The Chemical Ionization of Organic Compounds. 1st Communication. Linear alkenes with six to nine carbon atoms

The chemical ionization spectra of linear alkenes have been measured using H₂O, CH₄ or CD₃OD as ionizing gas. In the case of 1-heptene the dependence of spectra on pressure, temperature and repeller field strength has been measured and is discussed.     

Physico-Chemical Properties of Deuteriated Compounds. 2nd Communication. The isotope partition coefficient in methylcyclohexane-hydrogen

The deuterium isotope partition coefficient α has been determined as a function of total pressure, temperature and degree of deuteriation for methylcyclohexane/hydrogen over Ni/Al₂O₃. Good agreement with theory has been obtained for the dependence on temperature but not for that on total pressure or on the degree of deuteriation.     

Carbonylation of Tertiary Alkyl Halides Synthesis of Pivaloyl Halides

The carbonylation of tert-butyl halides in a two-phase system, RSO₃H/CCl₄, under carbon monoxide pressure affords the corresponding pivaloyl halides in good yields and selectivities.     

New Carbonyl Compounds in the High-Boiling Fraction of Lavender Oil. 2nd Communication

In addition to the sesquiterpenoid compounds reported in [1] the in-depth analysis of lavender oil also led to the identification of new constituents with caryophyllane ( 1 – 6 ), cedrane ( 7 and 8 ) and other skeletons ( 9 – 21 ). Spectroscopic properties as well as partial syntheses of these compounds are discussed.     

Reactions of O2 --Containing Supramolecules with Alkyl Halides

Formation of O₂ ^--containing supramolecules generated from the system 18-crown-6-KO₂ and electrochemically (tetraethylammonium superoxide) and the kinetics of the reactions of the generated O₂ ^- with alkyl halides in acetonitrile were studied conductometrically and UV-spectrophotometrically; the kinetic parameters of the processes were determined. The E2 mechanism was suggested for the reaction.     

Nickel-Catalyzed Electrochemical Reductive Relay Cross-Coupling of Alkyl Halides to Aryl Halides

A highly regioselective Ni-catalyzed electrochemical reductive relay cross-coupling between an aryl halide and an alkyl halide has been developed in an undivided cell. Various functional groups are tolerated under these mild reaction conditions, which provides an alternative approach for the synthesis of 1,1-diarylalkanes.     

Cross‐Electrophile Coupling of Vinyl Halides with Alkyl Halides

An improved method for the reductive coupling of aryl and vinyl bromides with alkyl halides that gave high yields for a variety of substrates at room temperature with a low (2.5 to 0.5 mol %) catalyst loading is presented. Under the optimized conditions, difficult substrates, such as unhindered alkenyl bromides, can be coupled to give the desired olefins with minimal diene formation and good stereoretention. These improved conditions also worked well for aryl bromides. For example, a gram‐scale reaction was demonstrated with 0.5 mol % catalyst loading, whereas reactions at 10 mol % catalyst loading completed in as little as 20 minutes. Finally, a low‐cost single‐component pre‐catalyst, (bpy)NiI₂ (bpy=2,2′‐bipyridine) that is both air‐ and moisture‐stable over a period of months was introduced.     

Cobalt-Catalyzed Asymmetric Remote Borylation of Alkyl Halides

Enantioselective functionalization of racemic alkyl halides is an efficient strategy to assemble complex chiral molecules, but remains one of the biggest challenges in organic chemistry. The distant and selective activation of unreactive C−H bonds in alkyl halides has received growing interest as it enables rapid generation of molecular complexity from simple building blocks. Here, we reported a cobalt-catalyzed remote borylation of alkyl (pseudo)halides (alkyl−X, X=I, Br, Cl, OTs) with pinacolborane (HBpin) and presented a robust approach for the generation of valuable chiral secondary organoboronates from racemic alkyl halides. This migration borylation reaction is compatible with primary, secondary, and tertiary bromides, offering direct access to a broad range of alkylboronates. The extension of this catalytic system to the borylation of aryl halides was also demonstrated. Preliminary mechanistic studies revealed that this remote borylation involved a radical reaction pathway.     

The Quantitative Separation of Alkyl and Phenethyl Halides by HPLC

Abstract

A method is described for the quantitative separation of alkyl and phenethyl halides in mixtures containing benzene or toluene. This method involves the isocratic chromatography separation of the mixture, using a ODS column and the detection of the compounds by means of a RI detector.     

The Synthesis of 3,5-Diamino-1,2,4-oxadiazoles. 2nd Communication

The 5-amino-3-arylamino-1,2,4-oxadiazoles 2 are conveniently prepared by oxidative cyclization of the arylamidinoureas 10 . The process is also capable of producing a variety of the 5-substituted-amino analogs 32 when the appropriately substituted guanidine 31 is employed as the substrate. Two different types of rearrangement leading to triazol-3-ones accompany cyclization depending on the choice of starting material. The structures of the rearranged products were established by X-ray crystallographic analysis and the reaction mechanisms leading to these unexpected products are discussed.     

Rate Study of Samarium Diiodide Reduction of Alkyl Halides and 2-Heptanone

Rate constants directly measured from GC-analyzed method for SmI₂ reduction of alkyl halides were obtained. The rates increase in the orders of primary, secondary, tertiary RX and RCl < RBr < RI as expected. 2-Heptanone was chosen as the partner of alkyl halide in the samarium Barbier reaction. In the absence of HMPA, the reaction orders of alkyl halide and ketone were determined as first and zero order, respectively.     

Vinylation of Alkyl Halides Catalyzed by Palladium Catalyst

The palladium catalyzed vinylation of alkyl halides, especially benzyl chlorides, with a variety of olefins has been studied. A possible free radical mechanism was proposed.     

Mechanically Initiated Reaction of Aluminum with Alkyl Halides

Mechanochemical reactions of aluminum with alkyl halides were examined at room temperature. The reaction was initiated by mechanical activation of vibromilling without any activator. It was found that the initiation was not due to the temperature rise at mechanical contact but the active sources formed on aluminum surface by vibromilling. The reactivity of milled aluminum was well correlated with the intensity of exoelectron emission. Both the reactivity and the emission intensity increased sharply after 60 min of milling. The decaying characteristics by exposure of preactivated aluminum were observed for both the reactivity and the emission intensity. The role of exoelectron on the reaction was discussed.     

Photopromoted Carbonylation of Alkyl Halides Under Ambient Conditions

Photopromoted carbonylation of alkyl halides with carbon monoxide can be carried out under ambient conditions with non-precious transition metal complexes(such as cobalt complexes) catalysts.Our preliminary work sowed that alkyl halides can be transformed into alkene and alkane directly under irradiation,but the esters can not be transformed.It is assumed that the carbonylation of alkyl halides may be proceeded in two ways.     

Manganese-Catalyzed Redox-Neutral Thiolation of Alkyl Halides with Thioformates

Transition metal-catalyzed C−S cross-coupling has emerged as an important strategy to furnish thioethers; however, the dominant utilization of noble metal catalysts as well as the construction of challenging C(sp³)−S bonds by transition metal-catalysis remain highly problematic. Earth-abundant manganese has gathered increasing interest as an attractive catalyst for new reaction development; nevertheless, C(sp³)−S cross-coupling reaction by manganese catalysis has not been reported. Herein, we disclose a highly efficient manganese-catalyzed redox-neutral thiolation of a broad range of alkyl halides with thioformates as practical sulfuration agents. Strategically, employing easily synthesized thioformates as thiyl radical precursors allows access to various aryl and alkyl thioethers in good to excellent yields. Notably, this redox-neutral method avoids the utilization of strong bases, external ligands, forcing reaction conditions, and stoichiometric manganese, thus presenting apparent advantages, such as broad substrate scope, excellent functional group compatibility, and mild reaction conditions. Finally, the utilities of this method are also illustrated by downstream transformations and late-stage thiolation of structurally complex natural products and pharmaceuticals.     

Ionization of Organic Compounds Affected by Laser Plasma Radiation at Atmospheric Pressure

Journal of Analytical Chemistry - The results of a study of the pathways of ion formation from organic compounds in Atmospheric Pressure Laser Plasma Ionization (APLPI) are presented. The...     

Radical Addition of Organic Halides to Multiple Bonds in the Synthesis of Heterocyclic Compounds. (Review)

The addition of polyhalides to multiple bonds in the synthesis of various heterocyclic compounds is discussed.