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Acid Monohydrate (acid + monohydrate)
Selected AbstractsChemInform Abstract: Exploration of Chiral Induction on Epoxides in Lipase-Catalyzed Epoxidation of Alkenes Using (2R,3S,4R,5S)-(-)-2,3:4,6-Di-O-isopropylidiene-2-keto-L-gulonic Acid Monohydrate.CHEMINFORM, Issue 46 2009Kuladip Sarma Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Syntheses, spectral property, and antimicrobial activities of 6-,-amino dibenzo [d,f][1,3,2]dioxaphosphepin 6-oxidesHETEROATOM CHEMISTRY, Issue 1 2007M. Kasthuraiah Diethyl ,-aminophosphonates (4) were prepared in excellent yield from three-component reaction of aldehydes (1), amines (2), and triethylphosphite (3) under solvent-free conditions in the presence of ceric ammonium nitrate (CAN) and were reacted with 2,2,-dihydroxybiphenyl (5) using p -toluene sulfonic acid monohydrate (PTSA) as a catalyst to obtain 6-,-aminodibenzo[d f][1,3,2]dioxaphosphepin 6-oxides (6) in good yield. It is a first report on the cyclizations of 4 with 5. An antimicrobial activity of numbers of 6 is evaluated. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:2,8, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20244 [source] Desorption kinetics of model polar stratospheric cloud films measured using Fourier Transform Infrared Spectroscopy and Temperature-Programmed DesorptionINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2001Birgit G. Koehler This study combines Fourier transform infrared (FTIR) spectroscopy and temperature-programmed desorption to examine the evaporation kinetics of thin films of crystalline nitric acid hydrates, solid amorphous H2O/HNO3 mixtures, H2O,ice, ice coated with HCl, and solid HNO3. IR spectroscopy measured the thickness of each film as it evaporated, either at constant temperature or during a linear temperature ramp (temperature-programmed infrared, TPIR). Simultaneously, a mass spectrometer measured the rate of evaporation directly by monitoring the evolution of the molecules into the gas phase (temperature-programmed desorption, TPD). Both TPIR and TPD data provide a measurement of the desorption rate and yield the activation energy and preexponential factor for desorption. TPD measurements have the advantage of producing many data points but are subject to interference from experimental difficulties such as uneven heating from the edge of a sample and sample-support as well as pumping-speed limitations. TPIR experiments give clean but fewer data points. Evaporation occurred between 170 and 215 K for the various films. Ice evaporates with an activation energy of 12.9 ± 1 kcal/mol and a preexponential factor of 1 × 1032±1.5 molec/cm2 s, in good agreement with the literature. The beta form of nitric acid trihydrate, ,,NAT, has an Edes of 15.6 ± 2 kcal/mol with log A = 34.3 ± 2.3; the alpha form of nitric acid trihydrate, ,,NAT, is around 17.7 ± 3 kcal/mol with log A = 37.2 ± 4. For nitric acid dihydrate, NAD, Edes is 17.3 ± 2 kcal/mol with log A = 35.9 ± 2.6; for nitric acid monohydrate, NAM, Edes is 13 ± 3 kcal/mol with log A = 31.4 ± 3. The ,,NAT converts to ,,NAT during evaporation, and the amorphous solid H2O/HNO3 mixtures crystallize during evaporation. The barrier to evaporation for pure nitric acid is 14.6 ± 3 kcal/mol with log A = 34.4 ± 3. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 295,309, 2001 [source] Comparison of poly(o -anisidine) and poly(o -anisidine- co -aniline) copolymer synthesized by chemical oxidative methodJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010J. Longun Abstract In this study, poly(o -anisidine) [POA], poly(o -anisidine- co -aniline) [POA- co -A], and polyaniline [PANi] were chemically synthesized using a single polymerization process with aniline and o -anisidine as the respective monomers. During the polymerization process, p -toluene sulfonic acid monohydrate was used as a dopant while ammonium persulfate was used as an oxidant. N -methyl-pyrolidone (NMP) was used as a solvent. We observed that the ATR spectra of POA- co -A showed features similar to those of PANi and POA as well as additional ones. POA- co -A also achieved broader and more extended UV,vis absorption than POA but less than PANi. The chemical and electronic structure of the product of polymerization was studied using Attenuated Total Reflectance spectroscopy (ATR) and UV,visible spectroscopy (UV,vis). The transition temperature of the homopolymers and copolymers was studied using differential scanning calorimetry and the viscosity average molecular weight was studied by using dilute solution viscometry. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Comparison of the effects of pressure on three layered hydrates: a partially successful attempt to predict a high-pressure phase transitionACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2009Russell D. L. Johnstone We report the effect of pressure on the crystal structures of betaine monohydrate (BTM), l -cysteic acid monohydrate (CAM) and S -4-sulfo- l -phenylalanine monohydrate (SPM). All three structures are composed of layers of zwitterionic molecules separated by layers of water molecules. In BTM the water molecules make donor interactions with the same layer of betaine molecules, and the structure remains in a compressed form of its ambient-pressure phase up to 7.8,GPa. CAM contains bi-layers of l -cysteic acid molecules separated by water molecules which form donor interactions to the bi-layers above and below. This phase is stable up to 6.8,GPa. SPM also contains layers of zwitterionic molecules with the waters acting as hydrogen-bond donors to the layers above and below. SPM undergoes a single-crystal to single-crystal phase transition above 1,GPa in which half the water molecules reorient so as to form one donor interaction with another water molecule within the same layer. In addition, half of the S -4-sulfo- l -phenylalanine molecules change their conformation. The high-pressure phase is stable up to 6.9,GPa, although modest rearrangements in hydrogen bonding and molecular conformation occur at 6.4,GPa. The three hydrates had been selected on the basis of their topological similarity (CAM and SPM) or dissimilarity (BTM) with serine hydrate, which undergoes a phase transition at 5,GPa in which the water molecules change orientation. The phase transition in SPM shows some common features with that in serine hydrate. The principal directions of compression in all three structures were found to correlate with directions of hydrogen bonds and distributions of interstitial voids. [source] Hydrogen-bonding interactions in (3,4-dimethoxyphenyl)acetic acid monohydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2008Barbara Hachu The crystal structure of the title compound, C10H12O4·H2O, consists of (3,4-dimethoxyphenyl)acetic acid and water molecules linked by O,H...O hydrogen bonds to form cyclic structures with graph-set motifs R12(5) and R44(12). These hydrogen-bond patterns result in a three-dimensional network with graph-set motifs R44(20) and R44(22), and the formation of larger macrocycles, respectively. The C,C bond lengths and the endocyclic angles of the benzene ring show a noticeable asymmetry, which is connected with the charge-transfer interaction of the carboxyl or methoxy groups and the benzene ring. The title compound is one of the simple carboxylic acid systems that form hydrates. Thus, the significance of this study lies in the analysis of the interactions in this structure and the aggregations occurring via hydrogen bonds in two crystalline forms of (3,4-dimethoxyphenyl)acetic acid, namely the present hydrate and the anhydrous form [Chopra, Choudhury & Guru Row (2003). Acta Cryst. E59, o433,o434]. The correlation between the IR spectrum of this compound and its structural data are also discussed. [source] Application of mixtures of tartaric acid derivatives in resolution via supercritical fluid extractionCHIRALITY, Issue 6 2007Ildikó Kmecz Abstract Racemic N -methylamphetamine (rac -MA) was resolved with 2R,3R -tartaric acid (TA) and its derivatives (O,O,-dibenzoyl-(2R,3R)-tartaric acid monohydrate (DBTA) and O,O,-di- p -toluoyl-(2R,3R)-tartaric acid (DPTTA)), individually and using them in different combinations. After partial diastereomeric salt formation, the free enantiomers were extracted by supercritical fluid extraction using carbon dioxide as solvent. DBTA and DPTTA are efficient resolving agents for rac -MA, the best chiral separation being obtained at a molar ratio of 0.25 resolving agent to racemic compound for both resolving agents (eeE = 82.5% and eeE = 57.9%, respectively). Compared with the two other acids, TA is practically unsuitable for enantiomer separation (eeE < 5%). Applying a mixture of one individually active and one ineffective acid in half the equivalent molar ratio, when the acids are in 1:1 ratio in the mixture, the resolution efficiency values obtained exceeded those obtained by using the components individually. Decreasing the molar ratio of resolving agent mixture to 0.25, at which the individual resolving agents give the best chiral separation, the obtained resolution efficiency values did not differ significantly from those expected. The outcome of the resolution process depended only on the amount of the individually active resolving agents in the mixture. Chirality, 2007. © 2007 Wiley-Liss, Inc. 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