Heavy Ketones Research Articles

Four‐Coordinate Germylene and Stannylene and their Reactivity towards Se & Te**

AbstractIn this work, we have prepared a bulky ligand supported chlorogermylene (LGeCl) [L=C6H4‐2‐{C(Me)=NAr*}; Ar*=(2,6‐bis(diphenylmethyl)‐4‐methylphenyl)] (2), chlorostannylene (LSnCl) (3), four‐coordinate germylene (L2Ge) (4) and four‐coordinate stannylene (L2Sn) (5). Subsequently, the reactions of 4 and 5 with elemental selenium and tellurium led to the isolation of respective heavy ketones (7‐9). All the compounds are well characterized by multinuclear NMR techniques and single‐crystal X‐ray diffraction studies.

Basic Reactivity Pattern of a Cyclic Disilylated Germylene.

In order to estimate the reactivity of disilylated germylene phosphine adducts, a cyclic version of this compound class was reacted with a number of different reagents. Reactions with the chalcogens sulfur, selenium, and tellurium led to dimers of the heavy ketone analogues. Reactions with water and ethyl bromide proceeded to give the respective oxidized germanol and germyl bromide. Two different reactions with alkynes were observed which led either to a germacyclopropene, by addition of tolane to the germylene, or to a silagermacyclobutene, likely formed by addition of the alkyne across a silagermene. Reaction via the silagermene was also observed in the reaction with benzophenone. Reaction of a germylene phosphine adduct with GeCl2·(dioxane) provided insertion of the silylated germylene into a Ge–Cl bond, leading to a germylated chlorogermylene phosphine adduct.

Catalytic pyrolysis of vegetable oils to biofuels: Catalyst functionalities and the role of ketonization on the oxygenate paths

Thermal and catalytic conversions of palm oil were investigated at 693K. The conversions of acetic acid and ethyl acetate in the gas phase were also investigated over the same catalysts as model reactions. The acido-basicity of the catalysts was assessed by IR spectroscopy of adsorbed pyridine. Oxide catalysts slightly decrease the liquid yield, but allow the strong reduction of the production of saponifiable compounds, including fatty acids, in the liquid. The basic catalyst calcined hydrotalcite is the most effective in reducing saponifiables, but produces big amounts of heavy ketones (stearone and palmitone) according to its high activity in acid and ester ketonization. The Lewis acid catalysts alumina (strong) and Na-faujasite (weak) favor decarboxylation reaction, producing hydrocarbon rich liquids with significant amounts of olefins. The Brønsted acid catalyst H-ZSM-5 zeolite produces liquids richest in paraffins with some aromatics. However, the volatility range of the produced liquids is quite broad.

ChemInform Abstract: Kinetic Stabilization of Highly Reactive Species Bearing Heteroatoms

AbstractReview: [60 refs.

Kinetic Stabilization of Highly Reactive Species Bearing Heteroatoms

ABSTRACTBulky substituents, i.e., 2,4,6‐tri‐t‐butylphenyl, 1,1,3,3‐tetramethylindane‐2,2‐diyl, and 2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl, the last of which was developed in our laboratory, were successfully utilized to provide kinetic stabilization to novel types of highly reactive chemical species such as N‐thiosulfinylaniline, thioaldehyde, selenoaldehyde, telluroketone, heavy ketone (a heavier element congener of a ketone), distibene, dibismuthene, disilene, digermene, and silaaromatic compounds (silabenzene and 2‐silanaphthalene). Bowl‐ and capsule‐shaped molecules having a functional group in their cavities were synthesized and applied to the stabilization of highly reactive species such as sulfenic acid, selenenic acid, sulfenyl iodide, nitrosothiol, and a simple enol.

Journey through the Potential Energy Surfaces for the Isomerization and Decomposition Reactions of the Telluroformaldehyde Analogues: H2A═Te and HFA═Te (A = C, Si, and Ge)

The unavailability of monomeric heavy ketone analogues has been ascribed to the evanescence of the very reactive A═E double bond (A and E are the heavier group 14 and group 16 elements, respectively). Can the isolation of any of the monomeric telluro-ketones be assisted by an energetic favorability on its potential energy surface (PES)? In this light, the reaction pathways for the isomerization and decomposition reactions of H2A═Te and HFA═Te (A = C, Si, and Ge) molecules on their singlet state PES have been studied using second-order Møller-Plesset perturbation theory (MP2). The barrier heights reported suggest that telluroformaldehyde, silanetellone, and germatellone are kinetically more resistant to unimolecular reactions than the corresponding lighter chalcogen analogues. However, upon replacing a hydrogen atom by fluorine, the barrier heights of most of the isomerization and decomposition reactions are lowered. Among the unimolecular reactions studied for the H2A═Te and HFA═Te (A = C, Si, and Ge) molecules, the decomposition of cis-FGeTeH into HF and GeTe is found to be the most facile reaction, with a barrier height of only 4.6 kcal/mol. We also predict the ground state telluro-ketones to be viable molecules, as they have no imaginary vibrational frequencies and their lowest vibrational frequencies are always >100 cm(-1). In view of the scarcity of information on the chemistry of the mentioned telluro-ketones, the molecular parameters of various isomers and decomposition products have been reported, and should be useful for future experimental investigations.

Reactivity of germanones: far removed from ketones – a computational study

The recently isolated heavy ketone (X2EO; E = Ge) shows interesting reactivity towards simple addition reactions that are unknown for the organic (EC) ketones. Density Functional Theory (DFT) calculations elucidate the role of the central atom and the substituent effects on the addition of acetone, carbon dioxide and water to formaldehyde, acetone, 2,4-dimethyl-3-pentanone, diphenyl ketone and their heavier (Si, Ge) analogs. NBO analysis reveals a large charge separation for heavier analogs, thereby increasing their reactivity. The activation barriers are reduced by as much as ∼30.0 to 40.0 kcal mol−1 for the nucleophilic addition to the heavy ketones as (E = Si and Ge) compared to those of an organic ketone. Comparably lower stability of the reactants and higher stability of the transition state lowers the barriers of addition reactions for the heavier ketones. Apart from a smaller barrier, the nucleophilic addition reactions which are unfavorable for ketones are favored by 20–40 kcal mol−1 for their silicon and germanium counterparts. Calculations predict that similar addition reactions must be feasible for silanones (X2SiO) as well.

A stable germanone as the first isolated heavy ketone with a terminal oxygen atom

The carbon-oxygen double bond of ketones (R(2)C=O) makes them among the most important organic compounds, but their homologues, heavy ketones with an E=O double bond (E=Si, Ge, Sn or Pb), had not been isolated as stable compounds. Their unavailability as monomeric molecules is ascribed to their high tendency for intermolecular oligomerization or polymerization via opening of the E=O double bond. Can such an intermolecular process be inhibited by bulky protecting groups? We now report that it can, with the first isolation of a monomeric germanium ketone analogue (Eind)(2)Ge=O (Eind=1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl), stabilized by appropriately designed bulky Eind groups, with a planar tricoordinate germanium atom. Computational studies and chemical reactions suggest the Ge=O double bond is highly polarized with a contribution of a charge-separated form (Eind)(2)Ge(+)-O(-). The germanone thus exhibits unique reactivities that are not observed with ordinary ketones, including the spontaneous trapping of CO(2) gas to provide a cyclic addition product.

Multiply Bonded Germanium, Tin and Lead Compounds

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Kinetically Stabilized Silaneselone and Silanetellone

Abstract Kinetically stabilized silaneselone [Tbt(Dip)Si=Se (4); Tbt=2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Dip=2,6-diisopropylphenyl] and silanetellone [Tbt(Dip)Si=Te] were synthesized by direct chalcogenation of Tbt(Dip)M: (M=Si, Ge) with elemental chalcogen. Deselenation of Tbt(Dip)SiSe2 also gave 4. Metallanetellones [Tbt(Dip)M=Te; M=Si, Ge] were also synthesized by the reaction of Tbt(Dip)MLi2 (M=Si, Ge) with TeCl2, which is a new synthetic method for heavy ketones.

Heavy ketones, the heavier element congeners of a ketone.

In contrast to ketones, one of the most important classes of organic compounds, their heavier element congeners, "heavy ketones", are much less explored because of their extremely high reactivities. This Account reviews the synthesis, reactivities, and structures of stable heavy ketones containing silicon, germanium, and tin as well as those of moderately stable lead analogues. These heavy ketones are kinetically stabilized by taking advantage of bulky substituents, yet they can undergo a variety of reactions due to the intrinsic high reactivity of heavier group 14-16 double bonds. Systematic comparisons for silicon through lead compounds reveal interesting differences in their properties, depending on the elements.

The Chemistry of Germanium-Containing Heavy Ketones

Abstract The recent applications of an extremely bulky and efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (denoted as Tbt in this article), to the kinetic stabilization of a series of doubly bonded compounds between germanium and heavier chalcogen atoms (we coin the expression “germanium-containing heavy ketones” for this family of heavier congeners of germanone) are described. Combination of a Tbt group with some other bulky aromatic or alkyl substituent enabled us to synthesize the novel germanium-containing double-bond species [Tbt(R)Ge=X; R = 2,4,6-triisopropylphenyl (Tip) or bis(trimethylsilyl)methyl (Dis)] such as germanethiones (X = S), germaneselones (X = Se), and germanetellones (X = Te) as stable crystalline compounds, while the germanone [Tbt(Tip)Ge=O], the most reactive species among the germanium-containing heavy ketones, was found to be very difficult to isolate and was evidenced only by the trapping reactions. The X-ray crystallographic analysis of the isolated germanium-containing heavy ketones revealed a completely trigonal planar geometry around their germachalcogenocarbonyl units and their ideally doubly bonded character, which was also confirmed by their spectroscopic data.

New Aspects in the Chemistry of “Heavy Ketones”: Stable Metallaneselones and Metallanetellones

Stable metallaneselones and metallanetellones [Tbt(R)M=X; M = Si, Ge, Sn, X = Se and Te],, i.e., a new family of double-bond compounds between heavier group 14 elements and chalcogen atoms (“heavy ketones”), are synthesized by taking advantage of kinetic stabilization using an extremely bulky and efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (denoted as Tbt). The molecular structures and chemical properties of these new double-bond species are also described.

ChemInform Abstract: New Progress in the Chemistry of Multiple‐Bond Compounds of Heavier Typical Elements: In Pursuit of the “Heavy Ketones”

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

高周期典型元素多重結合化合物の化学の新展開：『重いケトン』を求めて

Recent studies on the synthesis, structure, and reactivity of kinetically stabilized double-bond compounds between group 14 metals (M=Si, Ge, and Sn) and heavier chalcogens such as sulfur or selenium are reviewed. Three different approaches for the formation of “heavy ketones” were examined, i. e., (i) the thermal retrocycloaddition of 1, 2, 4, 3-trichalcogenametallolanes bearing a new steric protection group, 2, 4, 6-tris- [bis (trimethylsilyl) methyl] phenyl (denoted as Tb), (ii) the reactions of kinetically stabilized divalent group 14 metal species, Tb (Ar) M, with an epichalcogenide or elemental chalcogen, and (iii) the dechalcogenation reactions of 1, 2, 3, 4, 5-tetrachalcogenametallolanes, Tb (Ar) MY4 (Y=, S, Se). As a result of kinetic stabilization by the combination of Tb and 2, 4, 6- triisopropylphenyl (Tip) group, silanethione Tb (Tip) Si S and germanethione Tb (Tip) Ge=S were successfully isolated as monomeric and stable crystalline compounds, while the corresponding stannanethione Tb (Tip) Sn = S was synthesized as a monomeric species stable in solution, Of particular note is the X-ray crystallographic structure analysis of germanethione, which revealed the completely trigonal planar geometry for the germathiocarbonyl unit and the remarkable bond shortening for the Ge-S double bond.