The quantum-chemical modeling mechanism of the [4+2]-cycloaddition reaction of 2,3 dimethylbuta-1,3-diene and methyl acrylate was conducted. Its qualitative aspects were analyzed at the molecular level by the program MOPAC2012 and semiempirical method RM1. The potential energy surfaces of 2,3 dimethylbuta-1,3-diene and methyl acrylate [4+2] cycloaddition possible reaction pathways were constructed by restricted and unrestricted Hartree-Fock approximation. It has been established that the molecule of the final product methyl-3,4-dimethylcyclohex-3-encarboxylate has the half-chair shape, wherein the carboalkoxyl group is in the exo-orientation. Interaction between molecules of 2,3 dimethylbuta-1,3-diene and methyl acrylate occurs by a two-step mechanism more likely than one-step, since the activation parameters of this interaction maximum coincide with the experimental data.
In this paper, modified hydrothermal method for Ti-MWW catalyst preparation has been shown. Instrumental analysis of the zeolite material Ti-MWW has been performed by means of UV-vis spectrometry, infrared spectrometry (IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray microanalysis. Moreover, the results of the epoxidation of diallyl ether (DAE) over the titanium silicate catalyst Ti-MWW and in the presence of methanol have been presented. t-Butyl hydroperoxide have been applied for the first time as an oxidant for this process. The influence of temperature (20-130°C), DAE/TBHP molar ratio (1:1-3:1), methanol concentration (10-80 wt%), amount of catalyst (1-7 wt%) and reaction time (60-1440 min.) was studied. The main functions describing the process were determined on the basis of the results obtained from the gas chromatography method.
DFT calculations indicate that the decomposition reaction of nitroethyl benzoates in the presence of 1,3-dimethylimidazolium cation takes place much faster than in the case of the non-catalyzed process. Additionally, our calculations suggest one-step polar mechanism of title reactions.
Preliminary experiments shows, that [3+2] cycloadditions reactions proceeds with full regioselectivity and high stereoselectivity. In consequence, 3,4-trans-2-methyl-3-(3,4,5-trimethoxyphenyl)-4-halo-4-nitroisoxazolidines are forming as predominantly (or sole) products. Additionally, prognosis for the synthesized compounds to be potential ingredients of drugs is good.
The evaluation and selection of energy technologies involve a large number of attributes whose selection and weighting is decided in accordance with the social, environmental, technical and economic framework. In the present work an integrated multiple attribute decision making methodology is developed by combining graph theory and analytic hierarchy process methods to deal with the evaluation and selection of energy technologies. The energy technology selection attributes digraph enables a quick visual appraisal of the energy technology selection attributes and their interrelationships. The preference index provides a total objective score for comparison of energy technologies alternatives. Application of matrix permanent offers a better appreciation of the considered attributes and helps to analyze the different alternatives from combinatorial viewpoint. The AHP is used to assign relative weights to the attributes. Four examples of evaluation and selection of energy technologies are considered in order to demonstrate and validate the proposed method.
Two potential energy surfaces 1 2A1 and 1 2B1 for linear geometry of F-H-Br system have been computed with aug-cc-pVQZ basis set using dynamically weighted state averaged MCSCF followed by MRCI-F12 method. State 1 2A1 has smaller barrier height (3.49 kcal/mol) than 1 2B1. (13.6 kcal/mol). The latter has deep van der Waals well in Br-HF valley (2.12 kcal/mol).
The process of racemisation of atropisomeric biaryls was modelled by means of DFT calculations at an advanced B3LYP/6-31G* theoretical level. Thus, the detailed protocol of determination of the racemisation rate presented herein provides a practical prediction tool for elucidation of the configurational stability of atropisomers.
Experimental and computational approaches were used to estimate the lipophilicity of novel 1,2,4-triazole derivatives. These derivatives have been subjected to this research, because they exhibit antimicrobial activity. The chromatographic analysis of RP-HPLC and RP-TLC was carried out using methanol-water or acetonitrile-water as mobile phase. The linear relationships between logk (or R_M) values and the concentration of organic modifier were obtained. The lipophilicity was expressed as chromatographically derived descriptors: ?logk?_W, S, ?0 and scores logk and R_Mcorresponding to the first principal component. The experimental lipophilicity data have been compared with the computer calculated lipophilicity parameters (milogP, clogP, ALOGPs, AClogP, AlogP, MLOGP, KOWWIN, XLOGP2, XLOGP3, ?logP?_ChS) of the same molecules. The matrices were created with ?logk?_W or R_M^0and logP and they have been the subject of PCA analysis.
The current development of polyurethane self-healing materials has been evaluated and reviewed. Three main ways of self-healing – microcontainers, microvascular networks and reversible polymers - are described, and recent most prominent examples of self-healing materials applications presented.
The title compound - (Z)-1-bromo-1-nitro-2-phenylethene - was prepared by a three-step reaction. Its structure was con?rmed by spectral analysis as well as X-ray crystallography. It was found, that the compound crystallized in the orthorhombic system, space group Pbca, a=11.5296(6)Å, b=7.5013(5)Å, c=19.7187(12)Å, Å=B=Å=90°, Z=8.