Solution condensation

Preparing a Volatile Sample Gas chromatography can be used to separate analytes in complex matrices. Not every sample that can potentially be analyzed by GG, however, can be injected directly into the instrument. To move through the column, the sample s constituents must be volatile. Solutes of low volatility may be retained by the column and continue to elute during the analysis of subsequent samples. Nonvolatile solutes condense on the column, degrading the column s performance. 

Irregular grooving can occur, especially on copper alloys after acid cleaning. Tubes can be only partially filled with cleaning solution. Condensation and running of the fluid down the tube interior cuts tortuous channels (Fig. 7.9). 

The phenyl ether linkage of butoxy substituted 44 was cleaved with boron tribromide to give a hexaphenol derivative (45) in 60% yield (Scheme 14). The hexaphenol derivative was found to be remarkably soluble in most polar organic solvents, such as ethanol, DMF, DMSO, and dioxane, as well as in aqueous base solution. Condensation with octanoic acid in the presence of DCC and catalytic H+ afforded the inverse ester (46) in high yield. 

One example is silicate cement where orthosilicic acid, chemically generated in solution, condenses to form a silicic acid gel. Another is refractory cement where a cementitious product is formed by the heat treatment of an acid orthophosphate, a process which again involves condensation to form a polyphosphate. 

Orthosilicic acid at concentrations above 100 ppm in solution condenses to a dimer. At higher concentrations cyclic and polymeric species are formed (Her, 1979 Andersson, Dent Glasser Smith, 1982). These processes are ones where silanol groups condense to form siloxane linkages ... 

Insensitive to impact, it decomposes, sometimes explosively, above its m.p. [1], particularly if heated rapidly [2], Although used in aqueous solutions as a preservative in pharmaceutical preparations, application of freeze-drying techniques to such solutions has led to problems arising from volatilisation of traces of hydrazoic acid from non-neutral solutions, condensation in metal lines, traps or filters, and formation of heavy metal azides in contact with lead, copper or zinc components in the drying plant [3,4],... 

Preparation of poly(m-phenylene)iso/terephthalate (80/20). The polymers were prepared by solution condensation of the acid chlorides with resorcinol in methylene chloride solution using triethyl amine as the acid acceptor as described by Korshak (10). 

Solution condensations are also equilibrium processes, with the reaction often driven by removal of the by-product through distillation, salt formation, or precipitation. Many solution condensations are carried out near room temperature. Solvent entrapment is a problem, but since a reaction may occur under considerably reduced temperatures, compared to the melt process, thermally induced side reactions are minimized. Side reactions with the... 

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. 

These porous structures may hinder the transport of solutes away from the membrane downstream surface, causing a local increase of the solute partial pressure and hence a decrease of the driving force (19.1). Eventually, solute condensation may occur if the solutes local partial pressure surmounts its saturation vapour pressure. This problem becomes particularly relevant when dealing with high-boiling aroma compounds [14] and when pressure drop in the downstream circuit increases owing to poor module design. 

Shirai et al. [71] also synthesized a novel class of polyimides containing M(II) phthalocyanine rings by solution condensation in iV-Me-2-pyrrolidone of M(II) [2,9, or 10,2,16 or 17-bis(3,4-dicarboxy benzoyl)] phthalocyanine dianhydride with 2,6-diaminopyridine followed by thermal imidation [71] (Fig. 23). 

The adsorbents were heated 3 hours in air at 630° before the spectral measurements in order to eliminate any organic impurities present, and afterwards they were degassed at 350°C under high vacuum for about 1 hour. The solvent vapour (CC14) and subsequently a measured amount of the degassed compound studied were condensed on to it in vacuum by cooling down to — 180°C. After this the solution condensed on it was brought to room temperature to achieve a uniform distribution of the solute. The concentrations of the solutions varied from 1 JO to 1 39 volume ratio. 

We have been interested in developing new routes to mesostructured metal sulfides. Our approach capitalizes on well-established solution condensation reactions that can transform discrete, soluble metal thiolate species into solid-state metal sulfide compounds. Here we wish to describe the use of (NH4)2WS4 as a precursor material in the synthesis of three mesostructured tungsten suldifes with the inorganic walls that consist of continuous WS3 chains and WS2. 

If a drop of piperidine is added to a pasty mixture of TNT and benzaldehyde, the heat of the reaction is sufficient to cause the material to take fire. The same substances in alcohol or benzene solution condense smoothly in the presence of piperidine to form trinitrostilbene.34... 

Polyamideimide Resin (PAI). Amoco introduced the first commercial polyamideimide (PAI) resin, Todon, in the eady 1970s (107,108). It is produced by the solution condensation of trimellitic trichloride with methylenedianiline (109) ... 

Polypyrazoles of the type 62 have been prepared.65 These polymers are formed from the low-temperature solution condensation of 1,1 -bis(diketo)ferrocenes with aromatic or pseudoaromatic dihydrazines to give polyhydrazones which are transformed thermally to the polypyrazoles. Polybenzimadazole (63) has been prepared68 from l,l -ferrocenedicarboxylic acid and 3,3 -diaminobenzidine. 

Recently, Johnson et al. (2) reported the synthesis of several aromatic polyethers by nucleophilic aromatic substitution reactions. These solution condensations take place between the diphenoxide salt of a bisphenol and an aromatic dihalide ... 

The novolac used in this study was prepared by the base catalyzed solution condensation of m-cresol with formaldehyde (Mn = 1800,... 

Dehumidification is the removal of a solute liquid vapor from a gas phase by the solute condensing into its liquid phase. The removal of water vapor in air by condensation on a cold surface is dehumidification. The reverse of dehumidification is humidification. In this unit operation, the flow of the solute is from the liquid phase evaporating into the gas phase. The end result of this movement is saturation of the gas. For example, during heavy rains, the atmosphere may become saturated with water vapor, the degree of this saturation being measured by the relative humidity. Liquid extraction is the removal of a solute component from a liquid mixture called the raffinate using a liquid solvent. In this operation, the solvent preferentially dissolves the solute molecule to be extracted. 

Dehumidification—The removal of a solute liquid vapor from a gas phase by the solute condensing into its liquid phase. 

In order to get more structurally pure polyPc a new way may start from multifunctional low molecular Pc. Co(II), Ni(II) and Cu(II) containing bis(dicarboxybenzoyl) Pc diimides were converted with various aromatic diamines in N-methylpyrrolidone to soluble polyamides which react to insoluble polyimides (9S) by heating to 473 K ). Melt and solution condensation of (12 b) and 3,3 -diaminobenzidine led to unsoluble polymers (99) with Pc-rings linked by benzimidazole units ). 

Reaction of borane-THF complex with mono(2,6-diisopropyl)benzoyltartaric acid in dry propionitrile at 0 °C affords the catalyst solution. Condensation of achiral aldehydes with allylsilanes is promoted by this catalyst, 2, (20 mol %) at -78 °C to produce homoallylic alcohols with enantio- and diastereoselectivity (Eq. 66). 

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