501-52-0Relevant articles and documents
Rapid production of nitrilase containing silica nanoparticles offers an effective and reusable biocatalyst for synthetic nitrile hydrolysis
Swartz, Joshua D.,Miller, Scott A.,Wright, David
, p. 584 - 589 (2009)
Rapid and efficient immobilization of nitrilase within silica nanoparticles overcomes many hurdles associated with biocatalysis. A water-miscible dendrimer catalyzes the condensation of silicic acid to silica dioxide, entrapping electrostatically bound nitrilase molecules. Michaelis-Menten kinetics shows encapsulated nitrilase functions similarly to free nitrilase in solution. Additionally, HPLC analysis demonstrates that simple benchtop separation and recycling of the biocatalyst over 10 individual reactions are achieved without significant loss of enzyme and/or function. These findings broaden the use of nitrilases in the production of fine chemicals as well as general syntheses by overcoming some of the traditional barriers associated with enzyme reagents and nitrile conversion.
DITERPENOIDS AND FLAVONOIDS FROM CISTUS PALINHAE
Teresa, J. De Pascual,Urones, J. G.,Marcos, I. S.,Nunez, L.,Basabe, P.
, p. 2805 - 2808 (1983)
Cativic, ladenic, labdanolic, 8α-hydroxy-13(E)-labden-15-oic and 3-phenylpropionic acids were isolated from Cistus palinhae.In addition two new acids were characterized as 8α-methoxy-labd-15-oic and (5R,8R,9R,10S)-2-oxo-3-cis-cleroden-15-oic.From the neutral fraction were isolated the known 8,15-labdanediol, 8(17)labden-15-ol, 6-oxo-7-labden-15-ol and 6β-hydroxy-8(17)-labden -15-ol and also identified were the hydroxy derivatives 8α-hydroxy- 15-phenylpropionoxy-labdane-8α-hydroxy-15-acetoxy-labdane, 8-labden-15-ol and 8-epi-15-labdanediol.The weak acid fraction gave jaranol (5,4'-dihydroxy-3,7-dimethoxyflavone), genkwanin (5,4'-dihyyroxy-7-methoxyflavone), 3-methylkampferol and (-)betuligenol.Key Word Index-Cistus palinhae; Cistaceae; diterpenes; flavonoids.
Palladium-Catalyzed Selective β-Arylation of Aliphatic Amides Using a Removable N,O-Bidentate Auxiliary
Zhang, Shou-Kun,Yang, Xin-Yan,Zhao, Xue-Mei,Li, Peng-Xiang,Niu, Jun-Long,Song, Mao-Ping
, p. 4331 - 4339 (2015)
A new method for palladium-catalyzed β-arylation of aliphatic and cycloaliphatic amides without conventional silver salts utilizing 2-aminopyridine-1-oxide moiety (PyO) as an N,O-bidentate group has been developed. Reactions proceeded smoothly in DMSO solvent in the presence of K2HPO4·3H2O, providing the β-arylated aliphatic amide products in a moderate-to-good yield. An important cyclopalladium intermediate, successfully obtained with a modest yield, could be converted to the monoarylation product and be used as catalyst in arylation reaction. Moreover, the PyO directing group was easily removed under base condition to generate aliphatic acids.
Hydrogenation of Nitro and Unsaturated Organic Compounds over Catalysts Containing Nanosized Palladium Particles
Magdalinova,Klyuev
, p. 1024 - 1030 (2017)
The activity of palladium catalysts prepared on the basis of ZnO modified with polyethylene glycol (1 wt % Pd–PEG/ZnO) with molecular weights of 4000 and 6000 in the hydrogenation reaction of a series of nitro and unsaturated organic compounds has been studied. The catalysts are characterized by the formation of small metal particles with a size from 3 to 8 nm which uniformly coat the support surface. The results obtained have been compared to the catalytic properties of palladium-containing nanodiamonds and activated carbon under similar conditions.
Mild deprotection of methyl, benzyl, methoxymethyl, methylthiomethyl, methoxyethoxymethyl, and β-(trimethylsilyl)ethoxymethyl esters with AlCl3- N,N-dimethylaniline
Akiyama,Hirofuji,Hirose,Ozaki
, p. 2179 - 2185 (1994)
Methyl, benzyl, methoxymethyl, methylthiomethyl, methoxyethoxymethyl, and β-(trimethylsilyl)ethoxymethyl esters could be cleaved readily under mild conditions on treatment with AlCl3-N,N-dimethylaniline in CH2Cl2 to give parent carboxylic acids in high yields.
Effect of support and solvent on the activity and stability of NiCoB amorphous alloy in cinnamic acid hydrogenation
Bai, Guoyi,Dong, Huixian,Zhao, Zhen,Chu, Hailong,Wen, Xin,Liu, Chen,Li, Fei
, p. 19800 - 19805 (2014)
Selective hydrogenation of cinnamic acid was studied over different supported NiCoB amorphous alloys; a γ-Al2O3 supported NiCoB catalyst showed particularly good activity. The application of ultrasound during catalyst preparation was found to make the Ni active sites more dispersed, thus enhancing the catalyst activity. The NiCoB/γ-Al 2O3-u catalyst so obtained could be recycled effectively for nine runs in tert-butanol, in contrast it deactivated after only three runs in water. XPS, SEM and XRD characterizations indicated that loss of Ni and hydration of the γ-Al2O3 support were the main reasons for catalyst deactivation in water. Thus, an efficient and stable catalytic system involving NiCoB/γ-Al2O3-u and tert-butanol was established for cinnamic acid hydrogenation in this study.
Preparation of magnetic mesoporous core-shell nanocomposites for cinnamic acid hydrogenation
Liu, Xiaofang,Shi, Lingjuan,Feng, Wenhui,Niu, Libo,Liu, Chen,Bai, Guoyi
, p. 44302 - 44306 (2014)
A novel magnetic mesoporous core-shell nanocomposite Fe3O4@nSiO2@mSiO2@Ni-Co-B was prepared by the combination of a modified St?ber sol-gel process, a surfactant-templating method and self-assembly. It has a multi-shell structure with ferroferric oxide as core, dense nonporous silica and mesoporous silica as middle layers in sequence and an Ni-Co-B amorphous alloy as outer layer, as confirmed by transmission electron microscopy and nitrogen adsorption-desorption. This nanocomposite showed high activity and good selectivity in the selective hydrogenation of cinnamic acid to hydrocinnamic acid. Notably, it can be easily separated by a magnet after reaction due to its high magnetism and recycled effectively five times.
Application of Laser Induced Breakdown Spectroscopy as a Novel Approach for Monitoring of the Activity of Nano Palladium Catalyst as Compared to Two Well-known Methods
Belyani, Sahar,Keshavarz, Mohammad Hossein,Darbani, Seyyed Mohammad Reza,Tehrani, Masoud Kavosh
, p. 65 - 69 (2020)
Catalyst deactivation is an unavoidable process that occurs in catalytic chemical reactions. Laser Induced Breakdown Spectroscopy (LIBS) is used here as a novel approach to investigate the activity of palladium supported with carbon catalyst (Pd/C) over the hydrogenation of cinnamic acid with tetralin. Their outputs for four catalyst samples are reported for different time intervals of 0, 5, 10, 15 min during the reaction. The results of LIBS analysis are compared to Inductively Coupled Plasma Mass Spectrometry (ICP-MS), which shows a good agreement. Experimental data specify that line intensities of palladium (Pd) are decreased significantly with an increment of the reaction time. Moreover, the Field Emission Scanning Electron Microscope with energy dispersive spectroscopy (FESEM-EDS) of catalysts samples show aggregation of palladium particles for some places in the catalyst surface. The changes of Pd content and sintering of Pd particles in the catalyst during the reaction play substantial roles in catalyst deactivation.
Amide and lactam hydrolysis of N-(2-hydroxyacetyl)-2-pyrrolidone: Effective catalysis
Borboa, Lisaedy Garcia,Nunez, Oswaldo
, p. 737 - 743 (2006)
When N-(2-hydroxyacetyl)-2-pyrrolidone (open form) is dissolved in water at pH > 8, irreversible cleavage of the exocyclic and endocyclic amide C - N bond occurs. The latter rupture corresponds to the lactam opening yielding N-(4-hydroxyacetyl)butanoic acid (NBA). NBA is produced from the ester hydrolysis of the esteramide macrocycle that is in equilibrium with the cyclol form of the open form. We have previously reported this latter equilibrium for N-(2-aminoacetyl)-2-lactams. 2-pyrrolidone (lactam) and glycolic acid are produced from direct hydrolysis of the open form by means of the amide exocyclic cleavage. The [NBA]/[lactam] ratio increases at higher pH since the NBA production is second order with respect to [OH-] while the corresponding lactam formation is only first order. The obtained kobs is hence the sum of the rate constants that yield lactam and NBA, respectively. This kobs is uncatalyzed and specific base catalyzed with unusually high rate constants of 2.1 × 10-6s-1 and 0.025 M-1 s -1, respectively. The stability of the corresponding tetrahedral intermediate formed and the intramolecular alkoxy nucleophilic attack on the lactam carbonyl group combined with an effective protonation of the lactam nitrogen that promotes the C - N cleavage, contribute to increase the reaction rates and lactam opening. Rate constants for the two parallel reactions are obtained from kobs and [NBA]/[lactam] versus pH plots. Copyright
Mammalian exocrine secretions XVI. Constituents of secretion of supplementary sacculi of dwarf hamster, Phodopus sungorus sungorus
Burger,Smit,Spies,Schmidt,Schmidt,Telitsina
, p. 1277 - 1288 (2001)
As a first step in a study of the role of the secretion of the supplementary sacculi (buccal secretion) of the dwarf hamster, Phodopus sungorus sungorus, almost complete chemical characterization of the secretion was achieved. The 35 compounds identified include carbon dioxide, hydrogen sulfide, a large number of carboxylic acids (representing the bulk of the organic volatile fraction of the secretion), phenol, 2-piperidone, indole, two long-chain hydroxyesters, cholestrol, desmosterol, and lanosterol. The position of the double bonds in γ-icosadienyl-γ-butyrolactone and γ-henicosadienyl-γ-butyrolactone could not be determined, and these two compounds remained only partially characterized. Large variations were found in the relative concentrations in which the short-chain carboxylic acids are present in the secretions of individual animals, and although this aspect was not investigated in sufficient detail in the present investigation, the difference in the carboxylic acid profiles of the secretions of individual animals could play a role in individual recognition in this animal.