Preparation and Evaluation of Some Terpolymers as Lube Oil Additives

In the present work, some polymeric additives were prepared to use as viscosity index improvers and pour point depressants for lube oil via copolymerization of hexadecylacrylate and dodecylacrylate with styrene. Structure of the prepared compounds was confirmed by infrared spectroscopy and nuclear magnetic resonance. The molecular weights of the prepared copolymers were determined by using gel permeation chromatograph. The efficiency of the prepared terpolymers as viscosity index improvers and pour point depressants for lube oil was investigation. It was found that all the prepared terpolymers are effective as viscosity index improvers and pour point depressants. The viscosity index of the prepared terpolymers increases with increasing the concentration of the additives and increases by increasing the percentage of hexadecylacrylate until 70%. The best result for viscosity index of the prepared terpolymers is when the percentage of styrene is 10%. The pour point of the prepared compound decreases with decreasing concentration of additive used.     

Surface Active and Thermodynamic Properties in Relation to the Demulsification Efficiency for Some Ethoxylated Derivatives of Alkyldiamines and Polyalkylenepolyamines

In this work, nine monostearic esters of ethoxylated dialkyle-amine (group I) and ethoxylated polyalkylenepolyamine (group II) nonionic surfactants were prepared and characterized by FTIR spectroscopy and nitrogen content. The 1,4-diaminobutane (DAB), 1,6 diamino hexane (DAH), 1,8-diamino-octane (DAO), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) were ethoxylated at 50, 100, 150 ethylene oxide units individually. The ethoxylated products of (group I) reacted with stearic acid to give the monostearate products. The surface tension of the prepared compounds were measured at 25°C and 60°C. The thermodynamic parameters of micellization and adsorption were also calculated. The surface active properties, such as critical micelle concentration (CMC), maximum surface excess concentration (Γ_max), effectiveness of surface tension reduction (π_cmc), and minimum area per molecule at the aqueous solution-air interface (A_min), have been calculated. The surface active and thermodynamic properties of the prepared compounds were correlated to their chemical structure. It was found that CMC decreases when increasing the molecular weight of polyethylene oxide units. Furthermore, the data show that the synthesized surfactants favor adsorption than micellization, so that they can be used as demulsifiers for waxy crude oil emulsion (BSW 18%). In this respect, the demulsification test was carried out and the results of demulsification efficiency were correlated to the chemical composition of the investigated compounds. Some factors that affect the demulsification efficiency were also considered such HLB, concentration and time. The maximum demulsification efficiency (100%) was obtained by DAOE_150-M and TEPAE₁₅₀ at 60 and 45 minutes (300 ppm), respectively.     

Potentiometric Titration of Na2HAsO4, NaPO3, Na4P2O7, and their Binary Mixtures in NaNO3 Melt at 350°C Using a Novel Solid State Glass/TiO2 as pH Indicator Electrode

A solid‐state glass/TiO₂ electrode was fabricated using a transparent conductive titanium oxide film on a glass substrate. The coating of the glass substrate was achieved by a novel simple chemical vapor deposition (CVD) procedure. This electrode can be used as an indicator electrode in potentiometric acid‐base titration. This electrode behaves reversibly and responds to the oxide ion concentration in molten NaNO₃ · Na₂HAsO₄, NaPO₃, Na₄P₂O₇, and their binary mixtures were potentiometrically titrated with Na₂O₂ as titrants in molten NaNO₃ at 350°C, using the above mentioned indicator electrode.     

Trichloroisocyanuric Acid,as an Industrial Chemical,Promotes Transthioacetalization of Diacetals of 2,2-Bis (Hydroxymethyl)-1,3-propanediol and Cleavage of Thioacetals

Trichloroisocyanuric acid has been used as a mild, efficient, and new catalyst for transthioacetalization of diacetals of 2,2-bis (hydroxymethyl)-1,3-propanediol in CH 2 Cl 2 at room temperature. A clean, easy, and general method for efficient deprotection of thioacetals to their corresponding carbonyl compounds using trichloroisocyanuric acid/silica gel and water system also is described.     

4-Aminophenyl Diphenylphosphinite (APDPP) as a Heterogeneous and Acid Scavenger Reagent for Thiocyantion or Isothiocyanation of Alcohols and Protected Alcohols

4-Aminophenyl diphenylphosphinite (APDPP) as a heterogeneous phosphinite reagent is used for the efficient conversion of alcohols, trimethylsilyl- and tetrahydropyranyl ethers, α -hydroxy phosphonates, and α -trimethylsilyloxyphosphonates to their corresponding thiocyanates or isothiocyanates in the presence of Br ₂ and NH ₄ SCN.     

2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO), N-Bromosuccinimide (NBS) and Bromine as Efficient Catalysts for Dithioacetalization and Oxathioacetalization of Carbonyl Compounds and Transdithioacetalization Reactions

The use of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO), N-bromosuccinimide (NBS), and bromine as efficient catalysts for conversion of carbonyl compounds to their cyclic and acyclic dithioacetals and 1,3-oxathiolanes under mild reaction conditions are described. These catalysts are also used for efficient transdithioacetalization of acetals, diacetals, ketals, acylals, enamines, hydrazones, and oximes with high yields in the presence of thiols.     

The response of selected isomers of B80 buckyball toward NH3 adsorption: a density functional theory investigation

Density functional theory calculations at the B3LYP/6-31G(d) and B3LYP/6-31+G(d) levels were carried out for the adsorption of NH₃ on three symmetric isomers of B₈₀ {C ₁, T _h, I _h}. To investigate the binding features of B₈₀ isomers with NH₃, different studies including the structural and electronic parameters, the ¹⁴N electric field gradient tensors and the atoms in molecules (AIM) properties were considered. The calculated parameters by these investigations can be used as powerful tools to find out some of the unknown aspects of electronic structures of the boron buckyball and its isomers. According to previous studies, boron buckyball as an amphoteric and a hard molecule has two distinct reactive sites defined as cap and frame which act as an acid and a base, respectively. Regarding the obtained results in this study, all the isomers had the same exposure when NH₃ molecule reacted with the external wall of B₈₀. For instance, the stability of N–B bond in the cap site was significantly more than the stability of N–B bond in the frame. Moreover, the adsorption of NH₃ on frame site showed a considerable reduction in HOMO–LUMO energy gap. According to AIM theory, an electrostatic nature was observed for N–B interaction. Concerning the selected isomers of buckyball, the capability of the NH₃–B₈₀ complexes to localize electron at the N–B bond critical points depend on the reaction sites significantly. In general, ¹⁴N nuclear quadruple coupling constants and asymmetry parameter reveal a remarkable effect of NH₃ adsorption on electronic structure of the B₈₀.     

Silphos [PCl3− n (SiO2) n ]: A Heterogeneous Phosphine Reagent for the Regioselective Synthesis of vic-Haloalcohols

Silphos as a silica-based phosphine [PCl_3?n (SiO₂) _n ] provides a practical method for the conversion of epoxides to vic-haloalcohols in the presence of molecular bromine, iodine, or N-halosuccinimides (NXS, X = Cl, Br, I) in CH₃CN or under solvent-free conditions at r.t. The simple filtration of heterogeneous Silphos oxide from the reaction mixture affords the pure vic-haloalcohols with excellent yields.     

Multiclass analysis on repaglinide,flubendazole, robenidine hydrochloride and danofloxacin drugs

The drugs under study; repaglinide (Repag), flubendazole (Flu), robenidine hydrochloride (Roben) and danofloxacin (Dano) are antidiabetic, anthelmintic, anticoccidial, and antibiotic drugs. In the present study, they are investigated using electron impact mass spectral (EI-MS) fragmentation at 70 eV, in comparison with thermal analyses measurements (TGA/DrTGA and DTA) and molecular orbital calculation (MO). Semi-empirical MO calculation, AM1 procedure, has been carried out on Repag, Flu, Roben and Dano both as neutral molecules (in TA) and the corresponding positively charged species (in MS). The calculated MO parameters include bond length, bond order, charge distribution on different atoms and heat of formation. The fragmentation pathways of Repag, Flu, Roben and Dano in EI-MS led to the formation of important primary and secondary fragment ions. The mechanism of formation of some important daughter ions can be illuminated from comparing with that obtained using mass spectrometer through the accurate mass measurement determination. The MO provides a base for fine distinction among sites of initial bond cleavage and subsequent fragmentation of drug molecules in both thermal analysis and MS techniques. The activation thermodynamic parameters, such as, (activation energy E¹), (enthalpy ΔH¹), (entropy ΔS¹) and (Gibbs free energy ΔG¹) are calculated from the DrTGA curves using Coats–Redfern and Horowitz–Mitzger methods.     

Chiral Separation of 4-Iminoflavan Derivatives on Several Polysaccharide-Based Chiral Stationary Phases by HPLC

The HPLC enantiomeric separation of seven 4-iminoflavans was successfully accomplished in the normal phase mode using six polysaccharide-based chiral stationary phases namely, Chiralcel^®OD-H, Chiralcel^®OD, Chiralcel^®OJ, Chiralpak^®AD, Chiralpak^®IA and Chiralpak^®IB under normal and polar organic phase modes. The resolution depended on nature and concentration of alcoholic modifier. The results demonstrate clearly that the chromatographic system based on the coated and immobilized type Chiralpak^®IB and Chiralcel^®OD-H CSPs provide a powerful analytical tool for enantiomeric separation of all the 4-iminoflavans used in this study.