Chromium(II) chloride reduction of α,β-unsaturated nitroalkenes. a facile route to carbonyl compounds.

α,β-Unsaturated nitroalkenes are readily reduced by chromium(II) chloride to the corresponding carbonyl compounds in good yields.     

An efficient and facile one-pot synthesis of cyanohydrin esters from carbonyl compounds catalyzed by iron(III) chloride

A variety of cyanohydrin esters were readily prepared from carbonyl compounds with trimethylsilyl cyanide and acid anhydride under the influence of a catalytic amount of iron(III) chloride in a convenient one-pot procedure.     

Catalytic radical addition of carbonyl compounds to alkenes by Mn(II)/Co(II)/O(2) system

The radical addition of enolizable carbonyl compounds such as malonates and malononitrile to alkenes was successfully achieved through a catalytic process using the Mn(II)/Co(II)/O(2) system to afford the corresponding adducts in fair to good yields. Dimethyl malonate added to 1,5-cyclooctadiene to produce a fused bicycle compound.     

LiAlH4/silica chloride as a new chemoselective system for reduction of carbonyl compounds and phosphine oxides

LiAlH₄/silica chloride system was used as an efficient and chemoselective reductant for organic substrates. The reduction of phosphine oxides was achieved with this system. Good chemoselectivity in reduction of aldehydes and ketones in the presence of other carbonyl compounds was observed.     

Hydrosilylation of carbonyl compounds using a PhSeSiMe(3)/Bu(3)SnH/AIBN system

[reaction: see text] When carbonyl compounds were allowed to react with phenyl trimethylsilyl selenide and tributylstannyl hydride in the presence of a catalytic amount of AIBN as a radical initiator, the hydrosilylation of the carbonyl compounds efficiently proceeded to give the corresponding silyl ethers in moderate to good yields.     

Lewis acid-mediated rearrangement of activated cyclic amines: a facile synthetic protocol for the preparation of amino carbonyl compounds

Ring opening of activated cyclic amines to produce amino carbonyl compounds has been studied in the presence of Lewis acids. Whereas five- and six-membered rings cleave and rearrange via a 1,2-hydride shift, reaction in three- and four-membered rings takes place via a C-C bond migration. In the case of a three-membered ring, a wide variety of Lewis acids proved to be effective for the reaction. Base-induced ring opening of activated alpha,alpha-disubstituted azetidinemethanol and its mechanistic aspects have been studied.     

Phenylselenenyl chloride as a reagent for the facile preparation of cyclic ethers from diolefins

Various cyclic ethers are prepared in good to excellent yields by treating diolefins with phenylselenyl chloride in aqueous acetonitrile. This is the most facile method for organoselenium-induced formation of cyclic ethers from diolefins so far reported.     

Di- and tri-nuclear osmium carbonyl chloride complexes: x-ray structures of Os2(CO)8Cl2 and Os3(CO)12Cl2

Summary Os₂(CO)₈Cl₂ (1) is orthorhombic P2₁2₁2₁ witha=9.3599(9),b=9.879(2),c=16.014(3), V=1480³, D_c=3.03 Mgm^–3 for Z=4. Structure solved by Patterson methods. Final R=0.038, R_w=0.038 [w=(²F)] for 1270 observed reflections and 141 parameters. Os₃(CO)₁₂Cl₂ (2) is monoclinic C2/m witha=12.105(3), b=10.612(3),c=8.798(1) , =117.02(2)°, V=1006³, D_c=3.22 Mgm^–3 for Z=2. Structure solved by Patterson methods. Final R=0.036, R_w=0.037 (w=(²F)^–) for 821 observed reflections and 75 parameters.Complex(1) has an osmium-osmium single bond 2.897(1), with the chloride ligands in equatorial positions,(2) has a linear triosmium chain with osmium-osmium single bonds 2.893(1) and the chloride ligands occupy equatorial sites on the terminal osmium atoms. Both(1) and(2) are isostructural with their osmium carbonyl iodide analogues.     

Reactions between diphenylmethyleneaminolithium Ph2CNLi,and the sulphur-chlorine compounds SCl2, S2Cl2, SOCl2, SO2Cl2 and (NSCl)3

Reactions between diphenylmethyleneaminolithium, Ph₂CNLi, and the chlorides SCl₂, S₂Cl₂, SOCl₂ and SO₂Cl₂ have been used to prepare the compounds (Ph₂CN)₂S, (Ph₂CN)₂S₂, Ph₂CNC(NSO)Ph₂ and (Ph₂CN)₂SO₂ respectively. The disulphide (Ph₂CN)₂S₂ also results from the reaction between Ph₂CNLi and trithiazyltrichloride (NSCl)₃. Features of the IR and mass spectra of these products are discussed, with particular reference to their sulphur-nitrogen bond orders.     

Titanocene(II)-promoted, one-pot, three-component coupling of thioacetals, alkynyl sulfones, and carbonyl compounds: highly stereoselective formation of tert-homopropargyl alcohols

Titanocene alkylidene complexes, generated by desulfurizative titanation of thioacetals with Cp2Ti[P(OEt)3]2, reacted with alkynyl methyl sulfones to produce organotitanium species, which gave tert-homopropargyl alcohols with high diastereoselectivity on treatment with aromatic and alpha,beta-unsaturated ketones.     

Reactions of nitrosyl chloride with [Ni(PPh3)2X2] (X=Cl,Br, NCS or NO3)

Summary Nitrosyl chloride has been treated with [Ni(PPh₃)₂X₂] (X = Cl, Br, NCS or NO₃) to obtain [Ni(PPh₃)XCl]₂ (X=Cl, Br, NCS or NO₃) and [Ni(OPPh₃)(SCN)Cl]₂. The compounds obtained were characterised by analyses, infrared (including far i.r.) and visible spectral studies, magnetic moment and conductivity measurements and many chemical reactions. It is proposed that the compounds have a dimeric structure with a distorted tetrahedral environment around the nickel atom and chloro-bridges.     

Reactions of zinc enolates derived from α,α-dibromo carbonyl compounds with 3-(2-oxo-4a,8a-dihydro-2H-chromene-3-carbonyl)chromen-2-one

Zinc enolates derived from 1-R-2,2-dibromoethanone reacted with 3-(2-oxo-4a,8a-dihydro-2H-chromene-3-carbonyl)chromen-2-one to give the corresponding 1-R-1a-{(1-R-2-oxo-1,7b-dihydrocyclopropa[c]chromen-1(2H)-yl)carbonyl}-1a,7b-dihydrocyclopropa[c]chromen-2(1H]-ones as a single diastereoisomer with cis arrangement of the hydrogen atoms with respect to the cyclopropane ring plane. Reactions of the same electrophilic substrate with zinc enolates obtained from 1-aryl-2,2-dibromoalkanones led to the formation of 1-alkyl-1a-{(1-alkyl-1-aroyl-2-oxo-1,7b-dihydrocyclopropa[c]chromen-1(2H)-yl)carbonyl}-1-aroyl-1a,7b-dihydrocyclopropa[c]chromen-2(1H)-ones as a single diastereoisomer with trans arrangement of the alkyl group and hydrogen atom with respect to the cyclopropane ring plane.     

Structural model of silica nanowire assembled from a highly stable (SiO2)8 unit

The ground-state structures of silica clusters (SiO2)n for n = 1-8 were studied by performing calculations at the B3LYP/6-311+G(d) level of density functional theory. The results indicate that the growth mode of a silica nanowire based on small silica clusters may change at different wire lengths. A linear chain might be assembled from the smallest clusters of rhombic two-membered ring (2MR) with n < or = 5, while the growth motif changes at n = 6 into a more compact form composed of three-membered-rings (3MRs). The 3MR-containing structures become energetically favorable configurations for even longer silica clusters. In particular, the closed molecular ring consisting of 3MRs at n = 8 (i.e., (SiO2)8) with a high symmetry shows extreme energetic stability and relatively high chemical reactivity and thus is considered to be an important building block to assemble into silica nanowires. The relative stability of so-assembled silica nanowires were evaluated and compared with the models of silica nanowires in the literature.     

Synthesis,structures and luminescence of two new Europium(II) Silicate-Chlorides,Eu2SiO3Cl2 and Eu5SiO4Cl6

Eu₂SiO₃Cl₂ and Eu₅SiO₄Cl₆ were prepared by reaction of EuCl₂ with EuSiO₃ and Eu₂SiO₄, respectively, Sr₂SiO₃Cl₂: Eu²⁺ from mixtures of SrCO₃, Eu₂O₃, SrCl₂ · 6H₂O and SiO₂ under reducing conditions. The crystal structures of Eu₂SiO₃Cl₂ [a = 1118.7(5), c = 952.6(1) pm, tetragonal, I4/m, Z = 8, R = 3.3, R_w = 3.0%] and Eu₅SiO₄Cl₆ [a = 900.4(1), b = 1401.7(2), c = 1112.3(2) pm, β = 103.51(1)°, monoclinic, C2/c, Z = 4, R = 3.6, R_w = 2.6%] were determined from four-circle diffractometer data and compared with related compounds. The luminescence properties were investigated at 300 K and at 4.2 K; all compounds show intense bluish-green photoluminescence. Sr₂SiO₃Cl₂:Eu²⁺ shows thermoluminescence.     

Spectrophotometric determination of chloride in PtAl(2)O(3)/SiO(2) catalysts with Hg(SCN)(2)Fe(3+) reagent

A method is described for the determination of chloride in PtAl(2)O(3)/SiO(2) catalysts, based on its extraction with alkali followed by reaction with Hg(SCN)(2)Fe(3+) reagent and spectrophotometric measurement at 460 nm. Beer's law is obeyed in the concentration range 5-75 mug of chloride in 25 ml of aqueous solution. The molar absorptivity is 1.99 x 10(3) l.mole(-1).cm(-1). The rapid colour development, excellent reproducibility and absence of interference from the species most often present in the catalysts are the advantages of the method.     

Clinoptilolite-supported iron(III) nitrate as a powerful and efficient deoximation catalyst. Fast regeneration of carbonyl compounds from oximes

Clinoptilolite-supported iron(III) nitrate (clinofen) ensures fast and efficient regeneration of carbonyl compounds from the corresponding oximes. Published in Russian in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 6, pp. 876–877. The text was submitted by the authors in English.     

Reactions on a surface. 1. Condensation of 3-methyl-3-buten-1-ol with carbonyl compounds on SiO2 and Al2O3

3-Methyl-3-buten-1-ol reacts with various aldehydes and ketones on silica gel and Al₂O₃ surfaces in the absence of solvents and conventional catalysts for this reaction to form derivatives of di- and tetrahydropyrans.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1326–1328, October, 1989.     

X-ray-induced production of gold nanoparticles on a SiO(2)/Si system and in a poly(methyl methacrylate) matrix

Prolonged exposure to X-rays of HAuCl(4) deposited from an aqueous solution onto a SiO(2)/Si substrate or into a poly(methyl methacrylate) (PMMA) matrix induces reduction of the Au(3+) ions to Au(0) and subsequent nucleation to gold nanoclusters as recorded by X-ray photoelectron spectroscopy. The corresponding major oxidation product is determined as chlorine {HAuCl(4)(ads) + X-rays --> Au(ads) + (3/2)Cl(2)(ads) + HCl(ads)}, which is initially adsorbed onto the surface but eventually diffuses out of the system into the vacuum. The reduced gold atoms aggregate (three-dimensionally) into gold nanoclusters as evidenced by the variation in the binding energy during X-ray exposure, which starts as 1.3 eV but approaches a value that is 0.5 eV higher than that of the bulk gold. The disappearance of the oxidation product (Cl2p signal) and the growth of the nanoclusters (related to the measured binding energy difference between the Si2p of the oxide and Au4f of the reduced gold) exhibit first-order kinetics which is approximately 3 times slower than the reduction of Au(3+), indicating that both of the former processes are diffusion controlled. Similarly, gold ions incorporated into PMMA can also be reduced and aggregated to gold nanoclusters using 254 nm deep UV irradiation in air evidenced by UV-vis-NIR absorption spectrocopy.