Unlike surfactant–polymer interactions of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate with water-soluble polymers

Single and mixed micelle formation by sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) and their mixtures in pure water and in the presence of water-soluble polymers such as Synperonic 85 (triblock polymer, TBP), hydroxypropylcellulose (HPC), and carboxymethylcellulose sodium salt (CMC) were studied with the help of conductivity, pyrene fluorescence, cyclic voltammetry, and viscosity measurements. Conductivity measurements showed a single aggregation process for pure surfactants and their mixtures both in pure water as well as in the presence of water-soluble polymers. Triple breaks corresponding to two aggregation processes for SDS, SDBS, and their mixture in the presence of TBP were observed from fluorescence measurements. The first one demonstrated the critical aggregation process due to the adsorption of surfactant monomers on TBP macromolecule. The second one was attributed to the participation of surfactant–polymer aggregates formed at the first one, in the micelle formation process. The aggregation number ( N _agg) of single and mixed micelles and diffusion coefficient ( D) of electroactive probe were computed from the fluorescence and cyclic voltammetry measurements, respectively. Both parameters, along with the viscosity results, indicated stronger SDS–polymer interactions in comparison to SDBS–polymer interactions. Mixed surfactant–polymer interactions showed compensating effects of both pure surfactants. The nature of mixed micelles was found to be ideal in all cases, as evaluated by applying the regular solution and Motomura's approximations.     

Synthesis and Anticancer, Antiinflammatory,and Analgesic Activity Evaluation of Some Sulfa Drug and Acridine Derivatives

Summary.  Various sulfa drugs were condensed with 4-isothiocyanato-4-methyl-2-pentanone at pH∼3–5 by refluxing in methanol to give various substituted mercaptopyrimidines. On condensation with 9-chloro-2-substituted or -unsubstituted acridines, sulfathiazole gave the corresponding condensed products. N-Ethylaminoadenosine reacted with 9-chloroacridine to the coupled product. Condensation of sulfathiazole with 9-isothiocyanato-2,4-substituted or -unsubstituted acridines afforded the corresponding condensed compounds. The structures of all synthesized compounds were confirmed by spectroscopic methods. Anticancer, antiinflammatory, and analgesic activities of all compounds were investigated. Received November 18, 1999. Accepted (revised) January 12, 2000     

Effect of gamma radiation on organic ion exchangers

Effects of gamma radiation on indigenous strong cation and anion exchange resins have been studied in HCl medium up to a dosage of 3600 kGy. The ion exchange capacities of cation and anion exchangers decreased by around 20% at 2400 kGy of absorbed dose. Decrease in salt-splitting capacity and total exchange capacity for both cation and anion exchangers were comparable up to 2400 kGy. Above 2400 kGy, a marginal loss in the capacity was observed for cation exchangers whereas a drastic reduction was noticed for the anion exchangers. The distribution coefficients for zirconium, antimony and cobalt, measured in HCl medium, did not change significantly for 2400 kGy of absorbed dose. Crushing strength and moisture retention capacity did not exhibit any specific trend with the absorbed dose.     

Oxidation of a P−C Bond under Mild Conditions

The reactivity of phosphenium dication [(Ph₃P)₂C‐P‐NiPr₂]²⁺, 1²⁺ , towards pyridine N‐oxide (O‐py) has been investigated. The resulting oxophosphonium dication [(Ph₃P)₂C(NiPr₂)P(O)(O‐py)]²⁺, 2²⁺ , was surprisingly stabilized by a less nucleophilic O‐py ligand instead of pyridine (py). This compound was then identified as an analogue of the elusive Criegee intermediate as it underwent oxygen insertion into the P?C bond through a mechanism usually observed for Baeyer–Villiger oxidations. This oxygen insertion appears to be the first example of a Baeyer–Villiger oxidation involving O‐py.     

A Well‐Defined Aluminum‐Based Lewis Acid as an Effective Catalyst for Diels–Alder Transformations

A catalytically active aluminum‐based system for Diels–Alder transformations is reported. The system was generated by mixing a β‐diketiminate‐stabilized aluminum bistriflate compound with Na[BAr^Cl₄] (Ar^Cl=3,5‐Cl₂C₆H₃). Solid‐state analysis of the catalytic system reveals a unique structure incorporating a two‐dimensional coordination polymer. According to the experimental results obtained from several Diels–Alder transformations, the aluminum‐based system appears to be a more practical and more robust alternative to the recently reported compounds based on carbon and silicon cations.     

Constituents of Cissus quadrangularis

Two new iridoids 6-O-[2,3-dimethoxy]-trans-cinnamoyl catalpol (1) and 6-O-meta-methoxy-benzoyl catalpol (2) along with a known iridoid picroside 1 (3), two stilbenes quadrangularin A (4) and pallidol (5), quercitin (6), quercitrin (7), beta-sitosterol (8) and beta-sitosterol glycoside (9) were isolated from Cissus quadrangularis Linn. The compounds 3 and 7 are first reported from this plant. The structures were elucidated by analysis of their spectroscopic data and by direct comparison with literature. This is the first reported occurrence of iridoids in C. quadrangularis.     

Capillary electrophoretic-ultraviolet method for the separation and estimation of zineb, maneb, and ferbam in food samples

A simple and sensitive capillary electrophoretic method with ultraviolet detection has been developed for the separation and determination of ferbam [iron(III)-dimethyldithiocarbamate], maneb [manganese(II)-ethylenebisdithiocarbamate] and zineb [zinc(II)-ethylenebisdithiocarbamate], in borate buffer, after their acidic decomposition and complexation with CDTA (trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid monohydrate), as CDTA-metal complexes of Fe+3, Mn +2, and Zn+2. The determination is dependent on the pH and the nature of the buffer solutions. In this method, the detection limit (signal-to-noise ratio = 3) is 0.0013, 0.0022, and 0.0023 mM for ferbam, maneb, and zineb, respectively. The relative standard deviation for the analysis of 1 mM of each was found to be 1.5 +/- 0.2%. The method was successfully applied for the analysis of red beans and grain samples spiked with ferbam, maneb, and zineb. The applicability of capillary electrophoresis as a useful tool for the simultaneous determination and analysis of ferbam, maneb, and zineb is demonstrated.     

Glycerol Dehydratases: Biochemical Structures,Catalytic Mechanisms,and Industrial Applications in 1,3-Propanediol Production by Naturally Occurring and Genetically Engineered Bacterial Strains

To date, two types of glycerol dehydratases have been reported: coenzyme B₁₂-dependent and coenzyme B₁₂-independent glycerol dehydratases. The three-dimensional structure of the former is a dimer of αβγ heterotrimer, while that of the latter is a homodimer. Their mechanisms of reaction are typically enzymatic radical catalysis. Functional radical in both the glycerol dehydratases is the adenosyl radical. However, the adenosyl radical in the former originates from coenzyme B₁₂ by homolytic cleavage, and that in the latter from S-adenosyl-methionine. Until some years ago, Clostridium butyricum VPI 1718 was the only microorganism known to possess B₁₂-independent glycerol dehydratase, but since then, several other bacteria with this unique capability have been identified. This article focuses on the glycerol dehydratases and on 1,3-propanediol production from glycerol by naturally occurring and genetically engineered bacterial strains containing glycerol dehydratase.