Ethylene hydroxide dehydration

Cyclohexadiene has been prepared by dehydration of cyclohexen-3-ol,3 by pyrolysis at 540° of the diacetate of cyclohexane-1,2-diol,4 by dehydrobromination with quinoline of 3-hromocyclohexene,6 by treating the ethyl ether of cyclohexen-3-ol with potassium bisulfatc,6 7 by heating cyclohexene oxide with phthalic anhydride,8 by treating cyclohexane-1,2-diol with concentrated sulfuric acid,9 by treatment of 1,2-dibromocyclo-hexane with tributylamine,10 with sodium hydroxide in ethylene glycol,10 and with quinoline,6 and by treatment of 3,6-dibromo-cyclohexene with sodium.6... 

The hrst step in the preparation of the antidepressant maprotiline (33-5) takes advantage of the acidity of anthrone protons for incorporation of the side chain. Thus treatment of (30-1) with ethyl acrylate and a relatively mild base leads to the Michael adduct saponihcation of the ester group gives the corresponding acid (33-1). The ketone group is then reduced by means of zinc and ammonium hydroxide. Dehydration of the hrst-formed alcohol under acidic conditions leads to the formation of fully aromatic anthracene (33-2). Diels-Alder addition of ethylene under high pressure leads to the addition across the 9,10 positions and the formation of the central 2,2,2-bicyclooctyl moiety (33-3). The hnal steps involve the construction of the typical antidepressant side chain. The acid in (33-3) is thus converted to an acid chloride and that function reacted with methylamine to form the amide (33-4). Reduction to a secondary amine completes the synthesis of (33-5) [33]. 

The oxazolo[3,2-tf]quinazoline (200) was obtained by cyclization of 3-(2-chloroethyl)quinazoline-2,4-dioine (199) with potassium carbonate (60JCS3551). The same compound was also obtained when ethylene oxide reacted with 2-chloroquinazolin-4-one (201) in the presence of sodium hydroxide (60JCS3551). 3-Acylalkylquinazoline-2,4-diones (201) underwent intramolecular dehydrative cyclization upon heating with polypho-phoric acid to 203 [89IJC(B)274]. 

Irritant dermatitis does not involve an immune response and is typically caused by contact with corrosive substances that exhibit extremes of pH, oxidizing capability, dehydrating action, or tendency to dissolve skin lipids. In extreme cases of exposure, skin cells are destroyed and a permanent scar results. This condition is known as a chemical burn. Exposure to concentrated sulfuric acid, which exhibits extreme acidity, or to concentrated nitric acid, which denatures skin protein, can cause bad chemical bums. The strong oxidant action of 30% hydrogen peroxide likewise causes a chemical bum. Other chemicals causing chemical bums include ammonia, quicklime (CaO), chlorine, ethylene oxide, hydrogen halides, methyl bromide, nitrogen oxides, elemental white phosporous, phenol, alkali metal hydroxides (NaOH, KOH), and toluene diisocyanate. 

Manufacture of the polyols is usually carried out in the same reactors as for ethoxylates. The first step is to dissolve sodium hydroxide in propylene glycol and warm to 120°C. The required amount is charged to the reactor, dehydrated and padded with nitrogen. Once this is achieved propylene oxide is added as fast as it will react, maintaining the temperature at 120°C until the required molecular weight is reached. Then ethylene oxide is added at a rate, which maintains the temperature at 120°C. When all the ethylene oxide is added, the... 

Styrenes are available by dehydration of either a-arylethyl or /S-aryl-ethyl alcohols. The procedures were reviewed in 1S>49. /S-Phenylethyl alcohol loses water at 140° over a roixture of molten sodium and potassium hydroxides to give styrene, C,H5CH=CH2, in 57% yield. The 2,4-dimethyI derivative has been prepared in a similar manner from the primary alcohol. " Many substituted styrenes have been made by dehydration of methylarylcarbinols with potassium hydrogen sulfate, phosphorus pentoxide, or activated alumina. 1,1-Diphenyl-ethylene and 2-phenyl-2-butene are easily obtained by boiling the corresponding tertiary alcohols with dilute sulfuric acid. 

By altering the mode of preparation of alumina catalysts in such a way that the molecular porosity was affected, Adkins 40 has been able to activate preferentially the catalyst for either decarboxylation or dehydration. This was experimentally accomplished by forming aluminum hydroxide and hydrated alumina by precipitation from salts or esters in water or xylene solution and by preparation by the action of water vapor on aluminum alk-oxides, pure and supported on pumice. Variation in ethylene efficiency" from 34 to 150 was obtained in the different catalysts. On the basis of the results, Adkins advanced the hypothesis that molecular porosity of the catalysts determined the directional activity and that large pores favored decarboxylation and small pores dehydration reactions. 

Alumina has found wide application in GSC. It is a highly polar material with a typical surface area of 250 m g . It interacts strongly with polar molecules such as water, and also has some catalytic activity, for example, it may convert acetone to diacetone alcohol or dehydration may occur. Much of the early work on alumina was carried out by Scott who subsequently concentrated his research on surface modified materials [37,38]. He measured polarity in terms of the retention of ethylene relative to non-polar ethane and propane. Activation by heating at temperatures up to 500°C increased the polarity by loss of water and adsorption of water reduced polarity until a minimum was reached when the amount required for a monolayer had been adsorbed. Further water continued to reduce the activity (by reducing the surface area) but increased the polarity [39-41]. Scott later extended his work on alumina to substances modified with sodium hydroxide and obtained results similar to those obtained for the water-modified alumina without the need to presaturate the carrier gas. Retention of benzene relative to heptane increased markedly on alumina modified with sodium salts in the order OH > Cl > Br > I . A recent comparative study of the modifier effects alkali... 

Acetic anhydride I potassium hydroxide Preferential dehydration of alcohols frans-Ethylene derivatives from alcohols... 

Flame retardance of ethylene-vinyl acetate copolymer can be achieved using magnesium hydroxide incorporated in the polymeric matrix. The adduct of a small amount of zinc borate as synergistic agent in the formulation increases the fire-proofing properties. Multinuclei solid-state NMR appears as a means to characterise materials before and after combustion. It was shown that endothermic dehydration, water vapour evolved and formation of a glassy coating provided the flame retardancy of interest to the polymer matrix. 12 refs. EUROPEAN COMMUNITY EUROPEAN UNION FRANCE WESTERN EUROPE... 

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