733-60-8Relevant academic research and scientific papers
Binding of acetylcholine and tetramethylammonium to flexible cyclophane receptors: Improving on binding ability by optimizing host's geometry
Sarri, Paolo,Venturi, Francesca,Cuda, Francesco,Roelens, Stefano
, p. 3654 - 3661 (2007/10/03)
The structure of a cyclophanic tetraester (1), previously employed for investigations on the cation-π interaction, has been optimized to better accommodate acetylcholine (ACh) and tetramethylammonium (TMA) guests. Following indications from molecular modeling calculations, a flexible cyclophane receptor of significantly improved binding properties has been obtained by removing the four carbonyl groups of the parent host. 2,11,20,29-Tetraoxa[3.3.3.3]paracyclophane (2) was prepared by an improved procedure, which was conveniently devised to avoid the formation of contiguous cyclooligomers that caused serious separation issues. Association of 2 with TMA picrate was measured in CDCl3 at T = 296 K by 1H NMR titrations and compared to binding data obtained for a set of reference hosts, including the parent tetraester 1, the corresponding cyclophanic tetraamine, the open-chain counterpart of 2, and its cyclooligomers from pentamer to octamer. Binding enhancements ranging from 15-fold (with respect to the tetraester and the tetraamine) to over 80-fold (with respect to the open-chain tetraether) were achieved by geometry optimization of the host. Binding of 2 to ACh and TMA was investigated for a variety of counterions. A constant binding free energy increment of nearly 8 kJ mol-1 with respect to 1 was observed, independent from the anion and irrespective of the different structure of the cationic guests. Results showed that the electrostatic inhibiting contribution of the counterion to the cation's binding is a characteristic constant of each anion. The value of -ΔG° = 44.9 kJ mol-1 extrapolated for TMA in the absence of a counterion indicates that 28-34 kJ mol-1 of binding free energy are lost in ion pairing.
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.
REACTION OF METHYL AND PHENYL PICRATES WITH NUCLEOPHILES
Artamkina, G. A.,Egorov, M. P.,Beletskaya, I. P.,Reutov, O.A.
, p. 25 - 31 (2007/10/02)
The reactions of 2,4,6-trinitroanisole with various nucleophiles Me3SnM, Me3SiLi, BuLi, Me4NBBu4, PhMgI, CN-, lithium (potassium) succinimide, F-, Cl-, Br-, SCN-, NO2-, NO3-, HCO3-, PhSO2-,AcO-, S2- were investigated.It was found that the final products are the picrate and the corresponding methyl derivatives.The formation of intermediate ? complexes was detected in a series of the reactions (Me3SnLi, potassium succinimide, Bu4B-, CN-, NO2-, PhSO2-).Possible mechanisms for the reaction are examined.Reactions of 2,4,6-tricyanoanisole and phenyl picrate with certain nucleophiles were also investigated.
