a spectrophotometric method is used to determine the acidity constants of some derivatives of 9,10-anthraquinone in binary methanol-water mixtures at 25 °c. there is a linear inverse relationship between pka of all acids and the mole fraction of methanol in the mixed solvent. the influence of substituents in the molecular structure on the ionization constants is discussed.

in theoretical chemistry, molecular structure descriptors are used to compute properties of chemical compounds. among them wiener, szeged and detour indices play significant roles in anticipating chemical phenomena. in the present paper, we study these topological indices with respect to their difference number.

in this paper, a new molecular-structure descriptor, the general sum–connectivity co–index  is considered, which generalizes the first zagreb co–index and the general sum–connectivity index of graph theory. we mainly explore the lower and upper bounds in termsof the order and size for this new invariant. additionally, the nordhaus–gaddum–type resultis also represented.

there is considerable confusion concerning the structure and synonymity of macroscopic sarcocysts in goats. in the present work, ultrastructural and molecular study on fat and thin macrocysts of sarcocystis isolated from naturally infected goats were investigated. two forms of macrocystic sarcocysts were collected from fresh oesophagus, diaphragm, skeletal muscles and heart of slaughtered goats...

the dispersibility of graphene is modeled as a mathematical function of the molecular structure of solvent represented by simplified molecular input-line entry systems (smiles) together with the graph of atomic orbitals (gao). the gao is molecular graph where atomic orbitals e.g. 1s1, 2p4, 3d7 etc., are vertexes of the graph instead of the chemical elements used as the graph vertexes in the tra...

In this study, we theoretically investigated Methyl hydrazinecarbodithioate by quantum chemical calculations for geometry optimization, vibration frequencies, and electronic structure parameters. The geometry optimization by DFT, ab initio MP2 method and the frequency calculation by DFT method was performed at the highest available Pople style 6-311G++(3df,3pd) basis set level. The semi-emp...

An important property that has been extensively studied in quantitative structure activityrelationship (QSAR) is the chromatographic retention index. QSAR study is suggested for theprediction of retention index of alkanes and alkenes compounds. Modeling of the retention indexof alkanes and alkenes compounds as a function of molecular structures was established bydifferent chemometrics methods. ...

A new homologous series of linear aliphatic polyesters, such as poly (cis-2- butenylene carboxylate)S, PBms (m is the number of methylene groups in the acid component, m=2-8 have been synthesized by direct polyesterification reactions in anisole, as solvent. FT-IR, 400 MHz H- NMR, C-NMR and elemental analysis were used to establish the structure of polyesters. Molecular weight distributi...