Alcohols, dehydration dehydrating agents

Uses Unsat. polyester resin comonomer solvent, plasticizer in vinyl, polyester, and polyurethane resins plasticizer for polyvinyl alcohol dehydrating agent for natural gas solvent, lubricant for textile dyeing/printing solvent for printing inks, dyes, cosmetics, pharmaceuticals extraction solvent humectant for tobacco, printing inks, cork chem. intermediate plasticizer in food-contact polymers and coatings in food-pkg. adhesives in cellophane for food pkg. in surf, lubricants for mfg. of food-conta[Pg.4521]

At temperatures of 220-240 C it functions as an efficient, neutral dehydrating agent, amides yielding nitriles and alcohols yielding alkenes. 

McjC = CHCOCH3. Colourless liquid b.p. 129"C, with a strong peppermint-like odour. Prepared by distilling diacetone alcohol in the presence of a trace of iodine. Converted to phorone by heating in propanone with dehydrating agents such as sulphuric acid. It is a solvent For cellulose acetate and ethyl-cellulose and other polymers. 

CaHjNCO, PhNCO. A pungent lachrymatory almost colourless liquid m.p. — 33 "C, b.p. 162°C. Used as a dehydrating agent and for characterization of alcohols. Prepared from aniline and phosgene in the presence of hydrogen chloride. 

Directly from the corresponding acid and alcohol, in the presence of a dehydrating agent. Thus when ethanol and acetic acid are mixed, ethyl acetate and water are formed, but in addition an equilibrium is established. 

The widely used Moifatt-Pfltzner oxidation works with in situ formed adducts of dimethyl sulfoxide with dehydrating agents, e.g. DCC, AcjO, SO], P4O10, CCXTl] (K.E, Pfitzner, 1965 A.H. Fenselau, 1966 K.T. Joseph, 1967 J.G. Moffatt, 1971 D. Martin, 1971) or oxalyl dichloride (Swem oxidation M. Nakatsuka, 1990). A classical procedure is the Oppenauer oxidation with ketones and aluminum alkoxide catalysts (C. Djerassi, 1951 H. Lehmann, 1975). All of these reagents also oxidize secondary alcohols to ketones but do not attack C = C double bonds or activated C —H bonds. 

Perchloric acid Acetic acid, acetic anhydride, alcohols, antimony compounds, azo pigments, bismuth and its alloys, methanol, carbonaceous materials, carbon tetrachloride, cellulose, dehydrating agents, diethyl ether, glycols and glycolethers, HCl, HI, hypophosphites, ketones, nitric acid, pyridine, steel, sulfoxides, sulfuric acid... 

The fact that the amount of total linalol decreases whilst the richness in linalyl acetate increases, proves that linalol appears in the plant at an earlier period than its acetic ester. Further, the free acetic acid acting on the linalol esterifies a portion of it, whilst another portion of this terpene alcohol is dehydrated, with the production of limonene and. dipentene, which are the usual resultants of linalol in presence of certain dehydrating agents. This view is corroborated by the fact that the quantity of the mixed terpenes increases during the esterification, without the slightest variation being observed in the ratio between the... 

The resulting 4-methylhexanone-2 oxime separates and is dried by any suitable means, such as with a dehydrating agent, for example, sodium sulfate or magnesium sulfate. After drying, 4-methylhexanone-2 oxime is reduced with hydrogen by means of a catalyst, such as Raney nickel, or by reaction of sodium and a primary alcohol, such as ethanol. The resulting 2-amino-4-methylhexane may be purified by distillation, as described in U.S. Patent 2,350,318. 

Another way to esterify a carboxylic acid is to treat it with an alcohol in the presence of a dehydrating agent. One of these is DCC, which is converted in the process to dicyclohexylurea (DHU). The mechanism has much in common with the nucleophilic catalysis mechanism the acid is converted to a compound with a better leaving group. However, the conversion is not by a tetrahedral mechanism (as it is in nucleophilic catalysis), since the C—O bond remains intact during this step ... 

An accident of the same nature happened when it was dried with diphosphorus pentoxide. In this case, it is unlikely that the reason for it is the formation of an acetylene salt. The author believes that, since water plays a desensitising role on this compound, it leads to a very unstable pure alcohol when it is removed by strong dehydrating agents. The temperature rise due to the dessicating agent hydration is sufficient to decompose the pure alcohol violently.This interpretation could also be applied to the previous case. 

This reaction is run by heating the alcohol in the presence of concentrated sulfuric acid, a good dehydrating agent. Diethyl ether, CH,CH2OCH2CH3, was formerly used as an anesthetic in surgery, but it caused undesirable side effects in many patients, and was replaced by other types of agents. 

Alcohols form alkenes in an elimination reaction when reacted with dehydrating agents. 

AEC is soluble in alcohol and clearing agents, and must be mounted in aqueous mounting media. All other substrates are not soluble in alcohol or clearing agents. They may be dehydrated, cleared, and permanently mounted. These substrates can be used as single labels or to introduce multiple colors in a tissue section as shown for instance in Fig. 6.1 (see Chap. 7). 

Hydrogen chloride reacts most difficultly, and here it is necessary (as, for example, in the preparation of methyl and ethyl chloride) to use a dehydrating agent, preferably zinc chloride, or, as in the case of the higher alcohols, to heat under pressure in a sealed vessel. 

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