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1.
O. N. Lygo E. N. Khodot T. D. Nekipelova V. S. Kurova V. A. Kuz’min S. I. Firgang 《High Energy Chemistry》2010,44(3):189-195
A novel compound 1,2,2,3-tetramethyl-1,2-dihydroquinoline (1223TMDQ) was synthesized, and the products of its steady-state photolysis in water, MeOH, EtOH, trifluoroethanol (TFE), PrnOH, and BuiOH were analyzed by 1H NMR and mass-spectrometry. The corresponding adducts with water and alcohols were identified. The presence of the adducts
for alcohols with a number of carbon atoms n > 1 distinguishes 1223TMDQ from 2,2,4-trimethyl-1,2-dihydroquinolines with methyl-, alkoxy-, and hydroxy-substituents at
positions 1, 6, and 8, for which the formation of adducts was observed only in the presence of water and MeOH. The results
were interpreted in terms of the effect of steric hindrance caused by substituents in the heterocycle and increasing size
of the alkyl group of alcohol on proton transfer from a solvent to the molecule of 1,2-dihydroquinoline, which occurs in the
complex between the solvent and the dihydroquinoline molecule in the excited singlet state. It was shown that the main steric
hindrance for the photoinduced proton transfer in 2,2,4-substituted 1,2-dihydroquinolines is the substituent at position C(4)
of the heterocycle. 相似文献
2.
Mechanism of Photoinduced Addition of Water and Methanol to the Double Bond of 1,2-Dihydroquinolines
The kinetics and mechanism of photoinduced addition of water and methanol to the double bond of 2,2,4-trimethyl-1,2-dihydroquinoline (DHQ) bearing different substituents in the 6- and 8-positions and N-methylated DHQ were studied by flash photolysis. The reaction affords corresponding Markovnikov adducts, 4-hydroxy- and 4-methoxy-1,2,3,4-tetrahydroquinolines. On the basis of time-resolved experiments and the measurement of quantum yields of the reaction in media of different acidities or basicities, a general scheme of the reaction is suggested, which involves the formation of two intermediate species. The principal rate constants, activation parameters, and their dependence on substituents were determined. 相似文献
3.
Nekipelova T. D. Kurkovskaya L. N. Levina I. I. Shishkov V. S. Kuzmin V. A. 《Russian Chemical Bulletin》2001,50(4):673-677
Steady-state photolysis products of 6- and 8-substituted 2,2,4-trimethyl-1,2-dihydroquinolines in water and lower alcohols were identified by 1H NMR. In the case of electron-donor substituents, the solvent molecule is added to the double bond of the heterocycle affording the corresponding 4-hydroxy- or 4-alkoxytetrahydroquinolines. Nitro-substituted dihydroquinolines are photostable. The addition of EtOH and PrnOH occurs only in the presence of water to give a mixture of alkoxy- and hydroxy-adducts. A reaction scheme is suggested. 相似文献
4.
B. A. Lugovik L. G. Yudin P. V. Borodin S. M. Vinogradova A. N. Kost 《Chemistry of Heterocyclic Compounds》1971,7(6):741-743
The addition of benzene to 2,2,4-trimethyl-1,2-dihydroquinoline (I) in the presence of AlCl3 requires prior protonation or acylation of the amino group. Electron-donor substituents in the benzene ring of I hinder the reaction. The addition of halobenzenes proceeds under more severe conditions to give only para-substituted 4-aryl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinolines.See [1,2] for communications I and II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 795–797, June, 1971. 相似文献
5.
K. V. Komarov N. D. Chkanikov V. I. Suskina A. B. Shapiro A. F. Kolomiets A. V. Fokin 《Russian Chemical Bulletin》1989,38(2):415-417
1. | The alkylation of 2,2,4-trimethyl-1,2-dihydroquinoline and its derivatives by hexafluoroacetone occurs regioselectively and leads, depending on the conditions, to 6-(2-hydroxyhexafluoro-2-propyl)-2,2,4-trimethyl-1,2-dihydroquinolines or the 6,8-disubstituted products. |
2. | The reaction of methyl trifluoropyruvate with 2,2,4-trimethyl-1,2-dihydroquinoline gave the product of C8-alkylation, accompanied by lactamization. |
3. | The oxidation of 6-(2-hyhdroxyhexafluoro-2-propyl)-2,2,4-trimethyl-1,2-dihydroquinoline by hydrogen peroxide in the presence of sodium tungstenate gave a stable nitroxyl radical. |
6.
The rate constants and activation parameters of the reactions of the carbocation resulting from 6-ethoxy-1,2,2,4-tetramethyl-1,2-dihydroquinoline
photolysis with methanol (k
1) and the methoxide ion (k
2) have been measured by flash photolysis in binary mixtures of methanol with inert solvents (nonpolar pentane and polar acetonitrile)
in wide composition ranges. The changes in the activation parameters for k
1 at different solvent compositions show that the increase in the rate constant in the pentane mixtures is mainly deter-mined
by the increase in the preexponential factor. The decrease in k
1 in the acetonitrile mixtures is deter-mined by the decrease in the methanol concentration and by the increase in the activation
energy. The different roles of the methoxide ion in the reaction are demonstrated. They depend on the nature of the inert
solvent in the mixture. The results of this study are considered in terms of methanol clustering in pentane and acetonitrile,
the different solubilities of 6-ethoxy-1,2,2,4-tetramethyl-1,2-dihydroquinoline in the components of the binary mixtures,
and the difference in distribution and solvation between the carbocation and the methoxide ion in the mixtures. 相似文献
7.
The rate constants of the decay of carbocation generated in the photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline and the composition of reaction products were studied as a function of solvent composition in the mixtures H2O–ROH and MeOH–ROH (R = Et, n-Pr, and i-Pr). The rate constants of carbocation decay in alcohols are more than 20 times higher than the corresponding rate constants in water. As follows from the composition of the products obtained in the photolysis in the alcohol–water mixtures, MeOH is only 1.4 times more reactive than water, and EtOH and n-PrOH are even less active than water. The inconsistency in the product composition in the mixtures and the values of the observed rate constants in these solvents was explained by the two-step mechanism of the reaction: the reversible formation of an adduct of the carbocation with the solvent components and subsequent proton transfer to the solvent to form the final product, with the first step determining the product composition and the second step determining the rate of carbocation decay. The relative rate constants of alcohols and water were determined for the two steps. The preferred solvation of the carbocation with water also contributes significantly to the reaction kinetics and the product composition in the water–alcohol solutions. 相似文献
8.
T. D. Nekipelova 《High Energy Chemistry》2010,44(4):290-296
The photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline in binary MeOH-C5H12 and MeOH-MeCN mixtures was studied in dependence on the solvent composition by steady state and pulse photolysis. The photoinduced
proton transfer from the N-H bond to the C(3) carbon atom of the heterocycle does not occur up to the methanol concentration
of 0.25 (1 vol %) and 2.5 mol l−1 (10 vol %) in the MeOH-C5H12 and MeOH-MeCN mixtures, respectively. The trends in the increase in the relative quantum yield of the proton transfer reaction
(Q
mix/Q
MeOH) and the decay rate constant for 2,2,4,6-tetramethyl-2,3-dihydroquinoline, the product of the proton transfer reaction, in
dependence on the composition differ significantly for these binary mixtures. The results are interpreted in terms of peculiarities
in the aggregation of methanol and the distribution of the DHQ molecules and transient species in the mixtures. 相似文献
9.
The spectral and kinetic parameters of transient species generated in the irradiation of 6-ethoxy-2,2,4-trimethyl-8-nitro-1,2-dihydroquinoline
were examined by stationary and pulse photolysis in the solvents: heptane, acetonitrile, methanol, and ethanol. Upon excitation
of the long-wavelength absorption band (λex > 450 nm), a reversible photochemical reaction was revealed, and the spectral and kinetic parameters of three transient species
observed in the photolysis were characterized (λmax = 390, 400, and 420 nm (acetonitrile), k = 97, 500, and 2000 s−1, respectively). The absorption spectra and the rate constants of the decay of transient species are almost independent of
the medium polarity and the presence of oxygen in the system. The excited state generated during irradiation to the short-wavelength
absorption band (290 < λex < 350 nm) is inactive in the photochemical reaction and deactivates without the formation of transient species. The mechanism
of the reversible photochemical reaction is suggested, which involves the opening of the heterocycle N-C bond upon photoexcitation
of the long-wavelength absorption band and the thermal back reaction. 相似文献
10.
O. N. Lygo I. V. Shelaev F. E. Gostev T. D. Nekipelova E. N. Khodot V. A. Kuzmin O. M. Sarkisov 《High Energy Chemistry》2012,46(1):34-37
Dynamics of the formation of the carbocation in the ground state as a result of photoinduced proton transfer from a solvent
to the excited state of 1,2,2,3-tetramethyl-1,2-dihydroquinoline (3MDHQ) in MeOH and 2,2,2-trifluoroethanol (TFE) was registered
by pump-probe laser photolysis (λpump = 310 nm) with femtosecond time resolution. The lifetimes of the excited singlet state of 3MDHQ τ = 115 and 780 ps were determined
in TFE and MeOH, respectively. The transient species with absorption spectrum corre-sponding to the spectrum of the carbocation
from 3MDHQ (λmax = 480 nm) is generated at time delays lower than 500 fs from the unrelaxed excited singlet state. 相似文献
11.
T. D. Nekipelova L. N. Kurkovskaya I. I. Levina N. A. Klyuev V. A. Kuzmin 《Russian Chemical Bulletin》1999,48(11):2049-2054
Products of the steady-state photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline (1) in water, methanol, and water—ethanol were isolated for the first time and identified by1H and13C NMR spectroscopy, IR spectroscopy, and mass spectrometry. As a result of the photolysis, the molecule of the solvent is
added to the double bond of the heterocycle with formation of 4-hydroxy- (2) or 4-methoxy-2,2,4,6-tetramethyl-1,2,3,4-tetrahydroquinoline (3) in water and methanol, respectively. Compounds2 and3 are converted gradually into1 in the dark. The rate of the back reaction depends on the solvent and the concentration of the product. Comparison of the
products of the photolysis in methanol and hexane at 45 °C and of the azoisobutyronitrile-initiated oxidation of1 at the same temperature has shown that unlike the photolysis in hexane, aminyl radicals are not precursors of the product
of the photolysis in methanol. The reaction proceedsvia an excited singlet state.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2072–2077, November, 1999. 相似文献
12.
T. D. Nekipelova 《Russian Chemical Bulletin》1994,43(5):894-896
The locus of solubilization of 6-R-2,2,4-trimethyl-1,2-dihydroquinoline molecules (R=Me, OEt) in sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) has been determined by comparing the UV spectra of micellar solutions of the dihydroquinolines and their solutions in solvents of various polarities. The parameterR
pv (defined as the ratio of the absorbance of the long-wave band maximum to that at the adjacent valley) decreases with an increase in the solvent polarity in the order:n-heptane > 2-propanol > ethanol > H2O. In SDS micellar solutions,R
pv is close to the corresponding value in water and does not depend on [SDS]. In CTAB micellar solutions,R
pv is essentially greater than in water and increases with [CTAB]. Thus, the solubilized dihydroquinoline molecules in SDS micelles reside in the Stern layer, and in CTAB micelles they are located both in the interior of the micelle and in the Stern layer; in this case the micelle packing begins from the core.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 948–950, May, 1994. 相似文献
13.
L. Légrádi 《Mikrochimica acta》1970,58(6):1116-1120
Zusammenfassung Das Antioxydans 6-Äthoxy-2,2,4-trimethyl-1,2-dihydrochinolin (I) enthält als Beimengungen p-Phenetidin und 6-Äthoxy-2,4-dimethylchinolin (II). p-Phenetidin kann neben I und II mittels 2,4-Dinitrofluorbenzol nachgewiesen werden. I gibt mit Natriumnitrit in saurem Medium eine Farbreaktion; damit kann es nachgewiesen werden. Dabei setzen sich p-Phenetidin und II nicht um. Außerdem kann I neben p-Phenetidin und II mit Chloramin T nachgewiesen werden.
Marken: Topanol ICI, England; Santoquin Monsanto, USA; Niflex Nitrokémia, Ungarn. 相似文献
Detection of 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline and p-phenetidine in the presence of each other
Summary The antioxidant 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (I) contains as admixturesp-phenetidine and 6-ethoxy-2,4-dimethylquinoline (II).p-Phenetidine can be detected in the presence of (I) and (I) by means of 2,4-dinitrofluorobenzene. (I) yields a color reaction with sodium nitrite in acid medium; hence it may be detected.p-Pheneteidine and (II) give no response. Furthermore (I) may be detected in the oresence ofp-phenetidine and (II) by means of chloramine T.
Marken: Topanol ICI, England; Santoquin Monsanto, USA; Niflex Nitrokémia, Ungarn. 相似文献
14.
Tapparo A Artioli G Angelini I Favaro G 《Analytical and bioanalytical chemistry》2011,399(7):2389-2393
Prehistoric artifacts turning blue in the store rooms of the Natural History Museum in Verona, Italy recently raised serious
issues for heritage materials conservation. Our analytical investigation showed that the unusual discoloration process of
the flint tools is caused by the surface presence of at least three previously unknown pigmenting molecules of the triphenylmetane
dyes class: 6-(bis(2,2,4-trimethyl-1,2-dihydroquinolin-6-yl)methylene)-2,2,4-trimethyl-2,6-dihydroquinolinium and its hydrogenated
derivatives 2,2,4-trimethyl-6-((2,2,4-trimethyl-1,2,3,4-tetrahydroquinolin-6-yl)(2,2,4-trimethyl-1,2-dihydroquinolin-6-yl)methylene)-2,6-dihydroquinolinium
and 6-(bis(2,2,4-trimethyl-1,2,3,4-tetrahydroquinolin-6-yl)methylene)-2,2,4-trimethyl-2,6-dihydroquinolinium. The peculiar
formation of the molecules is possibly catalyzed within the silica pore surface starting from a well-known rubber stabilizer
2,2,4-trimethyl-1,2-dihydroquinoline released by the plastic pads flooring the storing cabinets. The investigated reaction
and its surprising blue product represent a case study of the application of modern materials science to conservation and
a serious warning towards the unpredictable challenges faced in the preservation of our cultural heritage. 相似文献
15.
O. N. Lygo I. V. Shelaev F. E. Gostev T. D. Nekipelova E. N. Khodot Yu. P. Tsentalovich A. A. Titov V. A. Kuzmin O. M. Sarkisov 《High Energy Chemistry》2013,47(5):230-236
Dynamics of transformations of excited states and active transient species generated in the photolysis of nitrated 1,2-dihydroquinolines (N-DHQ) has been studied by femto- and nanosecond laser pulse photolysis. Spectral and kinetic parameters of primary photophysical and photochemical processes have been determined, and their dependence on the substituent position at the aromatic ring of 1,2-dihydroquinoline (DHQ) and on the wavelength of excitation light has been established. The lifetime of the excited singlet state S1 in N-DHQ is ca. 100 and 500 fs for 8- and 6-nitro-substituted DHQ, respectively, which is shorter in comparison with DHQ without the nitro group by a factor of 104 and more. The major decay channel of the S1 state is the successive formation of three transient species with lifetimes of 0.5 to 16 ps. A triplet state is generated only upon excitation of the short-wavelength band by UV light. The quantum yield of the triplet state depends on the structure of N-DHQ. 相似文献
16.
Martin W. Stanford Julia I. Schweizer Maximilian Menche Gary S. Nichol Max C. Holthausen Michael J. Cowley 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1343-1347
The equilibrium between disilenes (R2Si=SiR2) and their silylsilylene (R3Si?SiR) isomers has previously been inferred but not directly observed, except in the case of the parent system H2Si=SiH2. Here, we report a new method to prepare base‐coordinated disilenes with hydride substituents. By varying the bulk of the coordinating base and other silicon substituents, we have been able to control the rearrangement of disilene adducts to their silylsilylene tautomers. Remarkably, 1,2 migration of a trimethylsilyl group is preferred over hydrogen migration. A DFT study of the reaction mechanism provides a rationale for the observed reactivity and detailed information on the bonding situation in base‐stabilized disilenes. 相似文献
17.
O. N. Lygo T. D. Nekipelova E. N. Khodot V. A. Kuzmin V. V. Shakhmatov V. A. Volnukhin V. V. Vargin A. B. Shevelev A. V. Shibaeva 《High Energy Chemistry》2012,46(3):171-176
Spectral, luminescent, and photochemical properties of 7,7,9-trimethyl-6,7-dihydrofuro[3,2-f]quinoline (FDHQ) have been studied in hexane, alcohols, and water. Unlike 1,2-dihydroquinolines without the furo substituent, the fluorescence
quantum yields for FDHQ in water and methanol are high (0.4 and 0.2, respectively), thereby indicating a difference in routes
of excitation energy degradation in these compounds. The regularities in the FDHQ phototransformations have been studied by
steady-state photolysis. The composition and the yield of final products depend on the presence or absence of oxygen in the
system to a higher extent than on the solvent nature. This indicates the participation of the triplet excited state in the
photo-chemical reactions in oxygen-free systems. 相似文献
18.
Natalie M. Williamson 《Tetrahedron》2005,61(1):155-165
The cyclisation of N-(1,1-dimethylpropargyl) anilines, using cuprous chloride in refluxing toluene, yields 6-substituted-2,2-dimethyl-1,2-dihydroquinolines. The reactivity of the double bond in the heterocyclic ring of these products is exemplified by chlorination, to yield 6-substituted-3,4-cis-dichloro-2,2-dimethyl-1,2,3,4-tetrahydroquinolines which can be selectively dechlorinated to provide 6-substituted-3-chloro-2,2-dimethyl-1,2,3,4-tetrahydroquinolines; epoxidation to yield an epoxide, which can be hydrogenolysed to the corresponding 3-hydroxy product and in turn oxidised to the 3-keto derivative; and oxymercuration to provide a 4-hydroxy product and hence a 4-keto derivative. Dehydrochlorination of a 3,4-dichloro product provides a 3-chloro-1,2-dihydroquinoline which can be hydrolysed to a 3-keto system. The formation of cis 3,4-dichloro products from the chlorination, as well as the formation of a cis chlorohydrin from the chlorination of N-acetyl-2,2,6-trimethyl-1,2-dihydroquinoline in partially aqueous solution, suggests that N-acetyl, or N-trifluoroacetyl groups, participate in the addition process. 相似文献
19.
Intramolecular CH Activation and Metallacycle Aromaticity in the Photochemistry of [FeFe]‐Hydrogenase Model Compounds in Low‐Temperature Frozen Matrices 下载免费PDF全文
Wyatt A. Thornley Prof. Thomas E. Bitterwolf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18218-18229
The [FeFe]‐hydrogenase model complexes [(μ‐pdt){Fe(CO)3}2], [(μ‐edt){Fe(CO)3}2], and [(μ‐mdt){Fe(CO)3}2], where pdt=1,3‐propanedithiolate, edt=1,2‐ethanedithiolate, and mdt=methanedithiolate, undergo wavelength dependent photodecarbonylation in hydrocarbon matrices at 85 K resulting in multiple decarbonylation isomers. As previously reported in time‐resolved solution photolysis experiments, the major photoproduct is attributed to a basal carbonyl‐loss species. Apical carbonyl‐loss isomers are also generated and may undergo secondary photolysis, resulting in β‐hydride activation of the alkyldithiolate bridge, as well as formation of bridging carbonyl isomers. For [(μ‐bdt){Fe(CO)3}2], (bdt=1,2‐benzenedithiolate), apical photodecarbonylation results in generation of a 10 π‐electron aromatic FeS2C6H4 metallacycle that coordinates the remaining iron through an η5 mode. 相似文献
20.
The triphenylarsine-catalyzed approach for the highly stereoselective synthesis of trans-2,3-dihydro-spiro[cyclopropane-1,2′-indan-1′,3′-dione] with alkenes and phenacyl bromide in organic solvent is described. The triphenylarsine-catalyzed cyclopropanation in water was investigated. The mixture of cis/trans isomers is provided with water as a solvent. The cis isomer is formed using water as a solvent. The reactivity of the reaction in water is higher than that in the organic solvent. 相似文献