Colloid reaction

To a pressure bottle are added 43 ml of 10% chloroplatinic acid, 0.5 gm of gumarabic, and 10 ml of water, 50 ml of methyl alcohol, 1.0 ml of hydrochloric acid, and 10.0 gm (0.052 mole) of fenchylsemicarbazone. The mixture is shaken at over 2 atm hydrogen pressure until the theoretical amount of hydrogen is absorbed. The colloidal reaction mixture is added to acetone and the solution is concentrated under reduced pressure. The residue is precipitated with ammonium hydroxide. Recrystallization of the product from ethyl acetate affords 10.1 gm (100%), m.p. 181°C. 

The extinction coefficient of the complex formed in Ti02 colloid reaction mixtures at 430 nm has the value of 5.2xl03 dm3 mol-1 cm-1... 

Factors Affecting PEO Agglomeration. By using Equation 3, it is easily possible within a relatively short time to study the effects of the many factors which usually play a part in polymer-colloid reactions and which have to be considered in PEO agglomeration, too. These factors are tabulated in Table I according to reactants and reaction conditions. 

Henglein, A., Kumar, A., Janata, E., and WeUer, H. 1986. Photochemistry and radiation chemistry of semiconductor colloids Reaction of the solvated with CdS and non hnear optical effects. Chem. Phys. Lett. 132 133-136. 

A colloidal reaction product appears to form at the volume ratio corresponding to the conductance peaks in the case of the aminoglycoside-heparin mixture. The suspensoid readily redissolves on agitation the turbid reaction mixture clarifies on shaking. 

Mulvaney, P. Zeta potential and colloid reaction kinetics, in Nanoparticles and NanostructuredFilms (Ed. J. H. Fendler), 1998, Wiley-VCH, Weinheim (Germany). 

A significant improvement in the TL intensity of Y-compound hosts was obtained by Erdei et al. (19%). They present three-dimensional plots of the TL spectra of Eu-and Ce-doped YVO4 and YVo,4Po,604 phosphors. The phosphors were prepared by a hydrolyzed colloid reaction at about 80"C and then fired at high temperatures. The defect structure was found to depend on the parameters of the hydrolyzed colloid reaction. The phosphors showed TL peaks at about 85 C and 135"C. The TL intensities of these two peaks were highest for the mixed Yo.960o.4Po.604-Eu (0.04) 6800 and 4600 compared to 100 and 80 for the 80"C and 130"C peaks of the 04 Eu phosphor, respectively. The authors relate this improvement to an increased defect concentration in the anion sublattice by the introduction of the PO. ... 

Cu-cores supported on Vulcan XC72 can be modified in a so-called colloid reaction. Cu-acetylacetonate is reduced, leading to finely dispersed metal cores on the carbon support. In a subsequent reduction step, platinum shells are deposited... 

Biltz found further that where acid and basic dyestuffs had opposite charges and were mutually precipitated, the formation of an insoluble chemical combination could be assumed. This corresponds to what is known of acid and basic dyestuffs in the state of crystalloids namely that they unite, and when the combination is insoluble a precipitate is of course formed. Doubtless such reactions occur in the case of many dyestuffs. The more colloidal the character of these dyestuffs the more nearly will the laws of colloidal reaction obtain. Moreover Biltz has pointed out that with colloids of the nature of gold such chemical reactions are not possible. Nevertheless colloidal gold is precipitated by positively charged dyestuffs. The cause is doubtless the neutralization of the charge on the particles. For further particulars attention is called to Chapter XI. 

The heat of colloidal reactions is generally very small. That it is appreciable during distension and dissolution of gelatin has been shown by AiV iedemann and Luedeking. l The results for irreversible colloids... 

In the following paragraphs a few specific examples will be given to show how peptisation and a number of other colloidal reactions may be explained in a simple manner on the basis of adsorption of ions. 

Pigments that have very small particle size, such as carbon black, iron blue, and certain organic pigments, may produce a physical or colloidal reaction in paint. The reaction results in an increase in consistency, which may become so great that an irreversible sol-gel transformation occurs and the paint becomes similar in texture to liver of human body. The phenomenon is referred to as livering, but the mechanism is not well understood. Apparently, pigment-vehi-... 

Magnetic semiconducting materials have also been explored cobalt phosphide (C02P) nanowires have been synthesised by a one-pot colloidal reaction of cobalt oleate in TOP at 290 or 320 °C [Fig. 14(a),(b)]. Initially, cobalt (II) carbonate reaeted with oleic acid at 80 °C in TOP to form cobalt (II) oleate which was further heated up to obtain cobalt phosphide nanostructures. When OAm was added to the reaction pot at 290 or 320 °C, C02P or CoP nanorods were formed respectively [Fig. 14(c),(d)]. The erystallite size of the nanowires (5.6 and 6.6 nm) and nanorods (8.7 and 14 nm) increased with reaction temperature according to XRD analysis. Ternary cobalt iron phosphide nanostructures were synthesised by the reaction of iron (III) oleate and cobalt (II) oleate with TOP in the presence of OAm. Coi.sFeo.sP nanorice was obtained at 290 °C, whereas C01.7Feo.3P parallel/ perpendicular split nanostructures was formed at 320 °C [Fig. 14(e),(f)]. 

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