Ethers biphenyl

Biphenyl ether bis (2-Chloromethyl) ether bis (Dimethylaminoethyl) ether Bromine... 

In contrast to the Gomberg-Bachmann reaction, the intramolecular variant, the Pschorr reaction, is carried out in strongly acidic solution, and in the presence of copper powder. Diazonium biphenyl ethers are converted to dibenzofurans, e.g. 8 9 ... 

Dowtherm (biphenyl + biphenyl ether) and its impurities (phenol, dibcnzofuran, benzophcnone, terphenyl, phenoxybiphcnyl. xanthone, and diphenoxybenzene)... 

In Figure 13.2, the intensity of the ion at m/z 170 represents a molecular ion of an aromatic compound. The characteristic losses from the molecular ion (M - 1, M - 28, and M - 29) suggest an aromatic aldehyde, phenol, or aryl ether. The molecular formula of Ci2H 0O is suggested by the molecular ion at m/z 170, which can be either a biphenyl ether or a phenylphenol. The simplest test to confirm the structure is to prepare a TMS derivative, even though m/z 11 strongly indicates the diaryl ether. 

This reaction has been also described for low chlorinated dibenzodioxins. Assuming an identical MS response factor for monoBrDD and monobromohydroxy-biphenyl ether (monoBrDPE) a quantification study shows that monoBrDPE is much more stable towards photolysis compared to monoBrDD, because it accumulates in the mixture of the reaction products. For the dibrominated dibenzodioxins the same reaction (ether fission) is observed but to a minor extent. With triBrDD and higher brominated BrDD no diaryl-ether products are observed at all. 

The oxidation of triclosan was initiated by oxidation to the PhO radical. In analogy with reactions established in biomimetic synthesis, this nnderwent coupling to produce biphenyl ethers and biphenyls that were oxidized further to diphenoquinones (Zhang and Huang 2003). 

Organobrominated substances Polybrominated biphenyl ethers Bromophenols Dioxin-like compounds Tetrabromobisphenol A... 

Janetka and Rich (78) have utilized the considerable stability of ruthenium-77-arene systems in the synthesis of cyclic tripeptides as analogs of the protease inhibitor K-13 (cf. 34, Scheme 28). Their approach involves the construction of linear tripeptide complexes (35) using diimide/HOBt coupling of [Ru(Cp)(Boc-p-Cl-PheOH)]PF6 (Cp = 775-C5H5) with the appropriate dipeptide ester. Cyclization of 35 affords the biphenyl ether 36, which on photolysis (350 nm) gives 34. 

Synonyms AI3-00749 Biphenyl ether Biphenyl oxide BRN 1364620 CCRIS 5912 Diphenyl ether Diphenyl oxide EINECS 202-981-2 FEMA No. 3667 Geranium crystals NSC 19311 NSC 174083 1,1-Oxybisbenzene Phenoxybenzene Phenyl oxide UN 3077. 

Polychlorinated biphenyls (PCB) Polybrominated biphenyls Polybrominated biphenyl ethers Flame retardants... 

In 1994, a Rayox system consisting of nine 30-kW reactors was installed at a polyester plant in Salisbury, North Carolina. The system treated groundwater contaminated with 1,4-dioxane and biphenyl ether. The operating cost for the system was 0.76 per 1000 gal of water treated (D135159). 

Polybrominated Biphenyl Ethers. The widespread use of PBDEs over the past 30 years has resulted in their ubiquitous presence in 1he environment. PBDEs are released into the environment from their manufacture and use as additive flame retardants in thermoplastics in a wide range of products (WHO 1994a). PBDEs containing waste may be either incinerated as municipal waste, deposited in landfills. 

Loganathan BG, Kannn K, Watanabe, et al. 1995. Isomer-specific determination and toxic evaluation of polychlrinated biphenyls, polychlorinated/brominated dibenzo-p-dioxins and dibenzofurans, polybrominated biphenyl ethers, and extractable organic halogen in carp from the Buffalo River, New York. Environ Sci Technol 29(7) 1832-1838. 

Watanabe I, Kashimoto T, Tatsukawa R. 1987. Polybrominated biphenyl ethers in marine fish, shellfish and river and marine sediments in Japan. Chemosphere 16( 10-12) 2389-2396. 

Heteroanalogs of biphenyl ethers have also been prepared by Alsaidi et al.,22A using PTC. Several other agrichemicals have been obtained from... 

For chemicals with half-lives of months or years—such as dioxins, polychlorinated biphenyls (PCBs), polybrominated biphenyl ethers, and first-generation halogenated insecticides—biomarkers can detect exposures months or even years after they have occurred. Such lipophilic chemicals are usually measured in blood, and the principal exposure source is usually diet. After ingestion, they are readily absorbed into the blood supply blood concentration then decreases rapidly as the blood supply equilibrates with... 

Given these requirements, it is obvious that the P-tetralin based N- and C-caps could not be used as position-independent templates. While the P-tetralin amino acid and the dipeptide units are compatible with a position-independent template design, the biphenyl ether linker unit clearly was not. In N- and C-caps, the linker unit forms a side chain (P-tetralin) to backbone constraint (either to the C-terminal carboxylate or the N-terminal amine), and only one attachment site for a peptide... 

Dysidea herbacea, which sequesters brominated biphenyl ethers synthesized by symbiotic bacteria, concentrates these secondary metabolites in their ectosomal area.89... 

The Lythraceae alkaloids have four centers of chirality—three chiral carbon atoms at the quinolizidine ring C-l, C-3, and C-5, and the dissy-metric biphenyl or biphenyl ether link. The chirality of the biphenyl system in all alkaloids of the group is the same. The chirality of the biphenyl ether link is also the same for all alkaloids in this class (22, 23, 32). 

The NMR spectra of /V-oxides of biphenyl lactonic alkaloids (O-methyl and O-acetyl derivatives) show the signal of low-field aromatic proton H-24 at 5 8.1 -8.7 ppm. The Dreiding models indicate that this proton is deshielded by the N—O group. H-24 resonates in the cis-fused derivatives at 0.13-0.28 ppm lower field than in the corresponding trans forms (24). The same relation is observed in the NMR spectra of biphenyl ether alkaloids where H-24 absorbs at 5 7.6-8.2 ppm (25, 36). 

Hydrolysis of the lactone ring in dimethyldecodine (14) was carried out by prolonged refluxing of the alkaloid in aqueous methanolic sodium hydroxide (17). Ferris reported that the starting material could be recovered in 18% yield using thionyl chloride in chloroform. However, in the total synthesis of the biphenyl ether alkaloid decaline, the yield of lactonization of the corresponding hydroxyacid did not exceed 5% (39, 40). This reaction was usually carried out in much better yield in benzene with p-toluenesulfonic acid (39). 

An X-ray study of vertaline hydrobromide established the structure and absolute stereochemistry of vertaline as shown in 51 (32, 43). The relative stereochemistry at C-l and C-3 in all alkaloids in the group is the same as in the biphenyl alkaloids for example, the biphenyl ether and lactone group are linked to the quinolizidine ring in axial and equatorial configurations, respectively. 

Decaline and vertaline were not degraded under the conditions wherein methiodides were cleaved. Consequently, the cleavage of the C,—N bond must trigger the scission of the biphenyl ether and ester bonds. A mechanism proposed by Ferris et al. (36) is shown for the case of decaline methiodide. 

Lagerine was isolated by Ferris et al. from Lagerstroemia indica (17), and methyllagerine was isolated by Hanaoka et al. (42) from L. indica grown in Japan. The structure of lagerine is unique since it was not possible to convert this base to any known Lythraceae alkaloid. The basic skeletons of O-methyllagerine and vertaline are the same since the mass spectra of the two alkaloids are almost identical. The alkaloids differ in the substitution pattern on the biphenyl ether chromophore, a fact which is reflected in the UV spectra. 

In the third approach (39, 40, 72) the quinolizidone ester was alternatively prepared. The Ullmann reaction of 6-bromoveratraldehyde with methyl 4-hydroxycinnamate afforded biphenyl ether aldehyde (164) in 55% yield. The alkaline condensation of 164 with pelletierine gave a mixture of stereo-isomeric quinolizidone acids (158 and 159). Esterification with dimethyl sulfate yielded a mixture of trans- and cis-fused quinolizidine esters (160 and 161) in a 13 1 ratio after separation on silica gel. 

Several biogenetic schemes have been suggested to account for the origin of biphenyl and biphenyl ether lactonic alkaloids (52, 62, 83, 84). The proposals differ in the mode of biogenesis of the phenylquinolizidine moiety. Steps common to all the proposals are the reduction of oxo group in the phenylquinolizidone (130) followed by esterification with of / -coumaric acid (C6 C3) unit derived from phenylalanine via cinnamic acid. 

The decomposition of 2,2,-bis(azidomethyl)biphenyl in boiling biphenyl ether gives a mixture of phenanthridine and 5/7-dibenz[c,e]-azepine (46). Hydrazoic acid is evolved and the following mechanism has been proposed (Scheme 2) (although attempts to confirm carbene formation were not successful).93... 

PBBs were substituted with safer polybromo diphenyl (or biphenyl) ethers (or oxides) (PBDPEs or PBBPEs or PBDPO or PBBPOs) (Figure 4.7) this time after a very thorough toxicity... 

Chlorinated Paraffins Decabromo-biphenyl ether (Saytex S-102 GLCC DE-83 DSB FR-1210)... 

Kelley, W., Matzner, M., and Patel, S. 1991. Poly(biphenyl ether sulfone) compounds. WO 9115,539. 

The continuing interest in the synthesis of macrocylic alkaloids has been directed this year to the preparation of the cw-quinolizidine group. It is apparent from the work of Hanaoka et al.29 that alkaline conditions for the Mannich condensation of isopelletierine (41) with aryl aldehydes, cf. (39), favour the formation of cis-quinolizidinones. The synthesis of the biphenyl ether alkaloid vertaline (48) was carried out in this way (Vol. 5), and has now been described in full.30... 

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