N-octyl Bromide Research Articles

Asymmetric synthesis of (S)-α-(octyl)glycine via alkylation of Ni(II) complex of chiral glycine Schiff base.

Over last decade, the use of Ni(II) complexes, derived from of glycine Schiff bases with chiral tridentate ligands, has emerge as a leading methodology for preparation of structurally diverse Tailor-Made Amino Acids, the key structural units in modern medicinal chemistry, and drug design. Here, we report asymmetric synthesis of derivatives of (S)-α-(octyl)glycine ((S)-2-aminodecanoic acid) and its N-Fmoc derivative via alkylation of chiral nucleophilic glycine equivalent with n-octyl bromide. Under the optimized conditions, the alkylation proceeds with excellent yield (98.1%) and diastereoselectivity (98.8% de). The observed stereochemical outcome and convenient reaction conditions bode well for application of this method for large-scale asymmetric synthesis of (S)-2-aminodecanoic acid and its derivatives.

Synthesis and Structural Investigation of Some Transition Metals Complexes of Benzimidazolium Bromide

The present work involves the synthesis of novel imidazolium salts of bromide in step-wise reactions which are started from preparation of 2,4-dimorpholine-6-(1H-benzimidazole-1-yl)-1,3,5-triazine (1) in potassium hydroxide and DMF solvent followed by substitution reactions with n-butyl bromide and n-octyl bromide to afford the new ligands names L1 = 1-(2,4-dimorpholino-1,3,5-triazine-2-yl)-3-butyl-1H-benzimidazol-3-ium bromide and L2 = 1-(2,4-dimorpholino-1,3,5-triazine-2-yl)-3-octyl-1Hbenimidazol-3-ium bromide. The new ligands were recrystallized from hot chloroform and the following of reactions completion were carried out by thin layer chromatography (TLC). The formula and structures of the two salts of benzimidazolium bromide were confirmed on the basis of measurements of (CHN) elemental analyses, FT-IR, NMR and EIMS spectroscopy. Furthermore the manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized from the direct reactions of their hydrated metal salts in methanol with the solutions of the ligands in chloroform in 1:1 mole ratio and the analytical data of atomic absorption spectroscopy and elemental analyses revealed the proposed formula of the solid metal complexes. The data obtained from FT-IR, UV-Visible spectra, molar conductivity and magnetic susceptibility measurements confirmed the octahedral environment around cobalt(II) ion in [CoL(H2O)2Cl2] and the tetrahedral geometry was adopted for manganese(II) and zinc(II) ions. However the square-planner structure was expected for the copper(II) and nickel(II) complexes in [MLCl2], M = Ni(II) and Cu(II) ions and L = L1 and L2 ligands. As well as the suitable and favourable active sites in the two ligands L1 and L2 were the two nitrogen atoms of morpholine rings which has been observed from FT-IR spectra and the kinetic stability of five-member ring up on chelation with the metal ions supported the conclusion of the symmetry.

Kinetics for Synthesis of 1-Octanethiol

The reaction kinetics of synthesis of 1-oetanethiol from the sodium hydrosulfide and n-octyl bromide using tetrabutyl ammonium bromide as the phase transfer catalyst was studied. The reaction kinetic model Was established Through the experimental verification, the reaction kinetics can be described by first order reaction kinetics as r(A) = -dc(A)/dt = 7.97973x10(7) exp(-7073.9/T)c(A). The apparent activation energy of the reaction was 58.815 KJ mol(-1). The calculated results using the kinetics parameters from the kinetic Model; agree well with the experimental data

Dielectric study of novel liquid crystals based on calix[4]arene Schiff bases

Novel liquid crystals based on calix[4]arene Schiff bases have been synthesised by the reaction of tetra-amino-calix[4]arene with two aldehydes (4-hydroxy benzaldehyde and 4-vanillin), further substituted with alkyl chains (n-butyl bromide and n-octyl bromide) on both the upper and lower rim by substitution of the hydroxyl groups of the calix[4]arenes. These derivatives were purified and characterised by elemental analysis and Fourier transform infrared, 1H and 13C nuclear magnetic resonance and matrix-assisted laser desorption/ionisation time of flight mass spectrometry. The compounds were investigated for liquid crystalline properties using differential scanning calorimetry, differential thermal analysis, X-ray diffraction, and polarising optical microscopy with a heating assembly. All the compounds were found to exhibit nematic structure and a typical fanlike or mosaic texture, which suggests an ordered smectic mesophase. Dielectric investigations were also carried out and showed N, SmA and SmC phases. Dielectric permittivities (ϵ′ and ϵ″) were determined at a variety of temperatures (45–95°C) over a range of frequency between 20 Hz and 2 MHz.

Synthesis and Characterization of Sodium N,N'-dioctyl-ethylenediamine Diacyl Propionate

Sodium N,N'-dioctyl-ethylenediamine diacyl propionate, an anionic gemini surfactant, was synthesized byethylenediamine with n-octyl bromide, followed by reaction with succinic anhydride, cesium hydroxide andtriethylamine as catalyst, through N-alkylation and N-acylation. Structure of the intermediate and final product wascharacterized by infrared spectrometer and nuclear magnetic resonance apparatus. The influences of material ratio andreaction time on the N-alkylation product yield were investigated. Experimental results showed that the yield of theN-alkylation product reached up to 64% under the optimum reaction conditions, the yield of the N-acylation productwas 39%.

Microenvironmental effect on phase-transfer catalytic activity of polymeric formamides

Polymeric formamides (Pl) were prepared by the copolymerization of N-methyl- N-( p-vinylbenzyl)formamide (MVFA) with styrene by AIBN at 60°C. Similarly copolymerization of MVFA with other hydrophobic monomers such as p-fluorostyrene, p-tert-butylstyrene, and p-trimethylsilylstyrene afforded the corresponding polymers (P2-P4), respectively. These polymers displayed the catalytic activity for the reaction of n-octyl bromide with alkali-metal thiocyanates in liquid-liquid two-phase system. The catalytic activity of P2-P4 was superior to that of P1. This finding was understood by considering that the degree of desolvation of nucleophile could be increased by using more hydrophobic monomers instead of styrene to lead the enhancement of reaction rate. The polymer composition which shows the maximum catalytic activity depends strongly on alkali-metal cations in attacking agents.

Synthesis of long chain aromatic esters in a solvent-free procedure under microwaves

Alkylation with n-octyl bromide of several substituted benzoic acids was performed under solvent-free phase transfer catalysis with excellent yields (≥ 95%) within very short times (2–7 min). Terephthalate octylation was raised from 20% to 92% under microwave activation when compared to conventional heating thanks to intrinsec effects of the radiation.

Preparation of Polystyrenes Containing Sulfonamide Moieties and Their Use as Phase Transfer Catalysts

Abstract Styrenes containing sulfonamide moieties such as N-methyl-N-(P-vinylbenzyl)methanesulfonamide and N,N-dimethyl-p-styrene-sulfonamide were prepared. The copolymerization parameters of these monomers were obtained from copolymerization with styrene under free radical conditions. Crosslinked polymers prepared by free radical terpolymerization of the sulfonamide monomer, styrene, and divinylbenzene served as phase transfer catalysts for the reaction of n-octyl bromide with sodium thiophenoxide in the toluene-water system. However, the corresponding monomeric sulfonamides were practically inactive. These polymer catalysts were stable even under strongly alkaline conditions, and the recovered catalysts were used without a significant loss in activity.

ChemInform Abstract: Free‐Radical Carbonylation. Efficient Trapping of Carbon Monoxide by Carbon Radicals.

The authors examined the AIBN-induced radical reaction of n-octyl bromide (1) (Scheme 1) with Bu{sub 3}SnH under CO pressure in hope of trapping of carbon monoxide by octyl radical followed by hydrogen abstraction from tin hydride. When the reaction on a 0.5-mmol scale was conducted under CO pressure, using an autoclave with an inserted glass tube (5 mol % of AIBN, benzene (10 mL), 80{degree}C, 3 h), the desired aldehyde 2 was obtained together with n-octane (3), formed via simple reduction of 1. Surprisingly, this radical/CO trapping sequence proceeds even at 15 atm of CO pressure to give 2 in 38% yield (run 2). Generally, higher pressures of CO resulted in the increase of 2. These results demonstrate that the control of the relative concentrations of CO to tin hydride is an important factor to effect the CO trapping leading to aldehyde 2.

Free radical carbonylation. Efficient trapping of carbon monoxide by carbon radicals

The authors examined the AIBN-induced radical reaction of n-octyl bromide (1) (Scheme 1) with Bu{sub 3}SnH under CO pressure in hope of trapping of carbon monoxide by octyl radical followed by hydrogen abstraction from tin hydride. When the reaction on a 0.5-mmol scale was conducted under CO pressure, using an autoclave with an inserted glass tube (5 mol % of AIBN, benzene (10 mL), 80{degree}C, 3 h), the desired aldehyde 2 was obtained together with n-octane (3), formed via simple reduction of 1. Surprisingly, this radical/CO trapping sequence proceeds even at 15 atm of CO pressure to give 2 in 38% yield (run 2). Generally, higher pressures of CO resulted in the increase of 2. These results demonstrate that the control of the relative concentrations of CO to tin hydride is an important factor to effect the CO trapping leading to aldehyde 2.

Preparation of some polymer-supported crown ethers and their use as phase-transfer catalysts

Benzo-15-crown-5 and dibenzo-18-crown-6 have been formylated. The products were then bound to diol-containing crosslinked polystyrenes via acetalisation and to crosslinked polymers containing benzyltriphenylphosphonium chloride residues (obtained by treating chloromethylated polystyrenes with triphenylphosphine)via phase-transfer catalysed Wittig reactions. The various polymer-supported crown ethers have been found to be satisfactory phase-transfer catalysts for the reactions of n-octyl bromide in toluene with aqueous potassium iodide at 90 °C and with aqueous sodium p-methylthiophenolate at 80 °C, but not for the reaction of n-octyl bromide in toluene with aqueous potassium cyanide at 90 °C. The crosslinked polymers containing benzyltriphenylphosphonium chloride residues were also satisfactory catalysts for the first two reactions.

ChemInform Abstract: TETRAKIS(SULFOXIDES) AS PHASE TRANSFER CATALYSTS

AbstractAnhand der Umsetzungen von Octylbromid mit Kaliumrhodanid, Kaliumcyanid, Kaliumphenolat bzw. Kaliumthiophenolat wird untersucht, inwieweit die im Formelschema vorgestellten Verbindungen als Phasentransfer‐Katalysatoren dienen können.

TETRAKIS-SULFOXIDES AS PHASE TRANSFER CATALYSTS

Abstract Tetrakis(alkyl-sulfinylmethyl)methanes serve as highly efficient phase transfer catalysts in SN2 type displacement reactions of n-octyl bromide with a few nucleophiles.

Improved methods for conversion of primary amines into bromides

N-Alkyl- and N-benzyl-4-p-chlorophenyl-2,3,5,6-tetraphenyl-N-alkyl- and N-benzyl-2,3,4,5,6-pentaphenyl-, and N-alkyl- and N-benzyl-2,4,6-triphenyl-pyridinium bromides on pyrolysis at 180–220 °C give the corresponding alley and benzyl bromides in high yield. 1-Benzyl-5,6-dihydro-2,4-diphenylbenzo[h]quinolinium trifluoromethanesulphonate gave benzyl bromide on heating with KBr in dimethylformamide at 100 °C, and n-octyl bromide (80%) was obtained from the corresponding pentacyclic bromide in refluxing acetonitrile.

Quaternary ammonium bromide catalyzd chloride for bromide redistributions between carbon of alkyl halides and tin of tri-n-butyltin halides

Quaternary ammonium bromides have been found to strongly catalyze reversible chloride for bromide substitution reactions by tri-n-butyltin chloride on benzyl bromide and n-octyl bromide. However, they have only a small effect upon the rate of the corresponding reaction with benzhydryl bromide. It is suggested that the catalytic effect involves initial coordination of bromide ion with tri-n-butyltin chloride to form a nucleophilic anionic complex containing pentavalent tin which is reactive for backside displacements at carbon of sterically unhindered alkyl halides. No catalytic effects could be demonstrated, however, for ligands such as pyridine or N, N-dimethylformamide which could potentially form zwitterionic complexes with tri-n-butyltin chloride.

Kinetics of hydrolysis of n-hexyl bromide, n-heptyl bromide, and n-octyl bromide in alkaline and neutral media

Data obtained in the kinetic study of the hydrolysis of n-hexyl, n-heptyl, and n-octyl bromide in alkaline and neutral media at different temperatures and in varying ethanol-water mixtures are reported. The rate constants for the three reactions (bimolecular and unimolecular substitution, and bimolecular elimination) which occur simultaneously have been calculated for each compound.

Molecular Motion in Liquid n-Octyl Bromide by Proton Magnetic Resonance

Molecular Motion in Liquid n-Octyl Bromide by Proton Magnetic Resonance