In this paper we wish to report our results on investigation of the kind and the concentration of the hydroperoxides initiators on the polymerization rate. Four kinds of peroxides with different concentration have been examined such as), tert-butyl hydroperoxide (TBHP), cumene hydroperoxide (CHP), methyl ethyl ketone hydroperoxide (MEKP) and benzoyl peroxide (BP). Results show that the rate of the reaction depends on the type and percentage of initiators.

Cyclodextrins (CDs) are natural‐occurring oligomers with a hydrophobic cavity which allow them to form inclusion complexes in water with a variety of organic molecules. These complexes are generally stabilized by van der Waals and hydrophobic interactions, although specific host‐guest interactions can also play an important role.[1] In addition, geometrical and orientational requirements of both the guest and the host may control the association process, whereas the dissociation rate is determined by the strength of the interactions.[2] Therefore, a change of the cavity size or the rigidity of the host has dramatic effects on both the association and the dissociation rate constants and in consequence on the stability of the complexes.[3] Moreover, for a certain guest, stoichiometry and geometry of the inclusion complexes may also be much dependent on the host cavity size.[4] In this work we study the effects of CD cavity size on the stoichiometry, stability and structure of the complexes formed between the synthetic organic probe Dapoxyl and three natural cyclodextrins (α‐CD, β‐CD and γ‐CD) differing in the size of their inner cavity, using steady‐state and time‐resolved fluorescence techniques. The ditopic structure of this fluorophore together with its high sensitivity to the surroundings make it a useful model molecule to study the geometrical effects on the complexation. Complexation provokes strong changes in the fluorescent properties of Dapoxyl with a large blue shift of its emission spectrum and a great increase of the fluorescence quantum yield. The differences observed for the three CDs regarding stoichiometry, stability and fluorescence properties of the complexes are discussed on the basis of a size‐selective complexation of the Dapoxyl.

Quantitative structure-affinity relationships were applied to a series of 27 disperse dyes by partial least squares (PLS) analysis and compared to previously published MLR (multiple linear regression), MTD (minimum steric difference) and CoMFA (comparative molecular field analysis) results. Calculated 0D, 1D and 2D structural dye features were correlated to their affinity for cellulose by PLS. A robust model (R2X(cum) = 0.617, R2Y(cum) = 0.959, Q2(cum) = 0.953) with predictive power was obtained from these correlations. Better statistical results were achieved in the PLS model, in comparison to the previous MLR, MTD and CoMFA results, but the three-dimensional models obtained by CoMFA gave more information on the dye-cellulose specific interactions.

not available

Classification algorithms are proposed based on information entropy. It is studied the molecular classification of anti-human immunodeficiency virus thiocarbamates. The 62 thiocarbamates (TCs) are classified by their structural chemical properties. Many classification algorithms are based on information entropy. An excessive number of results appear compatible with the data and suffer combinatorial explosion. However, after the equipartition conjecture one has a selection criterion. According to this conjecture, the best configuration of a flowsheet is that in which entropy production is most uniformly distributed. The structural elements of an inhibitor can be ranked according to their inhibitory activity in the order: B1/2 > R > R1 > R2 substitution. In TC 17, B1/2 = B1, R = 4-CH3 and R1 = R2 = H; its associated vector is unary. The TC 17 is selected as a reference. In some TCs B1/2 = B1, in some others B1/2 = B2. The analysis is in qualitative agreement with other classification taken as good based on k-means clustering. Program MolClas is a simple, reliable, efficient and fast procedure for molecular classification, based on the equipartition conjecture of entropy production. The structural elements allow the periodic classification of the TCs. A validation is performed with an external property, cytoprotection activity, not used in the development of the table.

Optimized geometry and the corresponding electronic structure, vibrational frequencies and thermodynamic properties of cyclopropylmethoxychlorocarbene (cpmcc), 3- cyclopropylmethoxy-3-chlorodiazirine have been calculated using ab initio methods DFTB3LYP with 6-311++G** basis set. Results show that cpmcc is transition state with a first order TS saddle point. The displacement matrix of the negative mode of vibration of the TS specie shows that the reaction path follows in the direction of the elimination of the CO group which is consistent with the mechanism proposed upon experimental data. Calculations were also carried out for reactants and products at the same levels of theory. Nuclear quadrupole coupling constants (NQCC), χ, and asymmetry parameter, η, of the 2H, 35Cl nuclei have been calculated for reactants, transition states and products.

There are many enantioselective reactions of organolithium to imines described in a very different conditions. In this work, we constructed from experimental outcomes large Complex Network, which may be used to perform datamining and quantitatively describe changes in reaction variables that determine the enantiomeric excess and configuration of the stereogenic centre formed in product.

Thiiranium heterocycles play an important role in a biocatalytic processes of cells. Usually formation of thiiranium ions are known to proceed by the electrophilic additions of sulfenylhalides to a substituted olefins. We focused attention on the electrophilic addition reaction of methylsulfenyl chloride to the propene. In our work this reaction have been modeled using Ab-initio methods at the MP2/6-31+G(d,f) level of theory to look into the mechanism of the reaction and to explain how the regioselectivity of the reaction is controlled. Calculations of the intrinsic reaction coordinate on the minimum energy pathway revealed the stepwise mechanism for the addition reaction.

Optimized geometry and the corresponding electronic structure and thermodynamic properties of cyclopropylmethoxychlorocarbene (cpmcc), 3-cyclopropylmethoxy-3- chlorodiazirine and their -N2 and –CO elimination and consequent rearrangement products, cyclopropylmethoxyfluorocarbene (cpmfc), 3-cyclopropylmethoxy-3-fluorodiazirine and its transition state and cyclopropylmethoxyhydrocarbene (cpmhc), 3-cyclopropylmethoxy-3- hydrodiazirine and its transition state have been calculated using ab initio methods DFTB3LYP with 6-311++G** basis set. The effect of substitutions was investigated on thermodynamic properties of conversion of 3-cyclopropylmethoxy-3-chloro (flouro or hydro) diazirine to different products. Also, nuclear magnetic resonance chemical shifts have been calculated for reactant, transition state and product with various substitutions.

The reaction pathways for the addition of OH- ion to cyclobutane-1,2-dione I are calculated by density functional theory procedures [B3LYP/6-31+G(d,p)]. Initially, I undergoes attack of the nucleophile, in this case OH- ion, at one of the two equivalent carbonyl carbon atoms leading to formation of a tetrahedral intermediate followed by rearrangement reactions. Density functional theory method (B3LYP) with basis set (6-31+G (d,p) are used to investigate the addition of OH- (hydrated) to the hydrated species of I. The most likely pathway consists in a ring contraction of the tetrahedral intermediate, formed from addition of OH– to I, leading to 1-cyclopropan-1-carboxylic acid.