914-45-4Relevant academic research and scientific papers
Dissociation Constants of some Phenols and Homoconjugation Constants of the Corresponding Phenol-Phenolate Systems in Propylene Carbonate
Pawlak, Zenon,Magonski, Jozef
, p. 2807 - 2814 (1982)
The dissociation constants of eight phenols and homoconjugation constants of the corresponding phenol-phenolate systems in propylene carbonate were determined from e.m.f. measurements.The results are compared with those obtained previously in acetonitrile and acetone.The effect of the nitro-group on the decrease of the homoconjugation constant is found to be much greater than that of the chloro-substituent.In general, the stability of the homocomplexes insreases with the pKa value of the phenol.
Equilibrium acidities of superacids
Kuett, Agnes,Rodima, Toomas,Saame, Jaan,Raamat, Elin,Maeemets, Vahur,Kaljurand, Ivari,Koppel, Ilmar A.,Garlyauskayte, Romute Yu.,Yagupolskii, Yurii L.,Yagupolskii, Lev M.,Bernhardt, Eduard,Willner, Helge,Leito, Ivo
supporting information; experimental part, p. 391 - 395 (2011/04/17)
In this paper, we report the most comprehensive equilibrium superacidity scale that is available to date. Contrary to most of the past works, this scale is set up in a medium of constant composition and the obtained acidity values characterize the acidities of molecules rather than acidities of media. The current scale is thus complementary to the well-known H0 scale in the information that it provides. The solvent used is 1,2-dichloroethane (DCE). DCE has very weak basic properties (but sufficiently high polarity) and is an appropriate solvent for measuring acidities of very strong acids of diverse chemical nature. DCE acidities of well-known superacids (CF3SO 2OH, (CF3SO2)2NH, cyanocarbon acids, etc.) as well as common mineral acids (H2SO4, HI, HBr, etc.) are reported. Acidities of altogether 62 acids have been determined from 176 interlinked relative acidity measurements. The scale spans 15 orders of magnitude (from picric acid to 1,1,2,3,3-pentacyanopropene) and is expected to be a useful tool in design, use, and further acidity measurements of superacidic molecules.
Hydrogen-bond interactions of nicotine and acetylcholine salts: A combined crystallographic, spectroscopic, thermodynamic and theoretical study
Arnaud, Virginie,Berthelot, Michel,Evain, Michel,Graton, Jerome,Questel, Jean-Yves Le
, p. 1499 - 1510 (2008/02/04)
The hydrogen-bond (HB) interactions of the monocharged active forms of nicotine and acetylcholine (ACh) have been compared theoretically by using density functional theory (DFT) calculations and experimentally on the basis of crystallographic observations and the measurement of equilibrium constants in solution. The 2,4,6-trinitrophenolate (picrate) counterion was used to determine the experimental HB basicity of the cations despite its potential multisite HB acceptor properties. The preferred HB interaction site of the ammonium picrate salts was determined from a survey of crystallographic data found in the Cambridge Structural Database (CSD) and is supported by theoretical calculations. Two distinct classes of ammonium groups were characterised depending on the absence (quaternary ammonium) or presence (tertiary, secondary and primary ammoniums) of an N+ H...O hydrogen bond linking the two ions. The crystal structure of nicotinium picrate was determined and compared with that of ACh. This analysis revealed the peculiar behaviour of the ammonium moiety of nicotinic acetylcholine receptor (nAChR) ligands towards the picrate anion. Dedicated methods have been developed to separate the individual contributions of the anion and cation accepting sites to the overall HB basicity of the ion pairs measured in solution. The HB basicities of the picrate anions associated with the two different ammonium classes were determined in dichloromethane solution by using several model ion pairs with non-basic ammonium cations. The experimental and theoretical studies performed on the nicotine and ACh cations consistently show the significant HB ability of the acceptor site of nAChR agonists in their charged form. Both the greater HB basicity of the pyridinic nitrogen over the carbonyl oxygen and the greater HB acidity of the N+H unit relative to N+CH could contribute to the higher affinity for nAChRs of nicotine-like ligands relative to ACh-like ligands.
Infrared Spectroscopic Studies of Hydrogen Bonding in Triethylammonium Slats. Part 4. Rearrangement of Hydrogen-bonded Ion Pairs of Triethylammonium Salts caused by Interaction with Tetrabutylammonium Salts in Solution
Mashkovsky, Alexander A.,Nabiullin, Ahat A.,Odinokov, Stanislav E.
, p. 1879 - 1884 (2007/10/02)
Rearrangement of triethyl- and tetrabutylammonium salts in chloroform solution has been revealed from the characteristic features of the ν(N+H) bands caused by Fermi resonance interaction.Temperature changes of the i.r. spectra show this process to be reversible.Rearrangement constant K1 and K-1 and enthalpies -ΔH (for some cases only) of this process have been determined by measuring the total integrated intensities of the ν(N+H) bands of complexes which are in equilibrium.K1 values of the tetrabutylammonium salts increase with decreasing hydrogen bonding strength in triethylammonium salts.The measured enthalpies of rearrangement and those calculated from the ν(N+H) bands of hydrogen-bonded complexes studied are in agreement.It has also been shown that tetrabutylammonium salts anions can participate in the rearrangement of hydrogen-bonded ion pairs like the organic bases studied previously.
A STUDY OF REACTION OF AROMATIC POLYNITRO COMPOUNDS WITH TRIBUTYLSTANNYL HYDRIDE
Machacek, Vladimir,Lycka, Antonin,Nadvornik, Milan
, p. 2598 - 2606 (2007/10/02)
1H, 13C, 15N, and 119Sn NMR spectra have been used to study composition and structure of reaction products from 1,3,5-trinitrobenzene, methyl 2,4,6-trinitrobenzoate, 1-dimethylamino-2,4,6-trinitrobenzene, 1-methoxy-2,4,6-trinitrobenzene, 1-chloro-2,4,6-trinitrobenzene, 2,4,6-trinitrotoluene, 3,5-dinitrobenzonitrile and methyl 3,5-dinitrobenzoate with tributylstannyl hydride in the presence of tetramethylammonium bromide.
FORMATION OF PICRATES IN THE REACTIONS OF PICRYL HALIDES PicX (X = F, Cl, I) WITH ORGANOMETALLIC SALTS R3EM (E = Se, Ge AND M = Li, K, Cs), BORATES, AND CARBANIONS. POSSIBLE REACTION MECHANISMS
Artamkina, G. A.,Egorov, M. P.,Beletskaya, I. P.,Reutov, O. A.
, p. 1649 - 1659 (2007/10/02)
The reaction of picryl halides PicX (X = F, Cl, I) with organometallic compounds Me3SnM (M= Li, K, Cs), Et3GeK, borates Me4NBR4 (R = Bu, CH2SiMe3, CH2GeMe3), and 9-fluorenylpotassium was investigated.It was shown that for picryl fluoride and picryl chloride the reaction leads to the corresponding picrate.In the case of picryl iodide 1,3,5-trinitrobenzene is formed in addition to the picrate.The formation of the picrate also accompanies the reaction of PicX (X = F, Cl, I) with potassioacetoacetic ester, the main product from which is picrylacetoacetic ester.Possiblemechanisms are considered for the reaction leading to the picrates.
