Graft polymerization of acrylic monomers onto starch fractions. I. Effect of reaction time on grafting methyl methacrylate onto amylose

A study was made of the ceric-ammonium-nitrate-initiated graft polymerization of methyl methacrylate (MMA) onto a lineal fraction of starch (amylose). Grafting yields were determined by extraction with appropriate solvents: 1,2-dichloroethane for homo-PMM, and 0.5N NaOH for ungrafted amylose. Percent grafting was calculated by acid hydrolysis with 1N HCl. Molecular weights of PMMA side chains were determined by gel permeation-chromatography. Grafting efficiencies ranged from 72 to 83%, grafting, from 190 to 271%, and frequency of attachment of side chains, from 900–1250 glucose units per chain. The results observed are discussed.     

Liquid-liquid extraction of tungsten(VI) with mesityl oxide application to an alloy steel

A new and simple method has been developed for the rapid extraction of tungsten(VI) with mesityl oxide. Quantitative extraction occurs from solutions 1M in hydrochloric acid and 12M in lithium chloride (as the salting-out agent) with 75% mesityl oxide in isobutyl methyl ketone. Tungsten is finally determined photometrically as the thiocyanate complex in the aqueous phase. Tungsten-(VI) can be extracted and determined satisfactorily in the presence of several elements. The method is shown to be applicable to an alloy steel.     

Mixed ligand extraction of cobalt(II) by thenoyltrifluoroacetone and triphenylphosphine or triphenylarsine oxides in chloroform

Extraction of Co(II) from perchlorate aqueous media by mixtures of thenoyltrifluoroacetone and triphenylarsine oxide or triphenylphosphine oxide in chloroform has been studied. It is found that the presence of these oxides enhances the extraction of Co(II). Synergic factors and formation constants were calculated and interpreted in the light of the electron donating properties of these oxides.     

Adduct of Triphenylphosphine Oxide and Sulfuric Acid: Synthesis and Structure

Adduct of triphenylphosphine oxide and sulfuric acid was synthesized by reacting arenesulfonic acids with triphenylphosphine oxide (1 : 2) in the presence of the moisture of air. According to the X-ray diffraction data, the phosphorous atom has a distorted tetrahedral coordination. The sulfuric acid molecule is disordered over two sites and is linked with two triphenylphosphine oxide molecules through hydrogen bonds.     

Stable 1,6-Diionic Phosphorus Betaines Derived from Electron-Deficient Acetylenic Compounds

The addition of triphenylphosphine to methyl propiolate, ethyl propiolate, or ethynyl methyl ketone in the presence of a strong NH-acid, such as 5-nitro-2,4-dihydro-3 H -1,2,4-triazol-3-one, leads to stable 1,6-diionic organophosphorus compounds in excellent yields.     

Traditional Morita-Baylis-Hillman reaction of aldehydes with methyl vinyl ketone co-catalyzed by triphenylphosphine and nitrophenol

In the Morita-Baylis-Hillman reaction of aldehydes with methyl vinyl ketone (MVK), we found that in the presence of a catalytic amount of phenol, the Lewis base triphenylphosphine can effectively promote the reaction to give the corresponding normal Morita-Baylis-Hillman adducts in good yields. The mechanism has been investigated by 31P NMR spectroscopy. The solvent and substituent effects were also examined.     

Synergic extraction of dioxouranium(VI) with di (2-ethylhexyl) dithiophosphoric acid and triphenylphosphine oxide in benzene

Synergic extraction of dioxouranium (VI) from aqueous solutions with di (2-pethylhexyl) di thi ophosphoric acid (HEhdtp) and triphenylphosphine oxide (TPPO) in benzene has been investigated. Slope analysis of the extraction results indicates the composition of mixed species formed in the organic phase as UO₂ (Ehdtp)₂TPPO. The extraction constant and formation constant of the mixed species has been calculated.     

The extraction of lead iodide by methyl iso-propyl ketone

A method is proposed for the isolation of lead by solvent extraction. When solutions of lead ions are treated with excess potassium iodide and hydrochloric acid (5 %), lead iodide is extracted quantitatively by methyl iso-propyl ketone. Employing a preliminary extraction with methyl iso-propyl ketone after conditioning the aqueous solution with ammonium thiocyanate and hydrochloric acid, practically all interferences are eliminated (except Cd and Ru).     

Studies on the extraction of chromium(VI) by ketones

A study of the extraction of chromium(VI) from aqueous media by ketones was made. Extraction of chromium was found to be most efficient from aqueous hydrochloric acid solutions. A mechanism for the extraction of chromium(VI) from aqueous hydrochloric acid solutions by methyl isobutyl ketone is proposed involving the formation of a receptor in the organic phase, the exchange of the chloride ion of the receptor for the anionic chromium(VI) species of the aqueous phase, and the solvation of the extracted chromium species. The differences in the abilities of various ketones to extract chromium(VI) from aqueous hydrochloric acid solutions, and the differences in the extraction of chromium (VI) from various aqueous acids by methyl isobutyl ketone are attributed to the differences in the formation of receptors.     

Polarographic determination of phosphorus

A method has been developed for the determination of phosphorus, as phosphate, by means of the catalytic polarographic wave for the reduction of hydrogen peroxide in the presence of Mo(VI). This reduction is combined with the previous formation and extraction of 12-molybdophosphoric acid. Depending on the extractant chosen, ethyl acetate or methyl isobutyl ketone, the determination limit is 2.3 or 3.1 mug l . respectively. The procedure has been applied to certified steel samples with good results.     

Extraction and spectrophotometric determination of titanium(IV) with alizarin and fluoride

The characteristics of the mixed-ligand titanium(IV)-fluoride-alizarin complex, including the optimum conditions of formation and extraction into methyl isobutyl ketone, are described. A simple and sensitive procedure for spectrophotometric determination of titanium has been developed. At pH 9.5-10.3 titanium reacts with alizarin in the presence of fluoride to form a red-violet complex that is completely extractable into methyl isobutyl ketone, and has its absorption maximum at 513 nm. The molar absorptivity at 513 nm is 7.0 x 10(4)l.mole(-1).cm(-1). Beer's law is obeyed up to 22 mug of titanium in 30 ml of solution. The method has been used for the determination of titanium in an oxide mixture and aluminium alloy samples.     

Cotton‐hydrogel composite for improved wound healing: Antimicrobial activity and anti‐inflammatory evaluation—Part 2

Infection is one of the major risk factors for the development of chronic wounds. Antimicrobial wound dressing has been pointed out as a viable option for the prevention and treatment of wound infections. Thus, we developed a composite material based on cotton textile substrates functionalized with cyclodextrin‐hydroxypropyl methyl cellulose‐based hydrogel. The composites' ability to encapsulate and release gallic acid (antimicrobial phenolic acid) was evaluated, as well as their mechanical properties and antimicrobial and anti‐inflammatory capacity. All composites were able to retain gallic acid in their structure, with similar loading profile. The presence of gallic acid on composites was confirmed by FTIR and TGA. Composites storage moduli was reduced by the presence of gallic acid. The results suggest a straight relation between the swelling ability and gallic acid drug delivery profile. The drug delivery mechanism, of the developed composites, was mainly controlled by Fickian diffusion, based on the experimental data fitting to the Peppas‐Sahlin model. Gallic acid antimicrobial and anti‐inflammatory properties were transferred to the composite materials. According to the results, the developed composites can be applied on the prevention or treatment of chronic wounds.     

Synthesis of Highly Functionalized gamma-Butyrolactones from Activated Carbonyl Compounds and Dimethyl Acetylenedicarboxylate

A triphenylphosphine-catalyzed cyclization of alpha-keto esters, alpha-keto nitriles, or alpha,alpha,alpha-trifluoroacetophenone with dimethyl acetylenedicarboxylate is reported to produce highly functionalized alpha,beta-unsaturated gamma-butyrolactones in moderate yields. Thus treating a mixture of methyl 4-nitrophenylglyoxylate and dimethyl acetylenedicarboxylate with 20 mol % of triphenylphosphine afforded 5,5'-disubstituted 3-methoxy-4-(methoxycarbonyl)-2(3H)-furanone in 94% yield. In the reaction of alpha-keto esters R(1)COCOOMe, an electron-withdrawing R(1) substituent is required for satisfactory reactivity. On the other hand, electron-donating R(1) substituents give higher yields with alpha-keto nitriles R(1)COCN. Another electron-deficient carbonyl compound, alpha,alpha,alpha-trifluoroacetophenone, gave the corresponding lactone in good yield. The use of an alpha-hydroxy ketone as an electrophilic carbonyl compound with more than 1 equiv of triphenylphosphine produced dihydrofuran derivatives. One equivalent of triphenylphosphine oxide was obtained as a major product. An intramolecular Wittig reaction is proposed as a reaction mechanism.     

Determination of iron in biological material by substoichiometric isotopic-dilution analysis

Iron is determined in biological material by wet oxidation, in the presence of (59)Fe tracer, extraction of iron(III) chloride into isopropyl methyl ketone, stripping with nitric acid, and substoichiometric separation of the Fe-EDTA complex on a cation-exchanger. The precision is good and the method has been applied to analysis of standard kale and blood.     

Determination of antimony in rocks and sulphide ores by flame and electrothermal atomic-absorption spectrometry

Atomic-absorption methods for determination of antimony at mug/g levels in rocks and sulphide ores by flame atomization (FAA) and electrothermal atomization (ETAA) have been described. The FAA method involves the separation of antimony from matrix elements by extraction as the iodide into methyl isobutyl ketone containing tri-n-octylphosphine oxide, from dilute hydrochloric acid solution, followed by direct aspiration of the extract into an air-acetylene flame. If necessary, antimony is first separated from copper and lead by co-precipitation with hydrous ferric oxide from ammoniacal medium and by precipitation of lead as lead sulphate. The ETAA method involves co-precipitation of antimony with hydrous ferric oxide followed by dissolution of the precipitate in dilute nitric acid, mixing with nickel solution as releasing agent, and ETAA measurement by use of a tungsten strip atomizer.     

Synthesis of Substituted Terphenyl Derivatives

Several substituted terphenyl derivatives were prepared following two synthetic routes with five steps. Condensation of 4‐amino‐3‐bromo‐benzotrifluoride with 4‐(methylthio) phenyl boronic acid in the presence of sodium carbonate and palladium triphenylphosphine in toluene gave 4‐amino‐3‐(4‐methylthiophenyl)‐benzotrifluoride. Treatment of this compound with osmium tetroxide in the presence of 4‐methyl morpholine‐N‐oxide yielded the corresponding sulfone, which was converted into the iodo derivative using sodium nitrite. The iodo derivative thus obtained was treated first with propylmagnesium chloride and triethylborane and subsequently with hydroxylamine‐O‐sulfonic acid to furnish the target compounds.     

Joint QTAIM and Hirshfeld study of the sigma and pi charge distribution and electron delocalization in carbonyl compounds: a comparative study with the resonance model

Atomic charges and delocalization indexes (DIs) for a series of carbonyl compounds comprising dimethyl ketone, acetaldehyde, acetic acid, methyl acetate, acetamide, methyl vinyl ketone, divinyl ketone, and benzoic acid were studied using two different atomic partitionings: the QTAIM and the Hirshfeld (stockholder) scheme. The resonance model, traditionally employed to explain the reactivity of these compounds, is not in line with the total atomic charges and DIs calculated by both methodologies. However, the resonance model is supported to some extent by the pi charges and pi DIs calculated by both schemes, but the calculated values indicate that the pi population delocalizes only to a small degree. Although the absolute values of QTAIM and stockholder atomic charges are significantly different, the pi charges and the values of the DIs show similar trends for all the atoms and molecules of this study; this is especially the case for the pi DIs. A study of the electron density on the level of a single MO performed for CO, H2CO, F2CO, and H2CS reveals that the differences in the atomic sigma charges computed with both partitionings can be traced back to their different treatment of interatomic regions.     

Electrochemical oxidation of tertiary phosphines in the presence of camphene

Anodic oxidation of tertiary phosphines (tripropyl-, tributyl-, and triphenylphosphine) in the presence of a bicyclic alkene (camphene) on a platinum and a glassy carbon electrodes was studied. For the first time the voltammetric characteristics of the process of camphene anodic oxidation were obtained. The electrochemical reactions with alkyl and aromatic phosphine were found to be dissimilar. The results of preparative electrooxidation of trialkylphosphines showed that in the course of electrolysis the tertiary phosphine cation-radicals generated on the anode enter into two concurrent reactions: (1) with the parent phosphine to form eventually trialkylphosphonium salts and trialkylphosphine oxides presumably as complex compounds and (2) with camphene to form trialkylcamphenylphosphonium salts and probably phosphonium salts with a monocyclic substituent. Preparative electrochemical oxidation of triphenylphosphine in the presence of camphene affords almost exclusively either triphenylphosphine oxide (in the experiment with platinum anode) or the triphenylphosphine oxide complex with perchloric acid (at the electrolysis on a glassy carbon anode).     

Extraction of protactinium from mineral acid-alcohol media

The extraction of protactinium with organic solvents has been investigated in the presence of water-miscible alcohols and acetone. These additives were found to increase considerably the extraction of protactinium in the cases of trilaurylamine, tributyl phosphate and isobutyl methyl ketone. The influence was less in the case of thenoyltrifluoroacetone. In mixtures of an acid with various alcohols, the influence depended on the alcohol concentration, the acidity and on the chain lengths and dielectric constants of the alcohol introduced into the extraction system.     

Extraction of zinc with tri(iso-octyl)amine in methyl isobutyl ketone and colorimetric determination with zincon in the organic phase

A study was made of the extraction of zinc from hydrochloric acid solutions with solutions of methyldioctylamine and tri(iso-octyl)amine in methyl isobutyl ketone. Quantitative extraction was accomplished from 2 N hydrochloric acid with 5% (w/v) tri(iso-octyl)amine-methyl isobutyl ketone. A procedure was developed for the colorimetric determination of zinc in the organic phase after extraction using 2-carboxy-2'-hydroxy-5'-sulfoformazylbenzene (Zincon).