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OH Proton (oh + proton)
Selected Abstracts9-Fluoro-18-hydroxy-[3.3]metacyclophane: Synthesis and Estimation of a C,F···H,O Hydrogen BondEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2004Hiroyuki Takemura Abstract A cyclophane composed of fluorobenzene and phenol units was synthesized in order to observe the C,F···H,O hydrogen bond. In the crystal structure, 20% of the molecule clearly shows the intramolecular hydrogen bond and the other 80% is free from hydrogen bonding. On the other hand, a distinct low-field shift of the phenolic OH proton was observed in the 1H NMR spectrum compared to that of the F-free analog. Furthermore, O,H···F through-space coupling was observed. From the results of the crystallographic analysis, IR, and NMR spectra, the C,F···H,O hydrogen bond energy of this system was estimated to be 0.84,3.7 kJ·mol,1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis and NMR spectral study of some t(3)-aryl- r(2),c(4)-bisethoxycarbonyl- t(5)-hydroxy- c(5)-methylcyclohexanonesMAGNETIC RESONANCE IN CHEMISTRY, Issue 5 2005K. Pandiarajan Abstract Six t(3)-aryl- r(2),c(4)-bisethoxycarbonyl- t(5)-hydroxy- c(5)-methylcyclohexanones (6,11) were synthesized by condensing ArCHO (Ar = Ph, p -O2NC6H4, p -CH3OC6H4, p -ClC6H4, m -O2NC6H4 and m -C6H5O6H4) with ethyl acetoacetate in the presence of methylamine and their 1H and 13C NMR spectra were recorded. 1H,1H COSY and NOESY spectra were recorded for 6 and 7 and also HSQC and HMBC spectra for 6 and 8. Elemental analysis was carried out for all compounds. The mass spectrum was recorded for 8. All analytical data are consistent with the proposed molecular formulae. Analysis of NMR spectral data suggests that these compounds largely adopt chair conformations with the hydroxyl group occupying an axial orientation and all the other substituents occupying equatorial orientations. Long-range coupling (2,3 Hz) between the OH proton and the axial methylene proton at C-6 is observed in 6, 7, 8 and 11. Copyright © 2005 John Wiley & Sons, Ltd. [source] 3-Hydroxybenzene 1,2,4-Trisphosphate, a Novel Second Messenger Mimic and unusual Substrate for Type-I myo -Inositol 1,4,5-Trisphosphate 5-Phosphatase: Synthesis and PhysicochemistryCHEMBIOCHEM, Issue 11 2006Stephen J. Mills Dr. Abstract 3-Hydroxybenzene 1,2,4-trisphosphate 4 is a new myo -inositol 1,4,5-trisphosphate analogue based on the core structure of benzene 1,2,4-trisphosphate 2 with an additional hydroxyl group at position-3, and is the first noninositol based compound to be a substrate for inositol 1,4,5-trisphosphate 5-phosphatase. In physicochemical studies on 2, when three equivalents of protons were added, the 31P NMR spectrum displayed monophasic behaviour in which phosphate-1 and phosphate-2 behaved independently in most of the studied pH range. For compound 4, phosphate-2 and phosphate-4 interacted with the 3-OH group, which does not titrate at physiological pH, displaying complex biphasic behaviour which demonstrated co-operativity between these groups. Phosphate-1 and phosphate-2 strongly interacted with each other and phosphate-4 experienced repulsion because of the interaction of the 3-OH group. Benzene 1,2,4-trisphosphate 2 is resistant to inositol 1,4,5-trisphosphate type I 5-phosphatase catalysed dephosphorylation. However, surprisingly, 3-hydroxybenzene 1,2,4-trisphosphate 4 was dephosphorylated by this 5-phosphatase to give the symmetrical 2,3-dihydroxybenzene 1,4-bisphosphate 16. The extra hydroxyl group is shown to form a hydrogen bond with the vicinal phosphate groups at ,15,°C, and 1H NMR titration of the ring and hydroxyl protons in 4 shows the OH proton to be strongly stabilized as soon as the phosphate groups are deprotonated. The effect of the phenolic 3-OH group in compound 4 confirms a critical role for the 6-OH group of the natural messenger in the dephosphorylation mechanism that persists even in radically modified analogues. [source] Determination of reactivity ratios and kinetics of free radical copolymerization of linalool with styrenePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2004Anjali Shukla Abstract Copolymerization of acyclic monoterpenoid, namely linalool (LIN), with styrene (STY) initiated by benzoyl peroxide (BPO) p -acetyl benzylidene triphenyl arsonium ylide (p -ABTAY) in xylene separately at 80°C for 180,min under inert atmosphere of nitrogen was performed. The results give a nearly alternating copolymer as evidenced from reactivity ratios (r1,=,0.016, r2,=,0.057) w.r.t. BPO; (r1,=,0.017, r2,=,0.052) w.r.t. p-ABTAY (i.e. r1,=,0.0165,±,0.0005 and r2,=,0.0545,±,0.0025 per initiator set) using Kelen,Tudos method. The FT-IR spectrum shows a band at 3026,cm,1 due to the aromatic ring of polystyrene and an alcoholic band of linalool at 3408,cm,1. 1H-NMR spectrum shows peaks at , 7.0,7.7,ppm of OH protons and peaks at , 7.5,8.0,ppm due to phenyl protons of styrene. The system follows ideal kinetics i.e. Rp,,,[LIN]1.0[STY]1.0[BPO]0.5/[p-ABTAY]0.5. The overall energy of activation in the temperature range 75,85°C is 77.0,kJ,mol,1 and 90.0,kJ,mol,1, respectively. The values for Mark,Houwink constants for the functional copolymer has been evaluated as a,=,0.40 and K,=,1.60,×,10,4 with the help of gel permeation chromatography (GPC). Alfrey,Price, Q and e parameters for linalool have been evaluated as Q2,=,0.80; e2,=,1.25,w.r.t. BPO and Q2,=,0.90; e2,=,1.54,w.r.t. p-ABTAY. Thermal properties of copolymers were investigated by thermogravimetric analysis (TGA) techniques. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||