Showing papers on "Boron tribromide published in 1981"
TL;DR: In this paper, a new procedure for the cleavage of aliphatic methyl ethers under mild conditions by the use of the reagents system, boron tribromide - sodium iodide - 15-crown-5 is described.
45 citations
TL;DR: O-demethylation of N-(ethoxycarbonyl)noroxycodone with boron tribromide and subsequent acid hydrolysis gives noroxymorphone, and the results of the singlet oxygen oxidation of the pyrrolidine dienamine derived from N-(ETHoxycarbonol)norcodeinone are described.
Abstract: Codeine is converted to 7,8-dihydro-14-hydroxynorcodeinone (noroxycodone) in six steps and 52% overall yield of the noroxymorphone in seven steps and 43% overall yield. N-Demethylation and oxidation of codeine afford N-(ethoxycarbonyl)norcodeinone, which is converted to its dienol acetate derivative and oxidized with singlet oxygen to give N-(ethoxycarbonyl)-14-hydroxynorcodeinone in the key step. Hydrogenation of the latter affords N-(ethoxycarbonyl)noroxycodone, which upon acid hydrolysis yields noroxycodone. Alternatively, O-demethylation of N-(ethoxycarbonyl)noroxycodone with boron tribromide and subsequent acid hydrolysis gives noroxymorphone. The results of the singlet oxygen oxidation of the pyrrolidine dienamine derived from N-(ethoxycarbonyl)norcodeinone are also described.
41 citations
TL;DR: In this article, the authors described the catalytic hydrogenation of carbon monoxide with Os/sub 3/(CO)/sub 12/ as a catalyst precursor and boron tribromide as a solvent, catalyst promoter, and ultimate reactant.
Abstract: The catalytic hydrogenation of carbon monoxide with Os/sub 3/(CO)/sub 12/ as a catalyst precursor and boron tribromide as a solvent, catalyst promoter, and ultimate reactant is described. Reaction conditions were relatively mild: 180/sup 0/C and approx. 2 atm. The hydrogenation products were unique and included methane, ethane, propane, isobutane, neopentane, methyl bromide, ethyl bromide, propyl bromides, and butyl bromides. The major products were methyl and ethyl bromides. During the course of the catalytic reaction Os/sub 3/(CO)/sub 12/ was converted to Os/sub 2/(CO)/sub 6/Br/sub 4/. The latter was shown to function as a catalyst precursor to produce a similar range of hydrocarbon and alkyl bromide products. Substitution of BCl/sub 3/ for BBr/sub 3/ gave an analogous reaction system. Conversion of Os/sub 3/(CO)/sub 12/ to Os/sub 3/(CO)/sub 10/Cl/sub 2/ and Os/sub 2/(CO)/sub 6/Cl/sub 4/ was established for the CO hydrogenation system. The BCl/sub 3/ reaction system was, however, sharply differentiated from the BBr/sub 3/ system in that only hydrocarbons were produced; no alkyl chloride products were detected.
15 citations
TL;DR: The ability of boron tribromide to break ether bonds quantitatively was demonstrated by cleavage of model ethers as discussed by the authors, which can be easily applied to other ether-linked ligands.
15 citations
TL;DR: In this article, the experimental growth rate of boron obtained by pyrolysis of under reduced pressure was studied. But the growth rate is a function of temperature and of surface coverage, hence of pressure.
Abstract: We have studied the experimental growth rate of boron obtained by pyrolysis of under reduced pressure. Results are interpreted assuming that is adsorbed with dissociation on the boron surface, with no activation energy. Boron combines with the underlying lattice. Bromine is chemisorbed in the form of atoms. Bromine may either desorb in atomic form, or it may recombine and desorb in a molecular form or in the form of a bromide. The growth rate is a function of temperature and of surface coverage, hence of pressure. There is a good fit between the experimental results and the theoretical calculations. The deposition yield depends on the flow rate and on the pumping speed in the reactor.
13 citations
11 citations
TL;DR: The molecular structure of trimethylphosphine-boron tribromide (CH3)3P·BBr3 has been determined from gas electron-diffraction and vibrational-spectroscopic data as mentioned in this paper.
Abstract: The molecular structure of trimethylphosphine–boron tribromide (CH3)3P·BBr3 has been determined from gas electron-diffraction and vibrational-spectroscopic data. The molecular parameters and their uncertainties were rg(B–Br)=2.010±0.009 A, rg(P–B)=1.946±0.029 A, rg(C–P)=1.804±0.004 A, rg(C–H)=1.098±0.010 A, ∠BrBBr=111.7±0.7°, and ∠CPC=108.0±0.7°. The potential barrier around the P–B bond was also estimated to be about 10 kcal mol−1 (1 cal=4.184 J).
7 citations
TL;DR: When Me n SnX 4− n compounds (n = 3, 2 or 1) are dissolved in liquid BX 3 (where X = Cl or Br) at room temperature, a reaction occurs which may involve either halogen exchange alone or the cleavage of a methyl group from the alkyltin compound accompanied by halogene exchange.
3 citations
Patent•
16 Sep 1981
TL;DR: In this paper, an 8,9-dihydroxyphenanthridinium salt of formula I (R is lower alkyl; X is anion) was used as a carcinostatic agent.
Abstract: NEW MATERIAL:A 8,9-dihydroxyphenanthridinium salt of formula I (R is lower alkyl; X is anion). EXAMPLE:8,9-Dihydroxy-5-methylphenanthridinium chloride. USE:Useful as a carcinostatic agent. PROCESS:2,4,5-Trimethoxybenzoic acid is made to react with thionyl chloride in ether, and the reaction product is reacted with aniline. The resulting compound is irradiated with light in a solvent, and reacted with an alkyl halide of formula R - Y(Y is halogen) in the presence of a base to obtain a compound of formula II, which is converted to a compound of formula III by the reaction with boron tribromide followed by hydrolysis. The compound of formula III is reduced in an inert solvent with a reducing agent to obtain a compound of formula IV, which is oxidized with air in a solvent containing a halogen acid to afford the compound of formula I.
2 citations
TL;DR: In this article, the experimental growth rate of boron obtained by pyrolysis of under reduced pressure was studied. But the growth rate is a function of temperature and of surface coverage, hence of pressure.
Abstract: We have studied the experimental growth rate of boron obtained by pyrolysis of under reduced pressure. Results are interpreted assuming that is adsorbed with dissociation on the boron surface, with no activation energy. Boron combines with the underlying lattice. Bromine is chemisorbed in the form of atoms. Bromine may either desorb in atomic form, or it may recombine and desorb in a molecular form or in the form of a bromide. The growth rate is a function of temperature and of surface coverage, hence of pressure. There is a good fit between the experimental results and the theoretical calculations. The deposition yield depends on the flow rate and on the pumping speed in the reactor.