4674-23-1Relevant articles and documents
A kind of preparation 2, the 2 [...], 4,4 the [...], 6,6 the joint animal pen[...] -six method for a base
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Paragraph 0022; 0023, (2016/10/07)
The invention relates to a method for preparing 2,2',4,4',6,6'-hexamethyl bibenzyl. The method comprises the following steps: by taking 1,3,5-trimethylbenzene as a raw material, reacting with 1,2-dichloroethane under the action of a catalyst, to obtain a
Facile reductive coupling of benzylic halides with ferrous oxalate dihydrate
Khurana, Jitender M.,Chauhan, Sushma,Maikap, Golak C.
, p. 1737 - 1740 (2007/10/03)
Facile reductive coupling of benzylic halides is reported with ferrous oxalate dihydrate in DMF or HMPA under nitrogen atmosphere at 155-160°C. The coupling is proposed to proceed by two successive oxidative additions of benzylic halides to ferrous oxalate to give an intermediate organoiron complex which undergoes concerted dimerization to give the corresponding reductively coupled dimers in high yields.
Orthoamides, LIX [1]. Formyl-aalen [tris(diformylamino)methane] - A new formylating reagent for activated aromatic compounds
Kantlehner, Willi,Haug, Erwin,Scherr, Oliver,Ziegler, Georg
, p. 1295 - 1304 (2007/10/03)
In the presence of strong Lewis acids such as aluminum chloride or boron trichloride, formyl-aalen [tris(diformylamino)methane] (3) acts as a formylating reagent for aromatic alkane compounds and aromatic ethers. The orthoamide 3 delivers three formyl groups for the formylation process. Thus toluene, cumene, tert-butylbenzene, hexylbenzene, o-xylene, p-cymene, biphenyl, anisole, diphenylether and 1,3-dimethoxybenzene can be formylated in 1,2-dichloroethane. In these reactions, 3 and aluminum chloride should be used in a molar ratio of 1:6 to 1:9.
Synthesis, reactions, and structural and NMR features of [2.2]metacyclophane monoenes and their tricarbonylchromium and cyclopentadienyliron(+) complexes
Mitchell, Reginald H.,Zhang, Limin
, p. 7140 - 7152 (2007/10/03)
8,16-Dimethyl-, 5,8,13,16-tetramethyl-, and 4,6,8,12,14,16- hexamethyl[2.2]metacyclophanene have been synthesized from the corresponding methyl-substituted 3-thia[3.2]metacyclophane precursors via a Wittig rearrangement-Hofmann elimination procedure. Simp
Photochemistry of α-(o-tolyl)acetone and some derivatives: Triplet α-cleavage and singlet δ-hydrogen abstraction
Noh, Taehee,Lei, Xue-Gong,Turro, Nicholas J.
, p. 3105 - 3110 (2007/10/02)
Photolysis of α-(o-tolyl)acetone (TA) in 2-propanol was reported not to produce the indanol product expected from δ-hydrogen abstraction and cyclization of the resulting 1,5-biradical. A reinvestigation of this reaction reveals that the photolysis of solutions of TA does produce an indanol, albeit as a minor product. Similarly, photolysis of benzene solutions of o-tolylmethyl benzyl ketone (TBK) and o-tolylmethyl cyclohexyl ketone (TCK) results in the formation of indanols as minor products (ca. 5-10%). However, the photolysis of mesitylmethyl benzyl ketone (MBK) yields an indanol in significant yield (ca. 40%). In all cases, the diphenylethanes (DPEs) expected from free-radical recombination of benzylic radicals produced by α-cleavage are produced as dominant products. In order to determine the synthetic limitations of indanol formation from the photolysis of α-(o-tolyl)acetones, the mechanism of these photolyses was investigated. Sensitization with triplet acetone generated from the thermolysis of tetramethyl-1,2-dioxetane at 70 °C, quenching of the disappearance of ketone by isoprene, and isoprene quenching of the formation of indanol and fluorescence demonstrate that α-cleavage occurs dominantly from the triplet state and that δ-hydrogen abstraction occurs exclusively from the singlet state. Rates of quenching of acetone phosphorescence by dibenzyl ketone (DBK) and TBK in acetonitrile are found to be about 1 order of magnitude less than the rate of diffusion control. The yield of indanol can be enhanced by the introduction of methyl groups to the aryl ring, an increase in the reaction temperature, the addition of a triplet quencher to the reaction mixture, and, as previously reported, the use of microheterogeneous media. The quantum yield measurements for product formation show that the efficiency of α-cleavage drops by half from DBK to TBK and by a factor of 3 from TBK to MBK. We interpret this inefficiency to result from a radiationless deactivation of the singlet state which occurs when the o-tolyl group is attached to the α-position of a dialkyl ketone and this radiationless transition is induced by an incipient but incomplete δ-hydrogen abstraction, as previously proposed for γ-hydrogen abstraction.
N-NITRENES III. THE CAGE EFFECT AND THE FORMATION OF CROSSED PRODUCTS IN THE DISSOCIATION OF DI(ARYLMETHYL)AMINONITRENES
Savin, V. I.
, p. 29 - 34 (2007/10/02)
Symmetrically and unsymmetrically substituted di(arylmethyl)aminonitrenes, generated by thermolysis of the potassium salts of the respective methanesulfonohydrazides, dissociate in methanol, cyclohexanol, and dimethyl sulfoxide with the formation of nitrogen, 1,2-diarylethanes, and diarylmethanes.Unsymmetrically substituted di(arylmethyl)aminonitrenes form the products from crossed coupling of the arylmethyl radicals.The magnitude of the cage effect was determined for the pair of arylmethyl radicals, and the effect of the viscosity of the solvent on the yield of the cage recombination product was investigated.
NITRENES. SYNTHESIS OF UNSYMMETRICAL BIBENZYLS
Savin, V. I.
, p. 35 - 41 (2007/10/02)
A method was developed for the synthesis of unsymmetrical bibenzyls by thermolysis of the potassium salts of methanesulfonohydrazides in dimethyl sulfoxide in the presence of 1-pentanethiol.The yields of the unsymmetrical bibenzyls and their derivatives c
Diverse photochemistry of sterically congested α-arylacetophenones: ground-state conformational control of reactivity
Wagner, Peter J.,Zhou, Boli,Hasegawa, Tadashi,Ward, Donald L.
, p. 9640 - 9654 (2007/10/02)
The effects of α and ortho substituents on the photoreactivity of various α-(o-tolyl)- and α-mesitylacetophenones have been measured. In general, both types of substitution lower the efficiency of cyclization to 2-indanol derivatives in solution. 1,3-Rearrangement of an α-mesityl group to group to form enol ethers and α-cleavage to radicals compete to various degrees, in some cases becoming dominant. Quenching studies in solution show that all three reactions occur from the same n,π* triplet state; α-substitution lowers rate constants for δ-hydrogen abstraction and increases those for α-cleavage and 1,3-rearrangement. X-ray crystal analysis and MMX calculations both show that any additional substitution at the α-carbon of α-aryl (phenyl, tolyl, or mesityl) ketones favors conformers in which the α-aryl group have rotated 120° away from eclipsing the carbonyl. In agreement with this, α-phenyl and α-(o-tolyl) ketones undergo γ-hydrogen abstraction (Norrish type II reaction) with rate constants almost as large as those of the nonarylated ketones. NMR line-broadening studies show that, in most of the α-mesityl ketones, the rate constants for rotation around the mesityl-α-carbon bond (104-106 s-1) are much slower than triplet decay. The same is true for rotations around the carbonyl-α-carbon bond in the α-arylisobutyrophenones. Considered of the spectroscopic evidence, triplet lifetimes, and calculated rotational barriers indicates that ground-state conformational preferences determine which excited-state reactions can occur in most of these ketones. Many of the ketones that cyclize in low yield in solution do so in much higher yield when irradiated as solids, presumably because α-cleavage to radicals becomes mostly revertible. The solid-state reactivity demonstrates that hydrogen abstraction can occur from what are supposedly nonideal geometries; in particular, large values (60-70°) for the dihedral angle and rate constants for hydrogen abstraction in solution plane of the carbonyl π system. The relationship between this angle and rate constants for hydrogen abstraction in solution is discussed. Rate constants for α-cleavage reveal the separate influences of steric congestion and conjugation of the developing benzyl radicals. The 1,3-aryl migration to oxygen appears to arise from initial CT complexation of the α-aryl to the carbonyl; subsequent bonding of oxygen to the benzene ring apparently relieves steric congestion. The 50:50 initial mixture of Z and E enol ethers suggests that the rearrangement is adiabatic, generating enol ether in its twisted triplet state. A large enhancement of indanol yields by alcoholic solvents is suggested to involve protonation of the same CT complex.
Conformational control of photoreactivity: Three α-mesityl ketones that undergo efficient radical cleavage
Wagner,Zhou
, p. 2251 - 2254 (2007/10/02)
α-Mesitylisobutyropohenone, 1,2-dimesitylethanone, and 2-phenyl-1,2-dimesitylethanone all undergo only one photoreaction in solution, α-cleavage to acyl radicals. Quantum yields are all over 0.30 and triplet rate constants are ≥5 x 108 s-1. In each case, bond rotations are so slow that reaction occurs from the preferred ground state geometries, which hold the molecules in conformations ideal for cleavage. The large cleavage rate constants reflect relief of steric strin as well as ideal orientation of π and σ orbitals.
Application of Empirical Force Field Calculations to Internal Dynamics in 9-Benzyltriptycenes
Nachbar, Robert B.,Hounshell, Douglas W.,Naman, Vincent A.,Wennerstroem, Olof,Guenzi, Alberto,Mislow, Kurt
, p. 1227 - 1232 (2007/10/02)
Conformational maps for internal rotation in 9-benzyltriptycene (1), 9-(2,6-dimethylbenzyl)triptycene (2), and 1-methyl-9-(2,6-dimethylbenzyl)triptycene (6) have been calculated by the empirical force field (EFF) method and the results compared with varia
