- Interconversion of nicotine enantiomers during heating and implications for smoke from combustible cigarettes, heated tobacco products, and electronic cigarettes
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Physiological properties of (R)-nicotine have differences compared with (S)-nicotine, and the subject of (S)- and (R)-nicotine ratio in smoking or vaping related items is of considerable interest. A Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) method for the analysis of (S)- and (R)-nicotine has been developed and applied to samples of nicotine from different sources, nicotine pyrolyzates, several types of tobacco, smoke from combustible cigarettes, smoke from heated tobacco products, e-liquids, and particulate matter obtained from e-cigarettes aerosol. The separation was achieved on a Chiracel OJ-3 column, 250 × 4.6 mm with 3-μm particles using a nonaqueous mobile phase. The detection was performed using atmospheric pressure chemical ionization (APCI) in positive mode. The only transition measured for the analysis of nicotine was 163.1 → 84.0. The method has been summarily validated. For the analysis, the samples of tobacco and smoke from combustible cigarettes were subject to a cleanup procedure using solid phase extraction (SPE). It was demonstrated that nicotine upon heating above 450°C for several minutes starts decomposing, and some formation of (R)-enantiomer from a sample of 99% (S)-nicotine is observed. An analogous process takes place when a 99% (R)-nicotine is heated and forms low levels of (S)-nicotine. This interconversion has the effect of slightly increasing the content of (R)-nicotine in smoke compared with the level in tobacco for combustible cigarettes and for heated tobacco products. The (S)/(R) ratio of nicotine enantiomers in e-liquids was identical with the ratio for the particulate phase of aerosols generated by e-cigarette vaping.
- Moldoveanu, Serban C.
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p. 667 - 677
(2022/02/02)
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- An Annelated Mesoionic Carbene (MIC) Based Ru(II) Catalyst for Chemo- And Stereoselective Semihydrogenation of Internal and Terminal Alkynes
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The catalytic utility of [RuL1(CO)2I2] (1), containing an annelated π-conjugated imidazo-naphthyridine-based mesoionic carbene (MIC) ligand (L1), is evaluated for E-selective alkyne semihydrogenation. The precatalyst 1, in combination with 2 equiv of AgBArF, semihydrogenates a broad range of internal alkynes with molecular hydrogen (5 bar) in water. (E)-Alkenes are accessed in high yields, and a number of reducible functional groups are tolerated. A chelate MIC ligand and two cis carbonyls provide a well-defined platform at the Ru center for hydrogenation and isomerization. The loss of two iodides and the presence of two carbonyls render the Ru center electron deficient and thus the formation of metal vinylidenes with terminal alkynes is avoided. This is leveraged for the semihydrogenation of terminal alkynes by the same catalytic system in isopropyl alcohol. Reaction profile, isomerization, kinetic, and DFT studies reveal initial alkyne hydrogenation to a (Z)-alkene, which further isomerizes to an (E)-alkene via metal-catalyzed Z → E isomerization.
- Bera, Jitendra K.,Choudhury, Joyanta,Das, Shubhajit,Dutta, Indranil,Pati, Swapan K.,Saha, Sayantani,Yadav, Suman
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p. 3212 - 3223
(2020/10/02)
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- A 2 - chloro - 5 - ethyl pyridine preparation method (by machine translation)
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The invention discloses a method for synthesizing 2 - chloro - 5 - ethyl pyridine method, by Suzuki reaction with 2 - chloro - 5 - bromo pyridine or by Wittig reaction with 2 - chloro - 5 - formyl pyridine is converted into 2 - chloro - 5 - vinyl pyridine; further uses the type (I) selective hydrogenation catalyst-containing structure, wherein R is cyclohexyl, butyl or phenyl, L is pyridine or unsaturated including nitrogen Cabeen, the 2 - chloro - 5 - vinyl pyridine is converted into 2 - chloro - 5 - ethyl pyridine. The method of the invention has a high selectivity, high yield and the advantage of convenient purification. (by machine translation)
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Paragraph 0019; 0037; 0038
(2017/08/25)
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- Methyl Hydrazinocarboxylate as a Practical Alternative to Hydrazine in the Wolff-Kishner Reaction
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Herein we describe a facile protocol for the reduction of aromatic ketones and aldehydes to the corresponding methylene unit. The procedure involves isolation of a carbomethoxyhydrazone intermediate that is easily decomposed to the reduced product without the requirement for large quantities of pernicious hydrazine.
- Cranwell, Philippa B.,Russell, Andrew T.,Smith, Christopher D.
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p. 131 - 135
(2015/12/26)
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- Direct Olefination of Alcohols with Sulfones by Using Heterogeneous Platinum Catalysts
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Carbon-supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant-free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt0 sites on the Pt metal particles are responsible for the rate-limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method. Olefination of alcohols: The first heterogeneous catalytic terminal and internal olefination of primary alcohols and methylenation of secondary alcohols with sulfones, a reusable carbon-supported Pt catalyst, and KOtBu is reported (see scheme).
- Hakim Siddiki,Touchy, Abeda Sultana,Kon, Kenichi,Shimizu, Ken-Ichi
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p. 6111 - 6119
(2016/04/26)
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- A Concise and Atom-Economical Suzuki-Miyaura Coupling Reaction Using Unactivated Trialkyl- and Triarylboranes with Aryl Halides
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A concise and atom-economical Suzuki-Miyaura coupling of trialkyl- and triarylboranes with aryl halides is described. This new protocol represents the first general, practical method that efficiently utilizes peralkyl and peraryl groups of the unactivated trialkyl- and triarylboranes for the Suzuki-Miyaura coupling reaction.
- Li, Hongmei,Zhong, Yong-Li,Chen, Cheng-Yi,Ferraro, Ashley E.,Wang, Dengjin
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supporting information
p. 3616 - 3619
(2015/07/28)
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- Process for the synthesis of 3-methyl-pyridine
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The present invention discloses a process for the synthesis of 3-methyl-pyridine from formaldehyde, paracetaldehyde, ammonia and acetic acid, whereby said compounds are reacted and said process comprises the following parameters: a) a reaction temperature of 260-300° C.;b) a molar ratio of formaldehyde and paracetaldehyde of 0.7-1-4 Mol/Mol:c) an ammonia concentration of 10-20 weight-%d) an acetic acid concentration of 4-20 weight-%e) a paracetaldehyde concentration of 0.4-1.6 Mol/kgf) a retention time of 10-30 minutes in case of a continuous reaction and 10-90 minutes in case of a discontinuous reaction; andg) a reaction pressure of 30-130 bar
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Page/Page column 1
(2011/01/12)
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- Deoxygenation of aldehydes and ketones using dichloro bis(1,4- diazabicyclo[2.2.2]octane)(tetrahydroborato) zirconium(IV)
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Saturated aldehydes and ketones are converted via their p-toluenesulfonyl hydrazones to the corresponding alkanes using dichloro bis(1,4-diazabicyclo[2.2. 2]octane)(tetrahydroborato) zirconium(IV) (ZrBDC). The reactions were performed in DMF-sulfolane at 110 °C and gave the corresponding alkanes in high yields. Regioselectivity in the reduction of α,β-unsaturated carbonyl groups was also observed.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Salehian, Fatemeh
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p. 170 - 172
(2007/10/03)
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- Inhibitors of cell proliferation, angiogenesis, fertility, and muscle contraction
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The invention concerns inhibitors of cell proliferation, angiogenesis, fertility, and muscle contraction, characterized by formula I wherein, X, Y and Z independently represent C or N; ------ is an optional double bond; n is 0 or 1; R1, R2, and R4 independently represent hydrogen, a chemical bond, C1-10 alkyl; C2-10 alkenyl; C2-10 alkinyl; aryl; aryl-C1-10 alkyl; C3-10 heterocyclyl; C5-10 heteroaryl; halo, CF3; NO2; NHC(O)R*, OR, said alkyl, alkenyl, alkinyl, aryl, arylalkyl, heterocyclyl, or heteroaryl being optionally substituted; R3, R5, and R6 independently represent hydrogen, C1-10alkyl; C2-10 alkenyl; C2-10 alkinyl; aryl; aryl-C1-10alkyl; C3-10 heterocyclyl; C5-10 heteroaryl; halo, CF3; NO2; NHC(O)R*, OR, said alkyl, alkenyl, alkinyl, aryl, heterocyclyl, or heteroaryl being optionally substituted; or R5 and R6 together form a 5- or 6-member aryl, heterocyclyl or heteroaryl group; R is hydrogen or C1-6 alkyl; R* is hydrogen, or C1-6 alkyl, or OH, wherein the optional substituents are preferably selected from the group of one to three OH, C1-6 alkyl, halo, NO2, C1-6 alkoxy, and CF3, or a pharmaceutically acceptable salt thereof.
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- Lewis acid-promoted oxidative addition of thioimidates to Pd(0)
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The isomeric S-methyldihydropyrrins 9-Z and 9-E exhibit markedly different behavior in Pd(0)-catalyzed cross-coupling reactions. Thioimidates 9-Z are readily converted to imines 10-Z employing Pd(0)/AlkZnI. Under identical conditions 9-E are inert. Oxidative addition to Pd(0) requires activation by Zn or other Lewis acids, which is sterically unfavorable with 9-E. Analogous results were obtained with the related thioimidates 11-E,Z as well as with methylthiopyridines 19α-γ. In the case of both 11 and 19 oxidative addition to Pd(0) was greatly facilitated in the presence of BF3·Et2O. The importance of Lewis acid activation to Pd(0) oxidative addition in such substrates appears to be a general phenomenon not previously recognized.
- Ghosh, Indranath,Jacobi, Peter A.
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p. 9304 - 9309
(2007/10/03)
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- New Synthesis of 3-Alkylpyridines
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An effective method is reported for preparation of 3-alkylpyridines from piperidine and C1-C10 aliphatic alcohols at 300-500 deg C in the presence of a dehydrogenating catalyst.
- Tereshko, A. B.,Tarasevich, V. A.,Kozlov, N. G.
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p. 258 - 259
(2007/10/03)
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- SYNTHESIS OF 3-N-BUTYLPYRIDINE - A TOXIC METABOLITE OF THE FUNGUS Fusarium oxysporum AND ITS HOMOLOGUES
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The interaction of the tri-n-butylphosphine complex of lithium di(3-pyridyl) copper(I) with 1-iodobutane and with other alkyl halides in ether at room temperature has given 3-n-butylpyridine and its homologues with yields of 82-89 percent.
- Goshaev, M. G.
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p. 391 - 393
(2007/10/02)
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- METHODS FOR INDOLE ALKALOID SYNTHESIS. A HIGHLY CONVERGENT STRATEGY FOR THE SYNTHESIS OF A 3-METHYL-6,7-DEHYDROASPIDOSPERMIDINE SYSTEM.
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The N1-CO2Me derivative of 2-ethyl-3-formylindole has been converted into the highly functionalized aspidospermidine-type alkaloid 12 in four steps.
- Magnus, Philip,Cairns, Peter M.,Kim, Chung Sook
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p. 1963 - 1966
(2007/10/02)
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- An Improved Liquid-Phase Synthesis of Simle Alkylpyridines
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The synthesis of pyridines from mixtures of aldehydes or ketones and NH3 in the liquid phase has been reinvestigated, using continuous dosage of the carbonyl components to the reaction mixture.The main product from the reaction of acetaldehyde and formaldehyde is 3-methylpyridine (6), which is also the main product from the reaction of acrolein or a mixture of crotonaldehyde and formaldehyde under the same conditions.The reaction of other aldehydes with formaldehyde give 3,5-dialkylpyridines, e.g. 10, 16.Acetone reacts with either formaldehyde or acetaldehyde to give polysubstituted alkylpyridines.A mechanistic pathway is proposed which accounts for the formation of the observed products.
- Grayson, J. Ian,Dinkel, Rolf
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p. 2100 - 2110
(2007/10/02)
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- Preparation of pyridines
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Pyridines are prepared by reacting a 2-alkoxy-2,3-dihydro-4H-pyran or a glutaraldehyde with ammonium nitrate in the presence of an aliphatic carboxylic acid and a catalytic amount of nitric acid. The pyridines which can be prepared by the process according to the invention are useful starting materials for the preparation of dyes, drugs and pest control agents and are useful solvents.
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- Catalytic Reactions of Pyridines. V. Alkylation of α-, β-, and γ-Picolines with Alcohols catalyzed by Ammonium Halides
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A new method was found for the homogeneous liquid-phase alkylation of α-, β-, and γ-picolines with either methanol or ethanol.Addition of a catalytic amount of an ammonium halide to a mixture of a picoline and an alcohol resulted in a great increase in the yields of both side-chain and α-alkylated derivatives of the starting picoline when the reaction was carried out at 320-335 deg C in an atmosphere of nitrogen.The higher the reaction temperature, the greater the yields of side-chain alkylated derivatives became.In practice, this alkylation gave 2-ethylpyridine, and 2,6-lutidine from α-picoline with methanol, 3-ethylpyridine and 2,5-lutidine from β-picoline from methanol, 4-ethylpyridine and 2,4-lutidine from γ-picoline with methanol, 2-propylpyridine and 2-ethyl-6-methylpyridine from α-picoline with ethanol, 2-ethyl-5-methylpyridine from β-picoline with ethanol, and 4-propylpyridine and 2-ethyl-4-methylpyridine from γ-picoline with ethanol.Keywords-alkylation; catalyst; ammonium halide; α-picoline; β-picoline; γ-picoline; ethylpyridine; propylpyridine; methanol; ethanol
- Kashiwagi, Hiroshi,Enomoto, Saburo
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p. 2213 - 2218
(2007/10/02)
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- Catalytic Reactions of Pyridines. IV. Heterogeneous Vapor-phase Side-chain Alkylation of Pyridines with Alcohols over Na+, K+, Rb+, and Cs+ Exchanged Zeolites
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The heterogeneous vapor-phase alkylation of pyridine with methanol over Na+, K+, Rb+, or Cs+ exchanged X- or Y-type zeolite in an atmophere of nitrogen resulted in the formation of 2- and 4-ethylpyridines and 2- and 4-vinylpyridines together with picolines and lutidines.Next, the alkylation of α-, β-, and γ-picolines with methanol was studied over alkali cation exchanged zeolites and was found to produce mainly the side-chain methylated derivatives: ethylpyridines and vinylpyridines.However, considerable amounts of ring-alkylated derivatives (lutidines) were formed simultaneously.In general, the catalytic activity became observable under reaction conditions involving both a high temperature and a small flow rate of carrier gas (N2).The yields of ethylpyridines were highest when the CsY catalyst was used at 450 deg C, whereas the yields of vinylpyridines were highest when the CsX catalyst was used at 425 deg C.This catalytic side-chain alkylation over alkali cation exchanged zeolites was successfully applied to a variety of picolines, lutidines, and ethylpyridines with either methanol or ethanol.
- Kashiwagi, Hiroshi,Enomoto, Saburo
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p. 404 - 411
(2007/10/02)
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- Transformations of pyridine bases on a nickel-aluminum catalyst
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The electronic structures of some pyridine bases are analyzed by means of 1H and 13C NMR spectroscopic data for substituted pyridines and the calculated bond orders in the pyridine ring. The differences in the chemical bonds in the pyridine ring of isomeric methylpyridines and the carbon-carbon bonds between the ring and the methyl groups in these compounds are in agreement with the experimental data on the thermal stability of the simplest pyridine bases and the gas-phase transformation of the isomeric methylpyridines on an industrial nickel-aluminum catalyst. The possibility of obtaining mono- or dialkylpyridines under these conditions, depending on the structure of the starting pyridine bases, is demonstrated.
- Antonova,Ovchinnikova,Bespalov,Serova,Promonenkov,Ustavshchikov
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p. 280 - 283
(2007/10/02)
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- Ligand interaction of sustituted pyridines with cytochrome P-450.
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A series of pyridyl ketones and alkyl pyridines was evaluated as type II ligands for cytochrome P-450. Activity as type II ligands was evaluated in terms of the lipid solubility and the pKa values of the compounds.
- Born,Early
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p. 850 - 851
(2007/10/02)
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- Production of pyridyl ketones
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Pyridyl ketones are produced from substituted pyridines containing at least one lower alkyl group or aryl-methylene group connected to a carbon of the pyridine nucleus by a methylene radical of such group, by air oxidizing the pyridine in the liquid phase at elevated temperature, e.g., 200° C., and pressure, e.g., 400 psig. The reaction is preferably carried out in the presence of an inorganic oxidation catalyst, such as a heavy metal or oxide or hydrated oxide or inorganic salt thereof, but with some pyridines, especially 2-substituted and 4-substituted pyridines, reaction occurs without a catalyst. The reaction mixture is fractionated to recover the pyridyl ketone and unreacted starting material.
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