred method of preparing all four compounds on a large scale is by direct fluorination of the element or a lower fluoride ... 

Palladous chloride in preparation of hydrogenation catalyst, 46, 89 Paraformaldehyde, conversion to form aldoximc, 46,13 Pelargonyl fluoride 46, 6 1-Pentalenecaeboxylic acid, octa hydro-, 47,10... 

When 2,7-dimethyloxepin is treated with potassium in liquid ammonia at — 70 C, a mixture of oct-4-en-2-one (1) and octa-4,6-dien-2-one (2) in a ratio of 75 20 is obtained.203 The major product can be separated by preparative gas chromatography in 23% yield. The analogous reaction of 3-benzoxepin gives, in 30% yield, a mixture of (2-cthylphenyl)acetaldehyde (3) and (2-ethynylphenyl)acetaldehyde (4) that resists separation.203 The Latter product can be formed exclusively in 17% yield when 3-benzoxepin is treated with sodium amide in tetra-hydrofuran at 33 C for 210 minutes.203... 

Analogously, the corresponding octa(phcnylsulfanyl)- (16 %), octa(phenylseianyl)- (51 %) and octa(phenyltellanyl)-substituted (35%) copper(II) 2,3-naphthalocyanines can be prepared. 

If lanthanide salts (e.g., Yb(OAc)3 H20) are used as the metal compound, hexadecasub-stituted bis(phthalocyanines) can be prepared starting from 2,3,9,10,16.17,23,24-octa-substituted metal-free phthalocyanines.201... 

It had been observed that Octa is predominantly heptabromo DPF (ref. 3). The predominant peak (Fig. IB, peak 4) is here identified as the isomer 2,2, 3,4,4, 5, 6 heptabromo DPF by interpreting the NMR spectrum (Table 1) of material isolated preparatively. 

Of the five remaining peaks (Figure IB, peaks 5 to 9), three (peaks 5,7 and 9), were easily separated from the octa samples by preparative HPLC, and the two remaining (peaks 6 and 8) were isolated from high-melting (Figure 1C). 

The most convenient and successful synthetic preparation of octa-chlorodibenzo-p-dioxin has been described by Kulka (13). The procedure involves chlorination of pentachlorophenol in refluxing trichlorobenzene to give octachlorodibenzo-p-dioxin in 80% yield. Kulka has explained the reaction as coupling between two pentachlorophenoxy radicals. Large amounts (5—15%) of heptachlorodibenzo-p-dioxin were observed in the unpurified product. Since the pentachlorophenol used in this study contained 0.07% tetrachlorophenol, we feel that tetrachloro-phenol may be produced in situ (Reaction 4). Such a scheme would be analogous to the formation of 2,4-dichlorophenol and 3-chlorophenol produced from 2,4,4 -trichloro-2 -hydroxydiphenyl ether (Reaction 2). The solubility of octachlorodibenzo-p-dioxin was determined in various solvents data are presented in Table II. 

With sp bond angles calculated to be around 162°, macrocycle 131 would be highly strained and was therefore expected to be quite reactive [79]. The octa-cobalt complex 132, on the other hand, should be readily isolable. Indeed, 132 was prepared easily from 133 in five steps, and was isolated as stable, deep maroon crystals (Scheme 30). All spectroscopic data supported formation of the strain-free dimeric structure. Unfortunately, all attempts to liberate 132 from the cobalt units led only to insoluble materials. Diederich et al. observed similar problems when trying to prepare the cyclocarbons [5c]. Whether the failure to prepare these two classes of macrocycles is due to the extreme reactivity of the distorted polyyne moiety or to the lack of a viable synthetic route is not certain. Thus, isolation and characterization of smaller bent hexatriyne- and octatetrayne-containing systems is an important goal that should help answer these questions. 

Arylgold(I) compounds can be similarly prepared to alkyl derivatives via the organolithium or the Gridnard route. These methods have been used to prepare pentachlorophenyl,1641 4,4 -octa-fluorobiphenyl (Equation (27)),2109 2,4,6-tris(trifluoromethyl)phenyl,1 2,21 0 triphenylar-... 

Part LXIV. The Preparation of Conjugated Octa- and Deca-acetylenic Compounds. J. Chem. Soc. [London] 1960, 3483-... 

Table 1. Preparation and Anionic Polymerization of Masked Disilene, 1-Phenyl-7,8-disila-bicyclo[2.2.2]octa-2,5-diene...

Complexes 68 (mp 173 °C) and 69 (mp 114°C) were prepared starting from the reaction between trimethallyl-borane and octa-l,7-diyne (Scheme 27) . 

The photophysical properties of magnesium(II) tetra-(i-butyl)phthalocyanine (27) have been studied in solution, in micelles and in liposomes cation radical formation (CBr4 as electron acceptor) has been detected with UV excitation, or by a two-photon excitation using a pulsed laser in the therapeutic window at 670 nm.118 The Mg11 complex of octa(tri-z -propylsilylethy-nyl)tetra[6,7]quinoxalinoporphyrazine (28) has been prepared as a potential PDT sensitizer. The synthesis is shown in Figure 8. Compound (28) has Amax 770 nm (e = 512,000 M-1 cm-1), d>f = 0.46 and d>A = 0.19 (all in THF, under air).119... 

Octa-O-methylsucrose has been prepared by treating sucrose with either dimethyl sulfate-sodium hydroxide, or sodium hydride and methyl iodide in A/,A/-dimethylformamide.35... 

For comparison, it seemed extremely interesting to prepare octa-methyltetrastanna[2.2]paracyclophane (19). However, the attempted reductive coupling of l,4-bis(chlorodimethylstannyl)benzene did not... 

Star-like PFs 236 with a silsesquioxane core have been prepared by Ni-mediated copolymerization of 2,7-dibromo-9,9-dioctylfluorene with octa(2-(4-bromophenyl)ethyl)octasilses-quioxane [333]. The polymer is thermally stable up to 424°C (TGA). In both chloroform solution and films, its absorption and PL spectra are very close to that for PFO 196, although a somewhat higher PL efficiency is observed in films (64 and 55%, respectively). The polymer 236, however, demonstrates a better PL color stability during thermal annealing. An ITO/PEDOT/236/Ca/Ag device can be turned on at 6.0 V, and shows a brightness of 5430 cd/m2 (at 8.8 V) with F] =0.44%, almost twice as high as that for the corresponding PFO device (Chart 2.60). 

PDMS nanocomposites with layered mica-type silicates were also reported.374 A two-step sol-gel process of the in situ precipitation of silica led to the development of siloxane-based nanocomposites with particularly high transparencies.3 5 Some unusual nanocomposites prepared by threading polymer chains through zeolites, mesoporous silica, or silica nanotubes were reviewed.3 6 Poly(4-vinylpyridine) nanocross-linked by octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane was reported.377... 

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