Oxidation tribromide

Vanadium oxide tribromide, VOBr3. Dark red deliquescent liquid formed by heating V2O3 plus Brj. 

Niobium Oxide Tribromide. Niobium oxide tribromide, NbOBr, is a yeUowbrown soHd which is readily hydrolyzed by moist air. It is prepared by reaction of bromine with a mixture of niobium pentoxide and carbon at 550°C. It decomposes in vacuum to the pentabromide and pentoxide at 320°C. 

In /r-bridged dimers, two phthalocyanine moieties are linked by one or more bridging atoms such as oxygen or halogens. Niobium(V) oxide tribromide (NbOBr,) when treated with phthalonitrile in 1-chloronaphthalene at 230CC for 3 hours produces /r-bromo-/t-dioxobis[nio-bium(V) phthalocyanine] tribromide in 52%.232... 

Molybdenum(III) complexes include the molybdenum trihaUdes. Molybdenum trichoride [13478-18-7], trifluoride [20193-58-2], tribromide [13446-57-6], and ttiiodide [14055-75-5] are all known. The oxide dimolybdenum trioxide [1313-29-7], M02O2, and the seldom-studied sulfide analogue [12033-33-9], M02S2, are formally trivalent. 

Titanium Dibromide. Titanium dibromide [13873-04-5] a black crystalline soHd, density 4310 kg/m, mp 1025°C, has a cadmium iodide-type stmcture and is readily oxidized to trivalent titanium by water. Spontaneously flammable in air (142), it can be prepared by direct synthesis from the elements, by reaction of the tetrabromide with titanium, or by thermal decomposition of titanium tribromide. This last reaction must be carried out either at or below 400°C, because at higher temperatures the dibromide itself disproportionates. 

Ethylene bromohydrin has been prepared by the reaction between ethylene glycol and hydrobromic acid and phosphorus tribromide. It has also been prepared by the direct addition of hypobromous acid to ethylene, and by the reaction between ethylene and dilute bromine water. With ethylene oxide now available at a reasonable price, the method described is probably the best because of the high yields and the convenience of reaction. 

Fenoldopam (76) is an antihypertensive renal vasodilator apparently operating through the dopamine system. It is conceptually similar to trepipam. Fenoldopam is superior to dopamine itself because of its oral activity and selectivity for dopamine D-1 receptors (D-2 receptors are as.sociated with emesis). It is synthesized by reduction of 3,4-dimethoxyphenylacetonitrile (70) to dimethoxyphenethylamine (71). Attack of diis last on 4-methoxystyrene oxide (72) leads to the product of attack on the epoxide on the less hindered side (73). Ring closure with strong acid leads to substituted benzazepine 74. O-Dealkylation is accomplished with boron tribromide and the catechol moiety is oxidized to the ortho-quinone 75. Treatment with 9NHC1 results in conjugate (1,6) chloride addition and the formation of fenoldopam (76) [20,21]. 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

Pyrrolobenzotriazine 43 was obtained by reaction of 42 with nitrous acid. Its demethylation with boron tribromide gave 44, whose oxidation... 

Griess (1866 b) found that benzenediazonium tribromide (QHsN Br ) in the presence of ammonia is converted into phenyl azide in high yield. The reaction probably proceeds through phenyltriazene, as an intermediate which is subsequently oxidized to the azide by the tribromide ion (Scheme 6-14). 

Molybdenum hexafluoride. 3,1412 Molybdenum-iron-sulfur complexes, 4,241 Molybdenum oxide amino acid formation prebiotic systems, 6, 872 Molybdenum storage protein microorganisms, 6, 681 Molybdenum telluride, 3, 1431 Molybdenum tetraalkoxides physical properties, 2, 347 Molybdenum tribromide, 3,1330 Molybdenum trichloride, 3,1330 Molybdenum trifluoride, 3, 1330 Molybdenum trihalides, 3, 1330 bond lengths, 3, 1330 magnetic moments, 3,1330 preparation, 3,1330 properties, 3, 1330 structure, 3,1330 Molybdenum triiodide, 3,1330 Molybdenum trioxide complexes, 3, 1379 Molybdenum triselenide, 3, 143)... 

Phosphorus pentachloride, for conversion of pentaacetylgluconic add to add chloride, 41, 80 for oxidation of cycloheptatriene to tropylium fluoborate, 43, 101 with cyanoacetic acid, 41, 5 Phosphorus tribromide, reaction with 1.5-hexadien-3-ol, 41, 50 Phthalic anhydride, reaction with L-phenylalanine to yield N-phthalyl-L-phenylalanine, 40, 82 Phthalic monoperacid, 42, 77 N-Phthalyl-i.-alanine, 40, 84 N-Phthalyl-/3-alanine, 40, 84 N-Phthalylglycine, 40, 84 N-Phthalyl-l-/5-phenylalanine, 40, 82... 

BROMINATION AND OXIDATION WITH BENZYLTRIMETHYL-AMMONIUM TRIBROMIDE... 

Our recent studies on effective bromination and oxidation using benzyltrimethylammonium tribromide (BTMA Br3), stable solid, are described. Those involve electrophilic bromination of aromatic compounds such as phenols, aromatic amines, aromatic ethers, acetanilides, arenes, and thiophene, a-bromination of arenes and acetophenones, and also bromo-addition to alkenes by the use of BTMA Br3. Furthermore, oxidation of alcohols, ethers, 1,4-benzenediols, hindered phenols, primary amines, hydrazo compounds, sulfides, and thiols, haloform reaction of methylketones, N-bromination of amides, Hofmann degradation of amides, and preparation of acylureas and carbamates by the use of BTMA Br3 are also presented. 

OXIDATION WITH BENZYLTRIMETHYLAMMONIUM TRIBROMIDE Oxidation of alcohols and ethers... 

There are a number of methods for the oxidation of primary alcohols or ethers to dimeric esters, and secondary alcohols to ketones. We recently also found that quaternary ammonium tribromides, especially BTMA Br3, are useful oxidizing agents for the purpose described above (ref. 31). 

See Chromyl chloride Non-metal halides Oxygen (Gas) Phosphorus tribromide Ruthenium(VIII) oxide Phosphorus tribromide... 

Arsine-boron tribromide See Arsine-boron tribromide Oxidants... 

Macomber and coworkers [38, 39] found that the reaction of 2,2,6,6-tetrame-thyl-4-heptyn-3-ol with phosphorus tribromide led to 3,5-disubstituted-2,5-dihydro-l,2-oxaphosphole-2-oxide derivatives (Scheme 7). 

---