Butylbromide Research Articles

An electrochemical and spectroelectrochemical (IR) investigation of the reduction of RCo(II)TPP (R=benzyl or butyl; TPP=tetraphenylporphyrin): mechanistic implications in the CoTPP catalyzed electrocarboxylation of alkyl halides

Abstract The electrochemical reduction of the intermediates generated from the reaction of Co(I)TPP− (TPP=tetraphenyl porphyrin) with benzyl chloride (PhCH2Cl) or butyl bromide (BuBr) have been studied by use of electrochemistry and IR-spectroelectrochemistry. The rates of formation of PhCH2Co(III)TPP, and of decomposition of the reduction product [PhCH2Co(II)TPP]− are much faster than those found for the corresponding BuBr system. The decomposition of [RCo(II)TPP]− proceeds via homolytic CoC bond cleavage, to generate the corresponding organic radical at negative potential, where RCo(III)TPP can be reduced to [RCo(II)TPP]−. A mechanism involving the reaction of organic radicals with the porphyrin ring and transfer from cobalt to a nitrogen of the pyrrole ring, leading to the formation of an N-alkyl cobalt porphyrin complex is proposed, which is consistent with the destruction of catalyst during electrocatalytic carboxylation and reduction of an organic halide.

Facile preparation of pyrylium and pyridinium bromides under neutral conditions

Abstract Pyrylium and pyridinium bromides may be prepared in virtually quantitative yield by reaction of the corresponding base with an excess of tert -butyl bromide under reflux in chloroform solution.

Synthesis and alkylation of pyridylacetylenes under phase transfer catalysis conditions in a liquid/solid system

We have investigated the alkylation of 2-methyl-5-ethynylpyridine by butyl bromide in liquid/liquid and liquid/solid two-phase catalytic systems. We have shown that the catalytic system solid KOH/18-crown-6/CuBr/toluene is the most active in this reaction; using this system, we obtained alkylation products of ethynylpyridines in 34–43% yields.

Crystal Structure and Chemical Properties of Tris(2,6-dimethoxyphenyl)phosphine Selenide

Abstract The X-ray crystal structure of the title compound, Φ3PSe [Φ = 2,6-(MeO)2C6H3], showed that the P=Se bond distance [2.136(2) Å] was the longest among those of the reported triarylphosphine selenides, that the P–C bond distances [av. 1.839 Å] were longer than those of triphenylphosphine selenide, and that all the P···O interatomic distances [2.794—3.189 Å] were shorter than the sum of the van der Waals radii, implying a direct electron-donative interaction from the methoxy oxygen atom to the phosphorus atom. Some chemical evidence also showed that the P=Se bond was weaker than that of triphenylphosphine selenide. Alkyl halides, RX, reacted with Φ3PSe to give a mixture of alkylselenophosphonium salts, [Φ3P–SeR]X, and alkylphosphonium salts, [Φ3P–R]X, while they reacted with PhΦ2PSe to give [PhΦ2P-SeR]X almost selectively. Measurements of the reaction rates of Ph3−nΦnPY (n = 0—3; Y = none, O, S, Se) with butyl bromide in acetonitrile showed that the rate decreased in the order of Y = none > Se > S > O and n = 3 > 2 > 1 > 0. Benzylselenophosphonium salts, [Φ3P–SeCH2C6H4Z-4]Cl (Z = H, Me, Cl) and [PhΦ2P–SeCH2Ph]Cl, reacted easily with aqueous sodium hydroxide or with aqueous tin(II) chloride to give the diselenides, (4-ZC6H4CH2Se)2, and most of ArΦ2P [Ar = Φ or Ph] was recovered after these reactions. These properties of [ArΦ2P–SeR]X, as well as of ArΦ2PSe, were discussed in terms of the electronic effect and/or steric effect of methoxy groups at 2,6-positions.

Reactions of tris(2,6-dimethoxyphenyl)arsine, tris(2,6-dimethoxyphenyl)stibine and tris(2,6-dimethoxyphenyl)bismuthine and their derivatives

Tris(2,6-dimethoxyphenyl)arsine and tris(2,6-dimethoxyphenyl)stibine ( Φ 3M( Φ = 2,6-(MeO) 2C 6H 3; M = As an Sb)) reacted with common alkyl halides (RX) to give [Φ 3M-R]X, while Φ 3Bi was unreactive in benzene, or it decomposed in hot alcohols. The reactions of Φ 3M (As, Sb) with butyl bromide in acetonitrile were much faster than that of triphenylphosphine. Treatments of Φ 3M (P, As, Sb)with N-bromosuccinimide (NBS) gave [Φ 3M−OH]Br, while Φ 3Bi decomposed to give 1-bromo-2,6-dimethoxybenzene. [Φ 3M-OH]Br are soluble in water, and the acidity decreased in the order M = P > As > Sb. Treatments of Φ 3M(As, Sb) with aqueous hydrogen peroxide gave the oxides as hydrates, φ 3MO. xH 2O ( x = 1, for M = As and x = 3 for M = Sb), while Φ 3Bi was unreactive or decomposed. Φ 3PO was brominated by NBS to give Φ 3'PO.H 2O ( Φ = 3-Br-2,6-(MeO) 2C 6H 2), which did not react with perchloric acid. In contrast, Φ 3MO. xH 2O (P, As, Sb) reacted with the acid to form the stable hydroxyonium salts [Φ 3M−OH]ClO 4. [Γ 3POH]ClO 4 formed crystals of stable 1 : 1 adducts with a variety of amines. [Φ 3AsOH]ClO 4 formed 1 : 1 adducts when treated with excess amounts of several amines (triethylamine, diethylamine, isobutylamine and piperidine), but they were unstable to leave amines by recrystallization. [Φ 3 SbOH]ClO 4 formed unstable adducts with these amines, or it did not form. [Φ 3PSH]ClO 4 formed 1 : 1 adducts with several amines, or it was deprotonated to give Φ 3MO. xH 2O (P,As) reacted with common RX (X - Br or I) to give [Φ 3M-OR]X, but but φ 3SbO. 3H 2O reacted to give Φ 3SbOH]X. [Φ 3POR]X decomposed reversibly to give Φ 3PO in solutions, although [Φ 3MOR]ClO 4 (P, As) could be recrystallized.

Synthesis, Lipophilicity, and Stability of Tetrakis (pentafluorophenyl) borate (FTPB) Anion under Highly Acidic Conditions in Comparison with Those of Tetrakis (3,5-bis (trifluoromethyl) phenyl) borate (TFPB) Anion

An improved synthetic method for tetramethylammonium FTPB by a metal-halogen exchange reaction of pentafluorophenyl bromide with magnesium in the presence of a catalytic amount of butyl bromide and by a subsequent reaction with boron trifluoride diethyl ether was developed. The lipophilicity of tetramethylammonium FTPB in a range of hydrophobic organic solvents and its stability under highly acidic conditions were investigated in comparison with those of tetramethylammonium TFPB.

A study of the mechanism of solvoysis of but-3-enyl bromide (4-bromobut-1-ene) using the extended (two-term) Grunwald–Winstein equation

The solvolysis of but-3-enyl bromide at 70 °C follows the SN2 mechanism over a wide variety of solvent as indicated by a sensitivity to changes in solvent nucleophilicity (l value) of 0.99 ± 0.04, specific rates of solvolysis of about on-half of those for the saturated butyl bromide and a kOTs/kBr ratio in ethanol of 12, essentially indentical with the value previously observed for ethanolyses of methyl and ethyl derivatives. There are indications of a minor (about 35%) SN1 component to the solvolysis in 97% TFE, which becomes dominant in 90% HFIP. Kinetic analysis suggest, consistent with previous product studies, only an approximately 4% SN2 component to a dominant SN1 formolysis of the corresponding tosylate.

The amine modified acrylic copolymers as catalysts in the reaction of octylbromide with sodium cyanide

Amine-modified and alkylated (with butyl bromide or hexyl bromide) acrylonitrile-butyl acrylate-divinylbenzene terpolymers and alkyl acrylate-divinylbenzene copolymers (where alkyl=methyl, ethyl or butyl) were used as catalysts in the reaction of octyl bromide with cyanide anions. The dependence of catalytic activity as a function of the acrylate content and swelling properties was investigated. The most effective catalyst was butyl acrylate-divinylbenzene copolymer. This sample showed maximum toluene uptake from the toluene/water mixture.

Electrochemically induced formation of organomercury compounds

A procedure for the alkylation of metallic mercury by (dimethylglyoximato)butylcobalt(III) electrochemically generated in the presence of butyl bromide is proposed.

Reactivity of Interstitial Cl− Anions in Synthetic Hydrotalcite-Like Materials in the Halide Exchange Reaction with Alkyl Halides

ABSTRACTTwo types of synthetic hydrotalcite-like [Mg6Al2(OH)16 ][An−%D;2/n (HT) were prepared where A = Cl− anions (Cl-HT), and NiC42− complex anions (NiCl-HT), in order to examine: (1) the reactivity of Cl− anion (or ligand) towards alkyl halides and (2) their catalytic behavior in the Finkelstein reaction. For instance, 0.4 g of NiCl-HT (Cl−: 1.41 mmol) suspended in 20 cm3 of toluene with 14.1 mmol of butyl bromide at 373 K yielded 42 % butyl chloride after 15 min of reaction. In comparison, NiCl4(Et4N)2 (precursor to prepare NiCl-HT) yielded at the same conditions only 2.4 % of butyl chloride. This indicates a great mobility of Cl− in the interlayer region of HTs. The reaction rate is greatly accelerated using DMF instead of toluene and butanol totally suppressed it. This is consistent with a SN2 mechanism. The halide-exchange reaction between benzyl chloride and butyl bromide is catalyzed by both Cl-HT and NiCl-HT.

Reactivity of interstitial [NiCl 4] 2− complex anions in a MgAl hydrotalcite-like clay towards alkyl bromides in the liquid phase

The chloride ligands in [NiCl 4] 2− ions in the interlayers of a MgAl hydrotalcite-like clay (NiClHT) are completely exchanged with bromide in alkyl bromide in the liquid phase. The solvent exerts a very strong effect on the reactivity of interlamellar Cl − anions in NiClHT towards butyl bromide. Thus, all the interstitial Cl − anions of the interlayer [NiCl 4] 2− ions appear as butyl chloride after 15 min in DMF, while in decane or toluene only 52 and 41% of interstitial Cl −, respectively, after 15 min, were found in the organic phase. The use of butanol as a reaction solvent results in complete inhibition of the reaction. [NiCl 4] 2− complex anions in NiClHT are isomorphically transformed into tetrahedral [NiBr 4] 2− by halide exchange with butyl bromide in DMF. NiClHT can be used as a heterogeneous catalyst in the halide exchange between benzyl chloride and butyl bromide in DMF or in toluene.

Synthesis and characterization of positively charge-modified polyproplyene membrane

A technique for incorporating positively charged groups onto the surface of microporous polypropylene membrane filters is described. In this method, 4-vinyl-pyridine is polymerized and grafted onto polypropylene membranes using /sup 60/Co gamma -irradiation. Pyridyl groups on the grafted membranes are quaternized with butyl bromide. The electrical characteristics of prepared membranes were measured by streaming potential and anionic dye challenge tests. The compatibility of these charge-modified membranes with ultrapure water is investigated. Results show that these charge-modified membranes are characterized by a positive zeta potential in the pH range from 4 to 9.3. From the dye challenge test at a pH of 5.0, the density of positively charged sites was calculated to be 1.7*10/sup 19/ sites/g. The membranes did not release any measureable total oxidizable carbon (TOC) into ultrapure water and thus appear to have potential for use in deionized (DI) water system. >

2H-1,4-Benzotellurazin-3(4 H)-one and its Derivatives

A novel tellurium-containing heterocycle, 2 H -1,4-benzotellurazin-3(4 H )-one 1 has been prepared by treatment of butyl 2 -aminophenyl telluride 2 with either bromoacetic acid or bromoacetyl chloride and subsequent elimination of butyl bromide from the tellurazinium compound 3 so formed.

Kinetics and steric limitation of quaternization of poly(4‐vinylpyridine) with mesogenic ω‐(4′‐methoxy‐4‐biphenylyloxy)alkyl bromides

AbstractThe kinetics and characteristics of the quaternization of poly(4‐vinylpyridine) with very large alkylating agents are studied with the main aim to demonstrate the occurrence of a limitation of the reaction due to steric effect. Kinetics are carried out in sulfolane at different temperatures with two ω‐(4'‐methoxy‐4‐biphenylyloxy)alkyl bromides. An important limitation of the reaction is demonstrated: 30% of the pyridine groups are inaccessible at 333 K, 23% at 355.5 K, and 4% at 363 K. Post‐quaternization experiments with butyl bromide of already partially quaternized P4VP also demonstrate this limitation. The occurrence of global steric hindrance and hydrophobic effects affecting the conformation of the chain in solution is proposed to explain the limited accessibility of the pyridine groups. The results question the classical neighboring group model generally used to describe the slowing down of the quaternization reaction with increasing quaternization ratio. The thermal stability of the quaternized polymers and the colors of the reaction medium are also discussed. © 1992 John Wiley & Sons, Inc.

ChemInform Abstract: Convenient Stereoselective Syntheses of 6E‐ and 6Z‐5,6‐Dimethyl‐8‐silyl‐6‐octenals.

AbstractThe Z‐enol phosphate (IV) is produced by consecutive reaction of the dianion of the β‐keto ester (I) with the butyl bromide (II) and the chlorophosphate (III).

Catalysis by synthetic hydrotalcite-like materials in halide exchange between alkyl halides

Synthetic hydrotalcite-like materials, ▪, were used as catalysts for the halide-exchange reaction between benzyl chloride and alkyl bromides in DMF or toluene. A material with M 2+ = Mg 2+, M 3+ = Al 3+ and x = 0.25 showed the highest activity. In the presence of 1 g of the material, containing 3.3 mmol of exchangeable interlayer Cl − anions, reaction between benzyl chloride (33 mmol) and butyl bromide (33 mmol) in toluene at 373 K for 4 h gave benzyl bromide in 31% yield; in the absence of the material the reaction does not proceed. A 90% yield of benzyl bromide was attained in the reaction in DMF at 343 K for 20 h when 195 mmol of butyl bromide and 33 mmol of benzyl chloride were used. Interlayer Cl − anions of the hydrotalcite-like materials are capable of migrating to external edge surfaces at which halide exchange reactions proceed. Ethyl bromide, propyl bromide and 1,4-dibromobutane are also effective bromination agents. The material is also an effective catalyst for a halide exchange reaction between benzyl chloride and butyl iodide. The halide exchange between a hydrotalcite-like material containing Cl − anions and organic bromides is also examined and the reaction mechanism of the halide exchange is discussed.

Effects of buscopan on gastro-oesophageal reflux and hiatus hernia

This prospective study was undertaken to establish whether Buscopan (hyosine butyl bromide) interferes with the detection of a hiatus hernia or induces gastro-oesophageal reflux. One hundred and four consecutive patients were included in the study who came for barium meal and swallow examinations over a period of 3 months. Ten patients were excluded from the study. The examinations were performed by the author. The manoeuvres to detect gastro-oesophageal reflux and hiatus hernia were performed before and after intravenous Buscopan. It was found that Buscopan does not induce gastro-oesophageal reflux in the majority of patients, or interfere with detection of a hiatus hernia. The conclusion of this study is that Buscopan can be given early on in the barium meal examination without a significant effect on hiatal function.

The evidence and applications of equilibria between hydroxide and alkoxide ions in aqueous-alcoholic systems

The composition of solvolysis products of butyl bromide, acetanhydride, and benzoyl chloride has been followed aqueous alcohol in alkaline and (except for butyl bromide) also in neutral regions. The results have been used as a piece of evidence of the existence of equilibrium between hydroxide and alkoxide ions and for evaluation of the possibility of calculation of the concentration ratio of hydroxide and alkoxide ions from the concentration ratios of the products as well as for evaluation of selectivities of the solvolytic reactions for mechanistic purposes.

Unvernetzte Epoxid‐Amin‐Additionspolymere, 31. Polykationen auf Basis von Epoxid‐Amin‐Additionspolymeren. Herstellung und Eigenschaften

AbstractNew cationic polymers (4 and 8) with‐defined separation of charges were obtained by N‐quaternization of epoxide‐amine addition polymers with benzyl chloride, butyl bromide and methyl iodide. The termal decomposition of 4 and 8 starts at temperatures between 320 and 370°C. Dielectric measurements in the frequency range 102 to 107 Hz show a dependence of the conductivity on the temperature. The cationic polymer 4d exhibits a conductivity of δ = 10−6 S/cm at 89°C and 106 Hz.

Normal-phase high-performance liquid chromatographic determination of phenols

Normal-phase high-performance liquid chromatography has been used for separation of phenol and its monoderivatives. Multi-component mixtures of hexane (non-polar component) with butan-1-ol, chloroform, butyl bromide, butyl chloride or diethyl ether (polar additives) were used as selective eluents. Silica gel “Silasorb 600” with specific surface area of about 600 m 2/g and average particle size of $ ̃ 10 μm was used as the sorbent. Phenol and the o-, m-, p-isomers of cresol were concentrated by extraction with n-butyl acetate from aqueous solutions. A method for determination of microamounts of phenols in aqueous solutions in the presence of 160-fold amounts of aromatic hydrocarbons has been developed.