Formation of π-Allyl Palladium Complexes from Tertiary Alcohols

Reactions of 2-methyl-2-propanol, 2-methyl-2-butanol, 2-methyl-2-pentanol, 1-methyl-1-cyclohexanol, and 1-ethyl-1-cyclohexanol with palladium(II) tetraaqua complex in a perchloric acid medium give carbonyl and aromatic compounds, as well as the corresponding palladium -allyl complexes. The complexes were isolated from the reaction mixtures by way of formation of 2,2'-bipyridine complexes and characterized by the elemental analyses and ¹H and ¹³C NMR spectra. The main direction of transformation of acyclic alcohols is formation of complexes with no alkyl substituents at the central carbon atom of the allyl ligand; with cyclic alcohols, exocyclic complexes are formed.     

Reactions of Tertiary Alcohols with Palladium(II) Tetraaqua Complex. Formation of Palladium π-Allyl Complexes

Transformations of 2-methyl-2-propanol, 2-methyl-2-butanol, 2-methyl-2-pentanol, 1-methyl-1-cyclohexanol, and 1-ethyl-1-cyclohexanol in the presence of tetraaquapalladium(II) ions in perchloric acid madium were studied. It was found that the reactions give rise to palladium(II) -allyl complexes. The reaction rate increases and the yield of the corresponding -allyl complex decreases with increasing hydrocarbon chain length. Addition of iron(III) ions to the systems essentially increases the yield of palladium -allyl complexes. The olefin formed from the corresponding tertiary alcohol participates in the formation of the palladium -allyl complex. Oxidation of 2-methyl-2-butanol with tetraaquapalladium(II) ions gives the isomeric palladium -allyl complexes [Pd(³-(CH₃)₂CCHCH₂)bpy]ClO₄ and [Pd(³-(CH₂C(CH₃)CHCH₃))bpy]ClO₄, which were isolated using 2,2'-bipyridyl and characterized by ¹H and ¹³C NMR spectroscopy.     

Synthesis and structure of penta-platinum σ-bonded derivatives of corannulene

The synthesis of a new class of Pt(II) complexes with corannulene by way of either oxidative addition or reductive coupling is reported and their crystal structures are investigated. The crystal structure for {trans-Pt(PEt₃)₂Cl}₄{cis-Pt(PEt₃)₂Cl}C₂₀H₅ (1) consists of two enantiomers in a unit cell and shows cis- and trans-configuration around Pt(II) due to bulky PEt₃ ligands. The pentanuclear Pt(II) complex, 1, readily reacts with 1-ethynyl-4-nitrobenzene to afford the penta-alkynyl substituted Pt(II) complex (2). Although there are still bulky PEt₃ ligands around the Pt atoms in 2, all five Pt(II) have trans-configurations. The bowl of corannulene in 2 is shallower than that of 1. Therefore, the bowl depth of corannulene plays a key role in the determination of molecular geometry of σ-bonded pentanuclear complexes bearing corannulene.     

Samarium(II) Diiodide Induced Polarity Inversion of π-Allyl Palladium Complexes: The Formation of Allylic Selenides

As a versatile one-electron transfer reducing and coupling agent, samarium diiodide has been extensively used in organic synthesis in last decade. It has been reported that electrophilic p-allyl palladium complexes could undergo polarity inversion to nucleophilic species with the aid of SmI2, and could trap some electrophiles1. It is well known that allylic selenides are rather important intermediates in organic synthesis. They have been recognized as useful synthons of allylic anion stabi…     

Rapid Synthesis of π-Phenylglycine by Carboxylation of π-Lithiobenzylisocyanide

An expanding field of interest in nuclear medicine is the preparation of radiopharmaceuticals labelled with cyclorrn produced isotopes of short half life.^1–3 In an investigation to prepare ¹¹C-labelled amino acids we developed a new and repid synthesis for the preparation of a-phenylglycine. The preparation of other amino acids by this route is under investigation. α-Lithiobenzylisocyande⁴ was treated with carbondioxyde and the intermediate was hydrolysed to the amino acid. The overall yield (75–808) was accomplished in 50–70 minutes.⁺     

Samarium （Ⅱ） Diiodide Induced Polarity Inversion of π—Allyl Palladium Complexes：The Formation of Allylic Selenides

Allylic acetates were reduced with Pd(O)-Sml2 in the presence of ArsCbR to from corresponding allylic selenides in good yields.     

Epoxide as an aldehyde equivalent in allyl-transfer reaction with γ-adduct of homoallylic alcohol (allyl donor) giving α-adduct of homoallylic alcohol

Acid-catalyzed reactions of epoxides 2 with homoallylic alcohol γ-adducts, 1 [Me₂C(OH)CHRCHCH₂], afford homoallylic alcohol α-adducts 3-5 via allyl-transfer reaction, sometimes being more effective than those using the corresponding aldehydes.     

Bio-regeneration of π-complexation desulfurization adsorbents

The coupling of adsorption desulfurization and biodesulfurization is a new approach to produce clean fuels. Sulfur compounds are firstly adsorbed on adsorbents, and then the adsorbents are regenerated by microbial conversion. п-Complexation adsorbent, Cu(l)-Γ, was obtained by ion exchanging Γ-type zeolite with Cu²⁺ and then by auto-reduction in helium at 450°C for 3 h. Dibenzothiophene (DBT) was used as a model compound. The effects of cell concentration, volume of oil phase, the ratio of aqueous phase to adsorbent on DBT desorption by a bacterium were studied. The amounts of DBT desorbed and 2-HBP produced can be apparently increased with addition of n-octane. BDS activity can be improved by increasing cell concentration and the ratio of water-to-adsorbent. 89% of DBT desorbed from the adsorbents can be converted to 2-HBP within 6 h and almost 100% within 24 h, when the volume ratio of oil-to-water was 1/5 mL/mL, the cell concentration was 60 g·L^-1, and the ratio of adsorbent-to-oil was 0.03 g- mL^-1. The amount of 2-HBP produced was strongly dependent on the volume ratio of oil-to-water, cell concentration and amount of adsorbent. Adsorption capacity of the regenerated adsorbent is 95% that of the fresh one after being desorbed with Pseudomonas delafieldii R-8, washed with n-octane, dried at 100°C for 24 h and auto-reduced in He.     

Synthetic Applications of π-Electron-Deficient Sulfones

Abstract

The use of π-electron-deficient aryl sulfones, especially 3,5-bis(trifluoromethyl) phenyl alkyl sulfones (BTFP-sulfones) as soft nucleophiles, as caboxylic acid protecting group and in Julia–Kocienski olefination reactions is described. In the case of α-(arylsulfonyl)acetates dialkylation, reactions are performed under phase-transfer analysis (PTC) conditions using K ₂ CO ₃ as base. Esters derived from 2-(arylsulfonyl)ethanol can be deprotected using aqueous NaHCO ₃ . Alkyl BTFP sulfones are coupled with carbonyl compounds using KOH or P4-t-Bu as bases to give the corresponding alkenes after Smiles rearrangement.     

C-acylation of π-rich heterocycles byo-chlorobenzenesulfonylisocyanate

Nitrogen-containing -rich heterocycles under mild conditions are acylated by o-chlorobenzene-sulfonylisocyanate, forming C-arylsulfonylcarbamoyl derivatives; O- and S-containing heterocycles do not react under these conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 205–209, February, 1996.     

Electrocatalytic Oxidation of Ethanol on Electrodcposited Palladium Electrode

Therearemanyinvestigationsabouttheelectrocatalyticoxldationofethanolontheelectrodeofplatinunlelectrode'-'.whicharemainlyinacidmedium.However.tothebestknowledgeoftheauthor.therearenoinvestigationsabouttheoxidatiollofethanolonpalladiumelectrode.letaloneonPd/GCelectrodepreparedbyelectrodeposition.Accordingtotheexperimentalresultsinthispaper,Pd/GCelectrodeismoreelectroactivetotheoxidationofethanolthantothatofmethanolinalkalinemedium(e.g.inI.0mol/LNaOH).basedontheiroxidationpeakpotentialswhicha…     

Energies of π*- and π-states of the conduction band and valence band of chiral carbon nanotubes

Nanotubes (NTs) are mainly represented by (n,p) chiral NTs with chirality indices 0 < p < n delimited by (n,0) and (n,n) for achiral NTs. In (n,p) chiral NTs, the unit cell hexagons have a helical arrangement on the cylindrical surface of an NT and common angular and axial translations. An analytical formula was derived for calculation of the band structure of both chiral and achiral NTs with chirality indices 0 ≤ p ≤ n and band diagrams of some chiral NTs. Chiral NTs significantly extend the range of semiconducting NTs. An equation for the band gap width ΔЕ of semiconducting chiral and achiral NTs was derived: \(\frac{{\vartriangle E}}{{{\gamma _0}}} = \frac{{2\pi }}{{\sqrt {3{n^2} + 3np + 3{p^2}} }}\). Tables of the band structure parameters of metallic and semiconducting chiral NTs are presented.     

Electronic structure and aromaticity of planar singlet π-electron monocyclic π2 carbenes

Induced -electron ring currents and relative diamagnetic susceptibilities of planar singlet -electron monocyclic ² carbenes are calculated in the coupled variant of perturbation theory in the CNO method. It is shown that the parity theorem holds for charged planar ² and ² carbenes formally generated by the detachment of a proton or a hydride ion from alternant hydrocarbons. This leads, in such carbenes, to the same energies of singlet-singlet and singlet-triplet transitions, electric polarizabilities, conjugation energies, -electron ring currents, diamagnetic susceptibilities and current contributions to chemical shifts, whereas the charge contributions to the latter are of opposite signs.Donbas State Academy of Building and Architecture, 1 Derzhavina St., 339023 Makeevka, Donetsk Region, Ukraine. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 3, pp. 157–162, May–June, 1996. Original article submitted December 5, 1994.     

Volume-conserved Twist Excited-state of π-Conjugated Molecules

The excited state characters of HY103 have been studied by means of time-resolved photon emission (time-correlated single photon counting) and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normal fluorescence state, and a weak fluorescence emission around 670 nm. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted (VCT) state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of ?-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of ?-conjugated molecules in restricted environment is complex.     

Charge-transfer complexes of benzanilides with π-acceptors

Spectrophotometric studies of several substituted benzanilides as electron donors with tetracyanoethylene (TCNE) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as electron acceptors have given results that are consistent with an interpretation of 1:1 charge-transfer (CT) complexes. The nature of interaction as well as the substituent effects on the CT complexation are discussed.     

Efficient syntheses of π-electron deficient macrocycles

ABSTRACT

Cyclobis(paraquat-p-phenylene) (CBPQT⁴⁺) cyclophane represents an ideal π-electron deficient macrocycles, which demonstrates the extraordinary ability of hosting a variety of π-electron-rich guests in its rigid, preorganised cavity. However, this macrocycle undergoes large ring strain and therefore its preparation is often low yielding. In order to increase its yields, high-dilution conditions and template-directed synthesis are employed, which are rather time-consuming, i.e. a few weeks including template removal. Herein, we attempt to solve these problems by either using click reaction, or decreasing the ring strain by using a flexible linker. Three analogues of CBPQT⁴⁺ ring were synthesised without the need of guest template, each of which contains two bipyridinium units. Two of these three macrocycles are able to recognise π-electron rich guests within their cavities. However, the one obtained via click reaction demonstrates low guest recognition ability.     

Interpolation of shared π-bonds in cyclofusene

Cyclofusene is a corona-condensed benzenoid whose graph-theoretic representation consists of hexacycles with exactly two non-adjacent shared II-bonds. We showed that the number of linear chains, k, is an upper bound for m, the number of shared II-bonds. Furthermore, this upper bound is achievable. In this paper, we show that given a positive even integer m < k, there exists m shared II-bonds. In other words, the number of shared II-bonds in cyclofusene has the even interpolation property.     

Sorption–Spectrometric Determination of Palladium in Chloride Solutions

A sorption–spectrometric method was developed for the determination of palladium in solutions of complex composition using cellulose filters impregnated with trioctylamine with the subsequent formation of the colored compound of palladium with 4-(2-pyridylazo)resorcinol on the filter. It was demonstrated that conditions for the preconcentration of palladium coincide with conditions for the formation of colored compounds (green and red forms of palladium complexes) in the sorbent phase. The highest selectivity is observed for the formation of the green form; in this case, the determination of palladium is not affected by the interference from large amounts of concomitant elements (macrocomponents of ores). Palladium was determined on filters by diffuse reflectance spectrometry with the calculation of chromaticity characteristics and by a test scale. The detection limits were 0.5 (green form) and 0.3 (red form) g of palladium on the filter. High precision of results of the determination of palladium (RSD < 5%) is attained in a wide range of its concentrations.