Dehydration general

If left untreated, bacfllary dysentery usually lasts about 1 week (range 1-30 days). Complications are unusual but may include severe dehydration, generalized seizures, septicemia, toxic megacolon, perforated colon, arthritis, protein-losing enteropathy, and HUS. Mortality is rare, but it may be more likely with S. dysenteriae type I. Fess than 3% of persons who are infected with S. flexneri will later develop Reiter s syndrome, characterized by pains in the joints, irritation of the eyes, and painful urination. This can lead to chronic arthritis. ... 

Most alcohols undergo elimination of water in ionizing solution in the presence of either Lewis (e.g., Scheme 8.27) and/or Brpnsted acid catalysts. For alkyl alcohols, the rate of dehydration generally follows carbocation stability, that is, as in the El reactions of alkyl hahdes (Chapter 7) tertiary > secondary > primary. 

In the acid-catalyzed condensation of acetone, the enol is the intermediate, and it adds to the very strong Lewis acid, the protonated carbonyl group, to give initially the same product as the base-catalyzed reaction, diacetone alcohol (Fig. 19.73). Dehydration generally follows to give the a,P-unsaturated ketone, 4-methyl-3-penten-2-one (mesityl oxide). 

Fig. 19.74). In add, dehydration generally occurs and formation of the a,P-unsaturated ketone pulls the equilibrium to the right. 

The removal of water from a material. In nutrition, dehydration generally means one or both of the following ... 

Facilities for the treatment and compression of gas have already been described in earlier sections. However, there are a number of differences in the specifications for injected gas that differ from those of export gas. Generally there are no technical reasons for specifications on hydrocarbon dew point control (injected gas will get hotter not cooler) although it may be attractive to remove heavy hydrocarbons for economic reasons. Basic liquid separation will normally be performed, and due to the high pressures involved it will nearly always be necessary to dehydrate the gas to avoid water drop out. 

Amylene is a general name for the ethylenic hydrocarbons of the molecular formula CjHio. Two of these hydrocarbons are the main products of the dehydration of the appropriate amyl alcohols ... 

As noted earlier (Section 4 10) primary carbocations are too high m energy to be intermediates m most chemical reactions If primary alcohols don t form primary car bocations then how do they undergo elimination s A modification of our general mech amsm for alcohol dehydration offers a reasonable explanation For primary alcohols it is... 

Nitdles may be prepared by several methods (1). The first nitrile to be prepared was propionitdle, which was obtained in 1834 by distilling barium ethyl sulfate with potassium cyanide. This is a general preparation of nitriles from sulfonate salts and is referred to as the Pelou2e reaction (2). Although not commonly practiced today, dehydration of amides has been widely used to produce nitriles and was the first commercial synthesis of a nitrile. The reaction of alkyl hahdes with sodium cyanide to produce nitriles (eq. 1) also is a general reaction with wide appHcabiUty ... 

In general, the reactions of the perfluoro acids are similar to those of the hydrocarbon acids. Salts are formed with the ease expected of strong acids. The metal salts are all water soluble and much more soluble in organic solvents than the salts of the corresponding hydrocarbon acids. Esterification takes place readily with primary and secondary alcohols. Acid anhydrides can be prepared by distillation of the acids from phosphoms pentoxide. The amides are readily prepared by the ammonolysis of the acid haUdes, anhydrides, or esters and can be dehydrated to the corresponding nitriles (31). 

Trifluoromethanesulfonic acid is miscible in all proportions with water and is soluble in many polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and acetonitrile. In addition, it is soluble in alcohols, ketones, ethers, and esters, but these generally are not suitably inert solvents. The acid reacts with ethyl ether to give a colorless, Hquid oxonium complex, which on further heating gives the ethyl ester and ethylene. Reaction with ethanol gives the ester, but in addition dehydration and ether formation occurs. 

Dehydration Processing. Dehydration is one of the oldest means of preserving food. Microbes generally do not grow below a minimum water activity, of 0.65 defined as the equiHbrium relative humidity surrounding food ia a sealed container at a given temperature, ie, no microbes can... 

Carboxylic acid hydiazides are prepared from aqueous hydrazine and tfie carboxylic acid, ester, amide, anhydride, or halide. The reaction usually goes poody with the free acid. Esters are generally satisfactory. Acyl halides are particularly reactive, even at room temperature, and form the diacyl derivatives (22), which easily undergo thermal dehydration to 1,3,4-oxadiazoles (23). Diesters give dihydtazides (24) and polyesters such as polyacrylates yield a polyhydrazide (25). The chemistry of carboxyhc hydrazides has been reviewed (83,84). 

The oxidative dehydration of isobutyric acid [79-31-2] to methacrylic acid is most often carried out over iron—phosphoms or molybdenum—phosphoms based catalysts similar to those used in the oxidation of methacrolein to methacrylic acid. Conversions in excess of 95% and selectivity to methacrylic acid of 75—85% have been attained, resulting in single-pass yields of nearly 80%. The use of cesium-, copper-, and vanadium-doped catalysts are reported to be beneficial (96), as is the use of cesium in conjunction with quinoline (97). Generally the iron—phosphoms catalysts require temperatures in the vicinity of 400°C, in contrast to the molybdenum-based catalysts that exhibit comparable reactivity at 300°C (98). 

Organic Reactions. Nitric acid is used extensively ia iadustry to nitrate aHphatic and aromatic compounds (21). In many iastances nitration requires the use of sulfuric acid as a dehydrating agent or catalyst the extent of nitration achieved depends on the concentration of nitric and sulfuric acids used. This is of iadustrial importance ia the manufacture of nitrobenzene and dinitrotoluene, which are iatermediates ia the manufacture of polyurethanes. Trinitrotoluene (TNT) is an explosive. Various isomers of mononitrotoluene are used to make optical brighteners, herbicides (qv), and iasecticides. Such nitrations are generally attributed to the presence of the nitronium ion, NO2, the concentration of which iacreases with acid strength (see Nitration). 

Polymeric OC-Oxygen-Substituted Peroxides. Polymeric peroxides (3) are formed from the following reactions ketone and aldehydes with hydrogen peroxide, ozonization of unsaturated compounds, and dehydration of a-hydroxyalkyl hydroperoxides consequendy, a variety of polymeric peroxides of this type exist. Polymeric peroxides are generally viscous Hquids or amorphous soHds, are difficult to characterize, and are prone to explosive decomp o sition. 

If the drill string becomes differentially stuck, mechanical methods or spotting fluids can be appHed, or the hydrostatic pressure can be reduced (147). In general, penetration of water- or oil-based spotting fluids into the interface between the filter cake and the pipe accompanied by dehydration and cracking results in reduction of differential pressure across the drill string (147,148). Spotting fluids are usually positioned in the open hole to completely cover the problem area. 

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