共查询到10条相似文献,搜索用时 55 毫秒
1.
The kinetics and thermodynamics of the liquid phase isomerization of an α- and β-pinene mixture on a Pd/C catalyst were studied.
The effects of pinene concentration, catalyst particle size, stirring rate, reaction temperature (293–423 K) and hydrogen
pressure (0.5–11 bar) on the rate of α- and β-pinene isomerization were investigated. The reaction rate of the α-pinene isomerization
has the first order with respect to the α-pinene concentration and 0.5 order with respect to the hydrogen pressure. The thermodynamic
parameters of the isomerization (Gibbs energy, reaction enthalpy and reaction entropy) and the equilibrium ratio of pinenes
under the conditions studied were determined. The general scheme of the reaction mechanism of α- and β-pinene isomerization
over the Pd/C catalyst was proposed. 相似文献
2.
This paper describes a procedure for the synthesis of two new volatile complexes, Pd(L1)2 and Pd(L2)2, from sterically hindered methoxy-β-iminoketones, where HL1 = C(CH3)2(OCH3)-C(NH)-CH2-C(O)-C(CH3)3; HL2 = C(CH3)2(OCH3)-C(NH)-CH2-C(O)-CH(CH3)2. Element analysis and IR spectral data are given. The results of full X-ray crystal structure analysis of the complexes are reported. The compounds have molecular structures; the crystals of the complexes have different symmetry groups and unit cell dimensions. The Pd(L1)2 complex molecule has a nonplanar structure; the Pd(L2)2 complex has a cis-structure. The geometrical characteristics obtained for the coordination units are as follows: the Pd-O and Pd-N bond lengths and N-Pd-O chelate angles were estimated at 1.960 Å, 93.7° for Pd(L1)2, and 1.984 Å, 1.976 Å, 92.4° for Pd(L2)2. 相似文献
3.
Maria Benedetta Fadda Nicoletta Curreli Raffaello Pompei Antonio Rescigno Augusto Rinaldi Enrico Sanjust 《Applied biochemistry and biotechnology》1994,44(3):263-270
A highly active thermostable β-glucosidase was purified to homogeneity from a strain ofTrichoderma sp. The enzyme was an extracellular glycoprotein and showed hydrolytic activity toward several β-glucosides.
Cellobiose was found to be the substrate of choice for this enzyme. This finding could suggest future technological applications
of the purified protein. 相似文献
4.
5.
Linli Xu Kai Xu Dehong Chen Qiukai Zheng Feiyue Liu Mingcai Chen 《Journal of Thermal Analysis and Calorimetry》2009,96(3):733-740
The effects of non-isothermal and isothermal crystallization on the formation of α- and β-phase in isotactic polypropylene
(iPP) with different content of β-nucleating agent are investigated by differential scanning calorimetry (DSC). On non-isothermal
crystallization, the content of β-phase and regularity of its crystals are depended on both cooling rate and the content of
β-nucleating agent. The faster cooling rate is, the lower of melting peak temperature (Tmp) and crystallization peak temperature (Tcp) of α- and β-phase are. The enthalpy of fusion (∆H) of β-phase increases with cooling rate in a certain range for the sample
with 0.1 wt% β-nucleating agent (G1) and decreases for that with 0.3 wt% β-nucleating agent (G3). On isothermal crystallization, the enthalpy of fusion of β-phase in G1 is higher than in G3 which is related to the efficiency of nucleation in different concentration of nucleating center in two samples. 相似文献
6.
Blends of known amounts of α- and β-PP crystals were prepared from pure α- and pure β-PPsamples. Their fusion behaviours were
studied by differential scanning calorimetry (DSC).The fusion heats of the α- and β-crystals were approximated from the DSC
curves and compared with those calculated on the basis of the compositions of the blends. A correction function was found
which improved the accuracy of the respective fusion heats significantly from the DSC analysis. The correction function can
be used to determine the respective fusion heats of a PP sample which contains an unknown mixture of the α- and β-crystals.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
B. B. Semenov K. A. Novikov Yu. I. Smushkevich V. N. Azev V. V. Kachala 《Chemistry of Heterocyclic Compounds》2005,41(10):1273-1279
A diastereodirected Pictet-Spengler reaction has been carried out to give the previously unknown 1-aryl(alkyl)-4-phenyl-β-carbolines
and it has been found that all of the β-carbolines diastereomers obtained have predominantly the R*,R*-configuration. The
diastereoselectivity of the given reaction is 44–70%.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1521–1528, October, 2005. 相似文献
8.
Vinod K. Tiwari Neetu Tewari Diksha Katiyar Rama P. Tripathi 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1297-1302
Summary. The one-pot reaction of β-glycosyl amino acids with β-ketoesters in the presence of Amberlite IR-120 resin and 4 ? molecular
sieve in refluxing toluene resulted in the respective dihydropyridones in fair to good yields.
Present address: Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221005, India. 相似文献
9.
N. V. Kovganko Yu. G. Chernov S. N. Sokolov Zh. N. Kashkan V. L. Survilo 《Chemistry of Natural Compounds》2009,45(2):200-204
New esters of 3β,5α,6β-trihydroxysteroids and 3β,5-dihydroxy-6-ketosteroids containing 6-chloropyridine groups characteristic
of the alkaloid epibatidine were synthesized by acylation with 6-chloronicotinoylchloride.
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 175-179, March-April, 2009. 相似文献
10.
Jianbiao Ma Zhidong Xie Yongjian Wang Yinong Wang Yunge Fan Binglin He 《中国科学B辑(英文版)》1997,40(4):405-411
A series of polymeric adsorbents with peptide pendants were designed as the artificial receptors of β-lactam antibiotics by
mimicking the structures of binding site in β-lactamases. Crosslinked poly(N, N-dimethyl acrylamide) gel as a carrier was
prepared by suspension copolymerization of N, N-dimethyl acrylamide and N. Ń-bisacryl-diaminoethane and then functionalized
with ethylenediamine after partial hydrolysis. Using solid-phase peptide synthesis with symmetrical anhydride of protected
amino acid step by step, various peptide pendants were respectively anchored onto the functionalized carrier. The adsorption
properties of these peptide-containing adsorbents for β-lactam antibiotics such as ampicillin and cefotaxime were then studied.
The results showed that only those adsorbents in which peptide chains contained more than one lysine residues could obviously
adsorb both β-lactams and that static interaction as well as hydrogen bond played an important role during the adsorption.
Project supported by the National Natural Science Foundation of China (No. 59493207). 相似文献