14679-13-1Relevant academic research and scientific papers
A novel and efficient method for the preparation of unstable tetramethylzirconium and its application using a microflow system
Uehata, Koji,Nishida, Mayumi,Nishida, Atsushi
, p. 73 - 75 (2012)
We have developed a novel and efficient method for the preparation of unstable tetramethylzirconium and its application to the synthesis of tetrakis(N-methylethylamido)zirconium and dimethylbis(indenyl)zirconium using a microflow system.
Non-catalytic conversion of C-F bonds of benzotrifluorides to C-C bonds using organoaluminium reagents
Terao, Jun,Nakamura, Misaki,Kambe, Nobuaki
supporting information; experimental part, p. 6011 - 6013 (2010/11/16)
A facile method for the conversion of C-F bonds of benzotrifluorides to C-C bonds has been developed using aluminium reagents in the absence of catalysts.
Suzuki cross-coupling reactions between alkenylboronic acids and aryl bromides catalysed by a tetraphosphane-palladium catalyst
Peyroux, Eugenie,Berthiol, Florian,Doucet, Henri,Santelli, Maurice
, p. 1075 - 1082 (2007/10/03)
A range of alkenylboronic acids undergo Suzuki cross-coupling with aryl bromides in good yields in the presence of [PdCl(C3H 5)]2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphanyl) methyl]cyclopentane as a catalyst. A wide variety of 1-arylprop-1-enes, 2-arylprop-1-enes, 2-arylbut-1-enes and 1,1-diarylethylene or styrene derivatives have been prepared. Moreover, the reaction tolerates several functions, such as acetyl, formyl, nitrile or nitro. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
SOLVENTS CONTAINING CYCLOALKYL ALKYL ETHERS AND PROCESS FOR PRODUCTION OF THE ETHERS
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Page 19, (2008/06/13)
The present inventions are (A) a solvent comprising at least one cycloalkyl alkyl ether (1) represented by the general formula: R1-O-R2 (wherein R1 is cyclopentyl or the like; and R2 is C1-10 alkyl or the like); (B) a method of preparations the ethers (1) characterized by reacting an alicyclic olefin with an alcohol in the presence of an acid ion-exchange resin having a water content of 5 wt% or less. The solvent is useful as cleaning solvent for electronic components, precision machinery components or the like, reaction solvent using various chemical reactions, extraction solvent for extracting objective organic substances, solvent or remover for electronic and electrical materials, and so on. The process enables industrially advantageous production of the objective cycloalkyl alkyl ethers (1).
How does organic structure determine organic reactivity? The effect of ortho-dimethyl groups on the nucleophilic substitution and alkene-forming elimination reactions of ring-substituted cumyl derivatives
Amyes, Tina L.,Mizerski, Tadeusz,Richard, John P.
, p. 922 - 933 (2007/10/03)
The addition of a pair of ortho-methyl groups to ring-substituted cumyl derivatives to give the corresponding 2,6-dimethylcumyl derivatives X-1-Y leads to modest (5-fold) changes in the observed rate constant for reaction in 50:50 (v:v) trifluoroethanol-
Ortho Methyl Group Effects in Cumyl Systems
Timberlake, Jack W.,Pan, Dawei,Murray, Jane,Jursic, Branko S.,Chen, Tonghua
, p. 5295 - 5298 (2007/10/02)
In an attempt to evaluate the steric effect of ortho methyl groups on the stability of the cumyl radical, 2,2',4,4',6,6'-hexamethylazocumene (6) was synthesized and its rate of decomposition was measured.The fact that 6 decomposes 40 times faster than azocumene is attributed to a ground state steric effect.Calculations on the mesitylcumyl radical 1 and cation 2 show both systems to be substantially nonplanar with dihedral angles of 48 deg and 35 deg, respectively.Calculated charge distributions for cation 2 corroborate previously obtained NMR results which showed substantial loss of charge delocalization.
THE EFFECT OF ORTHO METHYL GROUPS ON CUMYL SYSTEMS
Evilia, Ronald F.,Pan, Dawei,Timberlake, Jack W.,Whittenburg, Scott L.
, p. 871 - 874 (2007/10/02)
The reactions of 2-mesityl-2-propanol (2) and 2-mesityl-1-propene (6) have been investigated with the objective of evaluating the effect of ortho methyl groups on chemical reactivity.The 13C NMR spectrum of 2-mesityl-2-propyl cation (3) indicates the expected steric inhibition to resonance.
Ketone methylenation using the Tebbe and Wittig reagents - A comparison
Pine,Shen,Hoang
, p. 165 - 167 (2007/10/02)
Ketone methylenation has been accomplished using the Tebbe and the Wittig reagents. Comparison of the two reagents for a variety of ketones shows that the Tebbe reagent gives better product yields than the Wittig reagent. This is particularly important when the ketone substrate is hindered. It is also noted that the Tebbe reaction accomplishes methylenation in a non-basic medium, thus racemization does not take place on substrates with enolizable chiral centers.
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.
