108-99-6Relevant articles and documents
The first SiHi22+ Complex, Difaydridotetrakis(3-picoline)silicon Dichloride-tetrakis (chloroform)5 [H2Si(3pic)44]Cl2 · CHCl3: Formation chemical equilibria, and structural by NMR spectroscopy and single-crystal X-ray diffraction
Fleischer, Holger,Hensen, Karl,Stumpf, Thorsten
, p. 765 - 771 (1996)
Bis(dichlorosilyl)amine reacts in chloroform solution with 2-picoline to give H3SiCl, H2SiCl2, and HSiCl3 whereas with 3-picoline the two hypervalent silicon compounds H2SiCl2-(3pic)2 and [H2Si(3pic)4]Cl2 ·4 CHCl3 containing hexacoordinated Si atoms are formed. These complexes are in a chemical equilibrium with each other in chloroform solution, from which crystals of [H2Si(3pic)4]Cl2 ·4 CHCl3 could be isolated. The crystal structure of the latter was determined by single-crystal X-ray diffraction. The complex can be regarded as an "contact ion trio" of [H2Si(3pic)4]2+ and two Cl- ions. The N→Si bond lengths, r(Si-N) = 196.9(3} and 197.5(3) pm, are similar to those found in neutral hexacoordinated Si complexes. The data obtained from a 1H1H ROESY experiment suggest that dissolution has no significant impact on the molecular structure of [H2Si(3pic)4]Cl2 ·4 CHCl3. VCH Verlagsgcsellschaft mbH, 1996.
An efficient and chemoselective deoxygenation of hetero cyclic N-oxides using LiCl/NaBH4
Raja Ram,Purushothama Chary,Iyengar
, p. 3511 - 3515 (2000)
A practical and novel reagent system LiCl/NaBH4 is used for the deoxygenation of N-Oxides to amines is described.
Microwave-accelerated direct synthesis of 3-picoline from glycerol through a liquid phase reaction pathway
Luo, Cai-Wu,Feng, Xiao-Yan,Chao, Zi-Sheng
, p. 8863 - 8871 (2016)
A novel route for the synthesis of 3-picoline from glycerol via liquid phase reaction under mild condition, using microwave irradiation, had been well established. The heating mode had a profound effect on the yield of 3-picoline. The formation of 3-picoline could be promoted significantly by microwave heating, however, only very little amount of 3-picoline was generated by conventional heating under the reaction conditions employed in this study. Influencing factors were systemically investigated on the basis of a HAc-catalyzed under microwave irradiation. Additionally, a lot of heterogeneous catalysts were screened. It was found that as high as a 71% yield of 3-picoline was obtained with the mass ratio of pure glycerol/ammonium acetate/acetic acid/TiO2 = 1/3/10/0.2 at 373 K, after only 20 min of microwave irradiation. A catalyst pair (HAc and TiO2) exhibited better catalytic performance relative to other catalysts in this work. Accordingly, microwave assistance together with the catalysts achieved effective transformation of glycerol to 3-picoline under mild conditions. The related plausible reaction mechanisms were also proposed.
In situ formation and reaction of 2-pyridylboronic esters
Fuller, Amelia A.,Hester, Heidi R.,Salo, Eric V.,Stevens, Erland P.
, p. 2935 - 2938 (2003)
2-Pyridylboronic esters were generated by cross-coupling 2-bromopyridines with bis(pinacolato)diboron in the presence of a base and palladium catalyst. The boronic esters reacted in situ with unreacted 2-bromopyridines to afford high yields of 2,2′-bipyridines as homocoupled products. Depending upon the reaction conditions, varying amounts of protodeboronated products were also observed. An attempted cross-coupling between two different 2-bromopyridines produced a nearly statistical mixture of homo- and cross-coupled products.
Effective charge on the nucleophile and leaving group during the stepwise transfer of the triazinyl group between pyridines in aqueous solution
Cullum, Neil R.,Renfrew, A. Hunter M.,Rettura, Donatella,Taylor, John A.,Whitmore, James M. J.,Williams, Andrew
, p. 9200 - 9205 (1995)
Second-order rate constants (kxpy) have been measured for the displacement reaction between substituted pyridines (xpy) and 1′-(2,6-diphenoxy-1,3,5-triazin-2-yl)pyridinium ion in aqueous solution. The rate constants for the reverse reaction (k-xpy) have also been measured for substituted pyridine leaving groups. The plots of log kxpy and log k-xpy against pKaxpy each consist of two intersecting linear correlations consistent with a two-step mechanism involving a Meisenheimer-like intermediate. The overall transfer of the triazin-2-yl group between substituted pyridines has a βeq value of 1.25. There is negligible coupling between the bonding changes in both steps, and the substituent effects indicate that bond formation is half complete in the addition step. Reaction of substituted pyridines with 2,6-diphenoxy-1,3,5-triazin-2-yl chloride has a similar bonding change in the addition step. The 1′-triazin-2-ylpyridinium ion species exist in aqueous solution in equilibrium with the pseudobase formed by addition of water at the 2-position of the pyridinium ring.
Thermal decomposition and ring expansion in 2,4-dimethylpyrrole. Single pulse shock tube and modeling studies
Lifshitz, Assa,Suslensky, Aya,Tamburu, Carmen
, p. 4851 - 4861 (2003)
The thermal decomposition of 2,4-dimethylpyrrole was studied behind reflected shock waves in a pressurized driver single-pulse shock tube over the temperature range 1050-1250 K at overall densities of ～3 × 10-5 mol/cm3. A plethora of decomposition products, both with and without nitrogen, were found in the post-shock mixtures. They were, among the nitrogen containing products: pyridine, two isomers of methylpyrrole, 2-picoline, 5-picoline, HCN, CH3CN, C2H3CN, C2H5CN, and CH≡C-CN. Very small quantities of cis- and trans-CH3CH=CHCN and CH2=CHCH2CN were also found in the post-shock mixtures. Among the products without nitrogen were CH4, C2H4, C2H6, C2H2, CH3H≡CH, CH2=C=CH2, C4H4 and C4H2, and very small quantities of other C4 hydrocarbons and C5 hydrocarbons. The initiation of a chain mechanism in the decomposition of 2,4-dimethylpyrrole takes place via ejection of hydrogen atoms from sp3 carbons and dissociation of the two methyl groups attached to the ring. The H atoms and the methyl radicals initiate a chain mechanism by abstraction of a hydrogen atom from the methyl group and by dissociative recombination of an H atom and removal of a methyl group from the ring. In addition to the dissociation reactions, there are several unimolecular channels that involve ring cleavage. Ring expansion processes that lead to the production of high yields of pyridine and picoline take place from radical species: CH3[C4H2NH]CH2 in the production of picoline and [C4H3NH]CH2 in the production of pyridine. In addition to the chain mechanism, there are unimolecular breakdown processes of the pyrrole ring to yield stable products such as HCN, CH3CN, and others. The total decomposition of 2,4-dimethylpyrrole in terms of a first-order rate constant is given by ktotal = 1016.31 exp(-75.7 × 103/RT) s-1. A reaction scheme containing 36 species and 69 elementary reactions was composed and a computer simulation was performed over the temperature range 1050-1250 K at 25 K intervals. The agreement between the experimental results and the model prediction for most of the species is satisfactory.
Evidence for a Single Transition State in the Transfer of the Phosphoryl Group (-PO32-) to Nitrogen Nucleophiles from Pyridino-N-phosphonates
Bourne, Nicholas,Williams, Andrew
, p. 7591 - 7596 (1984)
The reaction of pyridinio-N-phosphonates with pyridines in aqueous buffers has been demonstrated to involve nucleophilic attack at phosphorus.The second-order rate constants obey the equation log kxpy = 0.15pKxpy - 0.86 for attack on isoquinolino-N-phosphonate over a wide range of pyridine basicity indicating a single transition state; this is consistent with a concerted transfer of the phosphoryl group rather than with a stepwise mechanism involving metaphosphate ion in a ternary encounter complex with donor and acceptor.Transfer of the phosphoryl group to pyridine from substituted pyridinio-N-phosphonates obeys the equation log k = -0.92pKxpy + 5.24 and leads to a βeq of 1.07 for substituent effect on the equilibrium constant for transfer.The effective charge at nitrogen, in the transition state, indicated by these values favors weak P-N bonding.An imbalance of -0.77 effective charge units between entering and leaving nitrogen in the transition state is proposed to derive from the charge on the PO3 atoms, which therefore do not bear a full negative charge in the transition state.Transfer of the phosphoryl group from isoquinolinio-N-phosphonate to amines has been investigated kinetically, and the results are also consistent with weak bonding between phosphorus and nitrogen in the transition state.
Thermal analysis of complexes of cadmium chloride picoline
Liptay, G.,Borbely-Kuszmann, A.,Wadsten, T.,Losonczi, J.
, p. 915 - 922 (1988)
The thermal decomposition of the α, β and γ-picoline complexes of cadmium were studied by means of TG-DTG-DTA. In connection with the preparation of the complex compounds, it was established that the ligand number was influenced by the reaction medium. The thermal decomposition took place stepwise, and intermediates were formed which could be isolated with a derivatograph by the 'freezing-in' method. The structures and properties of these previously unknown compounds were investigated by far-IR spectroscopy and X-ray powder diffraction.
Mild and efficient deoxygenation of amine-N-oxides with BiCl3/Indium system
Yoo, Byung Woo,Choi, Jin Woo
, p. 3550 - 3554 (2009)
The BiCl3/indium system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under mild conditions.
Preparation of pyridine and 3-picoline from acrolein and ammonia with HF/MgZSM-5 catalyst
Zhang, Xian,Wu, Zhen,Liu, Wei,Chao, Zi-Sheng
, p. 10 - 14 (2016)
Pyridine and 3-picoline were prepared from acrolein and ammonia using HF/MgZSM-5 as catalyst. The HF/MgZSM-5 catalyst was produced from modification of HZSM-5 by HF and Mg(NO3)2. It was found that the micropore structure of the HZSM-5 carrier would be destroyed when Mg and HF were loaded. This corrosion process could be promoted by employing HF onto MgZSM-5 carrier comparing with HZSM-5 one, because of the damage of MgO to ZSM-5 stability. A micro-mesoporous HZSM-5 zeolite with fewer and weaker acid sites was prepared after HF modification. Under the optimized conditions, a total yield of 68% can be reached, with 36% being 3-picoline and 30% being pyridine.
