Prolonged Stirring Research Articles

Regiospecific oxidation of unsaturated fatty esters with palladium(II) chloride/ p-benzoquinone: a sonochemical approach

Oxidation of unsaturated fatty esters to the corresponding oxo derivatives was accomplished in moderate to high yields when the substrates were treated with palladium(II) chloride and p-benzoquinone in aqueous tetrahydrofuran (THF/H 2O, 4:1 v/v) under ultrasound (20 kHz). Methyl 10-undecenoate furnished methyl 10-oxoundecanoate in 92% yield. Methyl oleate and trans-2-hexadecenoate furnished methyl 9(10)-oxoundecanoate (65%) and methyl 3-oxohexadecanoate (41%), respectively. Unsaturated fatty esters with a terminal double bond were more readily oxidized than those containing an internal double bond. Methyl trans-3,12-tridecadienoate gave only methyl 12-oxo- trans-3-tridecenoate (86%), while a cyclopentanoic fatty ester (methyl chaulmoograte) furnished a mixture of positional oxo-isomers: viz. methyl l-oxocyclopentane-2-tridecanoate and 1-oxocyclopentane-3-tridecanoate (51.5% total). Oxidation of methyl 12-hydroxy-, 12-azido-, 12-chloro- and 12-oxo- cis-9-octadecenoate furnished the corresponding 9-oxo-derivatives only. Methyl iso-ricinoleate (methyl 9-hydroxy- cis-octadecenoate) gave exclusively methyl 9-hydroxy-12-oxostearate. Without ultrasonication the same oxidation reactions at room temperature furnished low yields (< 30%) of the corresponding oxo derivatives after prolonged stirring at room temperature. Aqueous THF is a superior solvent system than the commonly used aqueous N, N-dimethylformamide (DMF).

Monodentate sigma-N and Bidentate sigma-N,sigma-N' Coordination of 1,1-Bis((N-p-tolylimino)diphenylphosphoranyl)ethane, CHCH(3)(PPh(2)=NC(6)H(4)-4-CH(3))(2), to Platinum(II).

The new ligand, 1,1-bis((N-p-tolylimino)diphenylphosphoranyl)ethane (1,1-BIPE), 1, has been synthesized by means of a Staudinger reaction of 1,1-bis(diphenylphosphino)ethane (1,1-dppe) with 2 equiv of p-tolylazide. Bridge-splitting reactions of Pt(2)Cl(4)(PR(3))(2) with 1 readily afforded sigma-N monodentate complexes, [PtCl(2)(PR(3)){1,1-BIPE-sigmaN}] (2a, PR(3) = PEt(3); 2b, PR(3) = PMe(2)Ph). Conversion of 2 into the six-membered platinacycle [PtCl(PR(3)){1,1-BIPE-sigmaN,sigmaN'}](+)[X](-) (3) (X = Cl, PtCl(3)(PR(3)), BF(4)) took place after prolonged stirring, its reaction rate being strongly dependent on the type of phosphine (>5 days for 2ain the presence of NaBF(4), 1 h for 2b) and the metal-to-ligand ratio. The compounds 1, 2, and 3 have been fully characterized by (1)H, (31)P{(1)H}, and (13)C{(1)H} NMR and IR spectroscopy, elemental analysis, or FAB mass spectroscopy. The molecular structures of CHCH(3)(PPh(2)=NC(6)H(4)-4-CH(3))(2) (1) and [PtCl(PMe(2)Ph){(N(pTol)=PPh(2))(2)CHCH(3)}](+)[Cl](-) (3b) have been determined by X-ray crystallography. Crystal data for 1: space group P2(1)/c with a = 8.9591(5) Å, b = 19.1961(12) Å, c = 21.9740(9) Å, beta = 105.069(4) degrees, V = 3649.1(3) Å(3), and Z = 4. The structure refinement converged to R = 0.080 and R(w) = 0.109. Crystal data for 3b: monoclinic, space group P2(1)/c with a = 12.4021(7) Å, b = 16.9705(11) Å, c = 23.760(2) Å, beta = 109.544(5) degrees, V = 4712.7(5) Å(3), and Z = 4. The structure refinement converged to R1 = 0.057, wR2 = 0.122. Variable temperature NMR spectroscopy has revealed that complexes 3 exclusively adopt a twisted boat conformation with the methyl group in equatorial position at low temperature, in agreement with the solid state structure of 3b as determined by X-ray crystallography. Boat-to-boat inversion is assumed to take place at temperatures above 293 K. Furthermore, for 3, hindered rotation of one of the p-tolyl substituents on nitrogen has been established at low temperatures.

Reactions of the hexanuclear mixed-metal cluster [Ru5RhC(CO)14(η5-C5Me5)] and the synthesis, characterisation and structural analysis of the pentanuclear derivative [Ru4RhC(CO)12(η5-C5Me5)

Treatment of the hexanuclear cluster [Ru5RhC(CO)14(η5-C5Me5)]1 with 80 atmospheres of CO under 80 °C resulted in a series of decapping reactions yielding the complexes, [Ru3(CO)12], [Ru5C(CO)15] and a new green compound [Ru4RhC(CO)12(η5-C5Me5)]2. Cluster 2 crystallises in the monoclinic space group P21/n with a= 19.180(3), b= 13.940(3) and c= 10.728(2)A, β= 97.157(2)°. The five metal atoms adopt a square-based pyramidal metal framework [Ru–Ru 2.776(1)–2.873(1), Ru–Rh 2.798(1)–2.881 (1)A]. The octahedral cluster [Ru5RhC(CO)14(η5-C5Me5)]1 reacted at room temperature with a methanolic base to yield the methoxide adduct [Ru5RhC(CO)13(CO2Me)(η5-C5Me5)]–3 which on acidification immediately regenerated the parent compound. On prolonged stirring, cluster 1 reacted irreversibly with the methanolic base to form the salt [N(PPh3)2]2[Ru5RhC(CO)13(η5-C5Me5)]4.

Synthesis and electrochemistry of organometallic ethanethiolato bridged complexes of ruthenium(IV)

Reaction of the ruthenium(IV) chloro-bridged dimer [{Ru(η 3 : η 3-C 10H 16)Cl(μ-Cl)} 2], 1, with ethanethiol (EtSH) in CH 2Cl 2 gives the bridged-cleaved adduct [Ru(η 3 : η 3-C 10H 16)Cl 2(SHEt)], 2. Stirring of two molar equivalents of 2 in methanol with one equivalent of 1 gives the binuclear, mixed chloro/thiolato bridged compound [{Ru(η 3 : η 3-C 10H 16)Cl} 2(μ-SEt)], 3. The related doubly thiolato bridged complex [{Ru(η 3 : η 3-C 10H 10)Cl(μ-SEt)} 2], 4, is formed by treatment of 1 with an excess of EtSH, or by prolonged stirring of 2 alone in methanol. Compounds 2–4 have been studied by cyclic voitammetry. Compound 2 undergoes only irreversible oxidation, whereas in the case of both 3 and 4 the observation of significant return waves is consistent with a greater stability of the primary redox products.

Predictive Stress Tests in the Scale-Up of Capsule Formulations

AbstractIn early development, supplies of bulk active are limited and capsule formulations are developed on a small scale. However they should be suitable for scale-up. In this report, the Turbula T2C is shown to mimic the prolonged stirring and stressing of powder blends in the large hopper of a dosator type machine, e.g. Zanasi LZ64. The degree of mixing affects the lubricity and wettability of capsule blends containing magnesium stearate and stressing powder blends in a Turbula T2C highlights changes in blend properties which occur on scale-up. Measuring tapped bulk density, wettability and disintegration of stressed blends identifies robust formulations which are unaffected by long “lubrication” times and scale. Changes in blend properties are influenced more by shearing energy than the extent of mixing

Soluble Fractions of Pasteurella multocida: Their Protective Qualities against Fowl Cholera in Turkeys

Soluble fractions of Pasteurella multocida strain P1059 were extracted from a single source by four methods, and their immunogenicity was evaluated by challenge exposure in turkeys. The fractions were extracted by 1) heating in 2.5% NaCl, 2) 0.5M potassium thiocyanate, 3) 1.0M sodium salicylate, and 4) prolonged stirring in formalin solution followed by pelleting (LPS-protein antigen). Eighty percent to 90% of infected turkeys were protected in two trials by vaccination with the saline extract or LPS-protein antigen, whereas less consistent protection was associated with the other two preparations. Endotoxin content was the highest in LPS-protein antigen, followed by KSCN, Na salicylate, and saline extract in that order. The four fractions contained at least one common antigen, which had previously been shown to be a surface-protective antigen.

Tetraphenylcyclobutadienecycloalkenenickel(0) Complexes

Nickel(0) complexes having only one tetraphenylcyclobutadiene ligand (Ph4C4) and one cycloalkene ligand (L) are accessible with surprising ease, e.g. by prolonged stirring of the reagents given below in either at −50°C. (1a) and (1b), green crystals, only decompose at 220 and 260°C, respectively. [(1a), L = 1,5‐cyclooctadiene; (1b), L = cyclooctatetraene.] equation image

Masking of Bacillus megaterium KM membrane reduced nicotinamide adenine dinucleotide oxidase and solubilization studies.

Solubilization of a reduced nicotinamide adenine dinucleotide (NADH)-2,6 dichlorophenol indophenol (DCIP) oxidoreductase associated with the membrane NADH oxidase system of Bacillus megaterium KM was effected by treatment with 0.2% sodium deoxycholate, 8 m urea, or buffer (pH 9.0) in the presence of ethyl-enediaminetetraacetate. These treatments inactivated membrane NADH oxidase. It was found that membrane NADH oxidase and NADH-DCIP oxidoreductase were masked in membranes. Several procedures, including brief sonic oscillation, treatment with 0.05% deoxycholate, prolonged stirring at 4 C with 10% glycerol, and washing in the absence of Mg(2+), unmasked the oxidase and oxidoreductase activities. It was necessary to study the masking and unmasking of these activities to quantitate adequately the effects of solubilization procedures. Further information on the localization of oxidase and oxidoreductase in subcellular fractions and the effects of electron transport inhibitors on NADH oxidation was also obtained.

Improved Preparation of Polyvinyl Alcohol-HgCl2Fixative Used for Fecal Smears

Rather than dissolve polyvinyl alcohol (PVA) powder in a modified Schaudinn's fixative (containing glycerol) by prolonged heating and stirring, it was found better to coat the particles of PVA with glycerol first. PVA powder (Delkote brand), 5 gm, mixed with 1.5 ml of glycerol and added to 62.5 ml of distilled water, is allowed to soak 3–16 hr in a stoppered flask, then heated to 70–75 C in a water bath (with swirling) for about 10 min or until solution is complete. A separate solution of the other ingredients: 95% ethanol, 31 ml; HgCl2 4.5 gm; and glacial acetic acid, 5 ml, is then added to the heated PVA solution, and swirled in the stoppered flask until the mixture becomes clear. This fixative is easy to make, produces little or no sediment, does not thicken with age, and has a long shelf life. It is strongly adhesive and fixes protozoa as well or better than that made by the older method or purchased ready made.

On a type of photoelastic mottle in an epoxy resin

Prolonged stirring of Araldite 6020 and phthalic anhydride before casting has resulted in considerable reduction of mottle and minor improvements in clarity and figure of merit. Some care is required to avoid premature gelation and the inclusion of air bubbles and foreign particles.

The age-thickening of sweetened condensed milk: I. Rheological properties

SummaryThe viscosity and flow properties of fresh and age-thickened separated sweetened condensed milk have been investigated using a rotating cylinder viscometer. The rheological properties, and the changes therein brought about by stirring, were studied by means of flow curves obtained by plotting stress against the corresponding rate of shear. Condensed milk during age-thickening is shown to develop thixotropic properties, with a high initial viscosity or ‘gel strength’ which, however, is easily reduced by stirring. On prolonged stirring the viscosity reaches a minimum (the ‘permanent’ viscosity), which becomes progressively higher as the age-thickening process continues. On storage subsequent to stirring there is only an insignificant recovery of the lost viscosity at room temperature, but a substantial recovery at higher temperature.Sweetened condensed whey shows no age-thickening, and the casein-free supernatant liquids obtained by centrifuging dilutions of both fresh and age-thickened condensed milk have the same nitrogen contents and the same viscosities. This is interpreted to mean that the whey proteins play no significant part, directly or in association with casein, in the age-thickening process. Also the sedimentation rate of the casein during centrifuging is greater with age-thickened than with fresh condensed milk, which indicates an increase in casein particle size during agethickening.The following working hypothesis is suggested to account for this behaviour. During age-thickening a slow irreversible change occurs in the size or shape of the casein micelles, probably by aggregation, which produces the rise in ‘permanent’ viscosity. These micelles orient themselves in such a way as to form a loose network enclosing some of the dispersion medium, thereby producing the large increase in the initial viscosity. On stirring, this network is broken down, and although it can reform in time at high temperatures, such recovery is greatly retarded at room temperature by the high viscosity of the aqueous phase containing the soluble constituents of the condensed milk.