Solid state suspensions

If diazomethane is added slowly to an etheral suspension of benzo-l,2,4-triazin-3-one, the 0-methyl derivative (cf. 161) is obtained in good yield, but, if the solid benzotriazinone is added to an etheral solution of diazomethane, approximately 50% of the A -methyl derivative (or, according to a later report, 70% of a mixture of two isomeric iV-methyl derivatives) is formed. These facts have been interpreted to indicate that the benzotriazinone exists as such in the solid state, i.e., as 162, and partially tautomerizes to 161 in solution. Similar results have been reported and similar conclusions drawn for the related 1-oxide 162a. ... 

When the polymer was prepared by the suspension polymerization technique, the product was crosslinked beads of unusually uniform size (see Fig. 16 for SEM picture of the beads) with hydrophobic surface characteristics. This shows that cardanyl acrylate/methacry-late can be used as comonomers-cum-cross-linking agents in vinyl polymerizations. This further gives rise to more opportunities to prepare polymer supports for synthesis particularly for experiments in solid-state peptide synthesis. Polymer supports based on activated acrylates have recently been reported to be useful in supported organic reactions, metal ion separation, etc. [198,199]. Copolymers are expected to give better performance and, hence, coplymers of CA and CM A with methyl methacrylate (MMA), styrene (St), and acrylonitrile (AN) were prepared and characterized [196,197]. 

Thermal solid-state reactions were carried out by keeping a mixture of powdered reactant and reagent at room temperature or elevated temperature, or by mixing with pestle and mortar. In some cases, the solid-state reactions proceed much more efficiently in a water suspension medium or in the presence of a small amount of solvent. Sometimes, a mixture of solid reactant and reagent turns to liquid as the reaction proceeds. All these reactions are called solid-state reactions in this chapter. Solid-state reactions were found to be useful in the study of reaction mechanisms, since it is easy to monitor the reaction by continuous measurement of IR spectra. 

The stability of suspensions, emulsions, creams, and ointments is dealt with in other chapters. The unique characteristics of solid-state decomposition processes have been described in reviews by D. C. Monkhouse [79,80] and in the monograph on drug stability by J. T. Carstensen [81]. Baitalow et al. have applied an unconventional approach to the kinetic analysis of solid-state reactions [82], The recently published monograph on solid-state chemistry of drugs also treats this topic in great detail [83],... 

Heating the metal carboxylate in the solid state, in solution, or as a suspension... 

Fig. 7 Comparison of the solid-state 31P-NMR spectra from erythrocyte ghosts (left column) and of DMPC model membranes (right column). Samples are prepared as a non-oriented suspension in excess water (a, d), and as macroscopically oriented membranes on glass slides that are aligned either parallel (b, e) or perpendicular (c, f) to the static magnetic field...

Sulfathiazole has been found to crystallize in three distinct polymorphic forms, all of which are kinetically stable in the solid state but two of which are unstable in contact with water [130]. As evident in Fig. 20, the initial intrinsic dissolution rates are different, but as forms I and II convert into form III, the dissolved concentrations converge. Only the dissolution rate of form III was constant during the studies, indicating it to be the thermodynamically stable form at room temperature. Aqueous suspensions of forms I or II were all found to convert into form III over time, supporting the finding of the dissolution studies. Interestingly, around the melting points of the three polymorphs, form I exhibited... 

Freeze drying or lyophilization is a drying process, in which the solvent and/or the medium of suspension is crystallized at low temperatures and thereafter sublimated from the solid state directly into the vapor phase. 

Stability and decomposition kinetics of aspirin both as a solid and in solution continue to be studied. The topochemical decomposition pattern of aspirin tablets has been explored.175 The degradation of aspirin in the presence of sodium carbonate and high humidity was studied by x-ray diffraction.176 The activation energy of decomposition by water vapor in the solid state was found to be 30 kcal/mol.177 The effect of common tablet excipients on aspirin in aqueous suspension was also studied.178... 

Solids retention time (SRT), 25 900 Solids separation, in solid-liquid separation, 11 342, 344 Solids suspension(s), 7 272t, 16 692-696 degrees of, 16 693 occurrences of, 7 273t Solid-state hydrogen, 13 850 Solid-state crossed Cannizzaro reactionp, 16 574... 

Salts of O-alkyldithiocarbonatcs ( xanthates ) are hazardous as dusts, forming explosive suspensions in air. The lower-alkyl salts are claimed to be explosive in the solid state when dry [1]. Explosions reported when drying hydrated xanthate salts are probably the consequence of release of carbon disulphide to form an inflammable atmosphere of very low autoignition temperature in the oven [2], Xanthate esters are thermally unstable by a variety of eliminations and rearrangements, all distinctly exothermic and many evolving extremely flammable gases and vapours. Free xanthic acids, which may be isolated on acidification, decompose autocatalytically and perhaps explosively [3],... 

Ansarian, H.R., Derakhshan, M., Rahman, M.M., Saknrai, T., Takafnji, M., Tanigu-chi, I., and Ihara, H., Evalnation of microstructuralfeatnres of a new polymeric organic stationary-phase grafted on silica surface a paradigm of characterization of HPLC-stationary phases by a combination of suspension-state H-1 NMR and solid-state C-13-CP/MAS-NMR, Anal. Chim. Acta, 547,179, 2005. 

The solvent-mediated transformation of o -L-glutamic acid to the S-form was quantitatively monitored over time at a series of temperatures [248]. The calibration model was built using dry physical mixtures of the forms, but still successfully predicted composition in suspension samples. Cornel et al. monitored the solute concentration and the solvent-mediated solid-state transformation of L-glutamic acid simultaneously [249]. However, the authors note that multivariate analysis was required to achieve this. Additionally, they caution that it was necessary to experimentally evaluate the effect of solid composition, suspension density, solute concentration, particle size and distribution, particle shape, and temperature on the Raman spectra during calibration in order to have confidence in the quantitative results. This can be a substantial experi-... 

Crystalline macrocyclic polyether complexes may be prepared by several routes,5,381 depending upon the solubilities of the precursors and the products. The polyester and the salt may be dissolved in a small amount of solvent and warmed together the complex can crystallize either on cooling or after evaporation of some of the solvent. It is also possible to warm a suspension of the ligand and the salt to effect solubilization and subsequent crystallization. The reaction can also be carried out by mixing the components in the solid state and heating to melting. 

The indium(II) halides, whose solid state structures are In+[InX4] for X = Br and I (see Section 25.2.2.5), have served as starting points for the preparation of [IntcrownJJpnX X = Cl, Br, I), [In(crown)][AlCl4] and [In(cyclam)][InX4](X = Br, I crown = dibenzo-18-crown-6 cyclam = 1,4,8,11-tetraazacyclotetradecane).24 The characteristic vibrational spectra of the InXj anions were important in establishing the solid state structure of these salts of indium(I) cationic complexes. These macrocydic ligands do not react with suspensions of InX (cf. thallium below). 

Arsenious oxide in the solid state is not affected by oxygen under ordinary conditions,4 but if subjected at high temperature to oxygen under pressure oxidation to the pentoxide results. Thus, if heated at 400° to 480° C. with oxygen at pressures of 130 to 180 atm., oxidation occurs, but is incomplete the amount oxidised increases with the temperature.3 According to Razuvaev and Malinovskil,6 at 200° to 300° C. the optimum pressure for oxidation by air is 60 to 80 atm., and under these conditions the reaction is complete in about 20 minutes finely divided iron has a wreak and copper a strong catalytic effect. In the presence of potassium iodide or activated carbon, a suspension of the oxide in water is oxidised by air or oxygen at 130° to 140° C. and 4 to 5 atm. pressure.7 The usually accepted reaction is... 

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