Determination of the reactivity parameters for the copolymerization of butyl acrylate with vinyl acetate

The composition of vinyl acetate–butyl acrylate copolymers obtained with batch emulsion polymerization have been studied by ¹H-NMR. Using the integrated copolymerization Meyer–Lowry equation, the apparent reactivity ratios of the two monomers were calculated as 10.67 for r₁, the reactivity ratio of butyl acrylate (BA), and 0.024 for r₂, the reactivity ratio of vinyl acetate (VAC). These results were compared with those obtained by other methods.     

Preparation and characterization of a viscosity index improver for naphthenic and paraffinic base oils

Copolymers of -methyl styrene and 2-ethylhexyl acrylate were prepared in a benzene solution. The presence of the copolymers were confirmed by solubility, IR and NMR tests. The molecular weight and the polydispersity of the polymers were estimated by GPC. The copolymers obtained were blended with paraffinic and naphthenic base oils. The viscosity, the viscosity index (VI) the Q value as well as the stability to shear and oxidation were obtained for these blends. The results are compared with the results obtained with an oil blend containing a commonly used high temperature additive. Two of the copolymers obtained have shown to be good alternatives for specific applications.Presented at the Symposium, 76^th CSC Congress, Sherbrooke, Quebec, May 30–June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65^th birthday.     

Emulsion polymerization of styrene. III. Effect of Ti(III) and Cl(1) on the polymerization of styrene initiated by potassium persulfate

The emulsion polymerization of styrene initiated by potassium persulfate catalyzed by Ti⁺³ ions was studied. Two sources of Ti⁺³ ions were used: the titanium trichloride and titanium sulfate. It was found that the titanium ions used in conjunction with potassium persulfate decrease both the reaction rate and the average molecular weight. An even greater drop of reaction rate was noted when chlorine anions (TiCl₃) were present. The presence of these ions had a stabilizing effect on the polydispersity.     

Identification and Preliminary Structure-Activity Relationship Studies of 1,5-Dihydrobenzo[e][1,4]oxazepin-2(3H)-ones That Induce Differentiation of Acute Myeloid Leukemia Cells In Vitro

Acute myeloid leukemia (AML) is the most aggressive type of blood cancer, and there is a continued need for new treatments that are well tolerated and improve long-term survival rates in patients. Induction of differentiation has emerged as a promising alternative to conventional cytotoxic chemotherapy, but known agents lack efficacy in genetically distinct patient populations. Previously, we established a phenotypic screen to identify small molecules that could stimulate differentiation in a range of AML cell lines. Utilising this strategy, a 1,5-dihydrobenzo[e][1,4]oxazepin-2(3H)-one hit compound was identified. Herein, we report the hit validation in vitro, structure-activity relationship (SAR) studies and the pharmacokinetic profiles for selected compounds.     

Hemi(piperazinediium) hexaaqua­aluminium(III) bis­(sulfate) tetrahydrate: a new double aluminium sulfate salt

Piperazinium aluminium sulfate decahydrate, (C₄H₁₂N₂)_0.5[Al(H₂O)₆](SO₄)₂·4H₂O, exhibits a crystal structure built from isolated [Al(H₂O)₆]³⁺, SO₄²⁻, C₄H₁₂N₂²⁺ and H₂O units connected by a complex hydrogen‐bond network. The title compound shows strong similarities to many double alumin­ium sulfates, such as alums and Tutton's salts. However, since its structure is not derived directly from that of these compounds, it is assumed to be a new structure type.