Dehydration incomplete

Carbon monoxide is formed by the incomplete combustion of carbon. It is prepared in the laboratory by dropping methanoic (formic) acid into warm concentrated sulphuric acid the latter dehydrates the methanoic acid ... 

Carbon monoxide is produced by incomplete combustion of carbon and its compounds. In the laboratory it can be prepared by careful dehydration of formic or oxalic acid with sulphuric acid ... 

Polymetatelluric acid (H2TeO4). ]0 is a white, amorphous hygroscopic powder formed by incomplete dehydration of HgTeOg in air at 160°. Alternatively, in aqueous solution... 

The relatively low percentage of ring substitution can be attributed to several side reactions 1,4-addition of Li to 2-cyclopentenone, incomplete dehydration of 4 as evidenced by the presence of a small hydroxyl absorption (3425 cm ) in the IR spectrum of 5, and reduction of the polymer-bound cyclopentadiene in its reaction with Co2(C0)8 (26,27,32). 

Although the specific role of each type of center (acid or base) in each process (dehydration-dehydrogenation) is still only incompletely elucidated, many authors have correlated the initial rates of dehydration and dehydrogenation with the acidity and basicity, respectively, of the solid. Thus, the number of basic sites has been correlated with the rate constants for dehydrogenation or with the ratio of the rate constants for dehydrogenation and dehydration (74,80,89,90,94). 

Various preparative methods are adopted at nonstoichiometric formulations, incomplete dehydration or using oxide additives to obtain boron phosphate of varying purity for its catalytic applications. The compound also forms hydrates (tri- tetra-, penta-, and hexahydrates) which readily decompose in water to phosphoric acid and boric acid. 

Tetrahydrothiazin-3-ones are lactams that have been reduced to tetrahydrothiazines with borane <1980JHC449>, sodium borohydride <1992JOC4215>, or LAH <1987H(26)1503>, without cleavage of carbon-sulfur bond. In one case, incomplete reduction occured with LAH the intermediate lactol was dehydrated to give a dihydrothiazine as main product <1989JPS937>. 

Excess reductant and alkali halide are evaporated from the reaction mixture leaving, however, non volatile impurities in the metal, including oxygen from incompletely dehydrated starting halides. 

Still with the prebiotic scenario, the conditions developed by Limtrakul et al. (1985) are interesting as a consequence of evaporation, high local concentrations may have arisen, and under such conditions the incompletely hydrated metal ions may activate a dehydration leading to peptide condensation. From this, the technique of the salt induced peptide condensation (SIPC) has been developed (Oie et al, 1983 Suwannachst and Rode, 1999 Rode et al, 1999). 

It has been shown that only those alcohols that form detectable surface alco-holate species on alumina undergo bimolecular dehydration with ether and water as reaction products (340). Thus, ether formation is the dominant reaction direction of methanol and ethanol at low temperatures, and the tendency toward ether formation is reduced as the chain length increases and chain branching occurs (28, 340). The same trends are observed for the stability and surface concentrations of the surface alcoholate species (27, 28, 47, 340). Alcoholate formation is due to a dissociative chemisorption step of the alcohol that occurs on A1—O pair sites (47, 340, 354-358). One is, thus, led to the conclusion that incompletely coordinated Al3+ ions and O2- ions are both important sites in the ether formation from alcohols and that their participation should be detectable by specific poisoning. 

The following description is taken from Marshall (Ref 1) As the cords, strips, tubes, etc of a single-base proplnt emerge from the die-press, they are usually wound on frames provided with springs which allow the cords, etc to contract as the solvent evaporates. In case of cords, etc of large diam, they are nailed to the frames. The frames are then placed in a "stove (similar to that briefly described under Dehydration and Drying of Nitrocelluloses) where the air, heated not above 40°, is circulated from top to bottom until the bulk of the solvent is removed. The spent air is passed thru an apparatus for solvent recovery and the incompletely dried proplnt cords, etc are removed from the stove. 

During this heating any carbinol present is dehydrated. Low and erratic yields usually indicate incomplete dehydration. 

Examples of systematic error are a calibration error in the instrument, failure to establish properly a zero reading of the instrument scale, improper graduation or ahgmnent of an instrumental scale, uncompensated instrumental drift, leakage of material (e.g., of gas in a pressure or vacuum system) or of electricity (in an electrical circuit), and incomplete fulfillment of necessary experimental conditions (e.g., incomplete reaction in a calorimeter, incomplete dehydration of a sample prior to weighing). An example of another kind is faulty theoretical treatment of the results of the measurements to obtain the desired result, perhaps through a faulty approximation in the phenomenological theory involved. 

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