Ethenol

To a hot solution of 20.6 g of sodium in 400 ml of absolute ethanol, there is added a solution of 110 g of phthalide and 110 g of p-methoxybenzaldehyde. A vigorous reaction ensues and one-helf of the alcohol is distilled off over a two hour period. Ice and water are added to the red solution end the diluted solution is ecidified with hydrochloric acid. The resulting gum solidifies end the aqueous phase is removed by decantation. The crude solid is recrystallized twice from two liters of ethenol yielding 2-(p-methoxyphenyl)-1,3-indandione as pale yellow crystals, MP155°-156°C. 

A mixture of 3 gof 8-(2-hydroxy-3-chloropropoxy)-5-methyl coumarin,4.3 g of t-butylamine and 60 ml of ethenol Is heated et 100°C in a sealed tube for 15 hours. The reaction mixture is concentrated under reduced pressure to dryness. The residue Is recrystallized from a mixture of ethanoi and ether to give 2.1 g of the desired product melting at 226° to 228 C (with decomposition). 

A warm solution of 6.5 g (0.02 mol) of 6-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo-[13-a] [1,4] -benzodiazepine in 30 ml of ethenol wes combined with a warm solution of 2.6 g (0.022 mol) of maleic acid in 20 ml of ethenol. The mixture was diluted with 150 ml of ether and heated on the steam bath for 3 minutes. After cooling, the crystals were collected, washed with ether and dried in vacuo to yield 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazoM, 5-a] [1,4] -benzodiazepine maleete, melting point 148°C to 151°C. 

What kind of chemistry do enols have Because their double bonds are electron-rich, enols behave as nucleophiles and react with electrophiles in much the same way that aikenes do. But because of resonance electron dona lion of a lone-pair of electrons on the neighboring oxygen, enols are more electron-rich and correspondingly more reactive than aikenes. Notice in the following electrostatic potential map of ethenol (BbC CHOH) how there is a substantial amount of electron density (yellow-red) on the a carbon. 

Investigation of stable simple enols has recently been undertaken with a series of p,P-dimesityl-a-ethenols [29] and [30] in which Mes = 2,4,6-tri-methylphenyl. In this work, 5(OH) and /hcoh were measured for a series of compounds with various a-substituents and in a range of solvents (Biali and Rappoport, 1984 Rappoport et al., 1988). The nmr parameters were shown to be linearly related to the Kamlet and Taft P-variable, a solvent property that is related to its ability to act as a hydrogen-bond acceptor (Kamlet and Taft, 1976 Taft et al., 1985). 

CA s policy for naming acetylenic, acrylic, methacrylic, ethylenic, and vinyl polymers is to use the source-based method, and source-based representation is used to depict the polymers graphically thus, a synonym for polyethylene is polyethylene and not poly(1,2-ethanediyl) a synonym for polypropylene is polypropylene, and poly(vinyl alcohol) is named ethenol homopolymer although ethenol does not exist. Thus, these polymers are named and represented structurally by the source-based method, not the structure-based method. 

The mp was 196° (6° per minute rise). This styphnate is much more useful than picrate as a hexamine derivative largely because Amm Styphnate is sol in water or water-ethenol. 

Alkynes, unlike alkenes, are not hydrated readily in aqueous acid unless a mercuric salt is present as a catalyst. Also, the products that are isolated are either aldehydes or ketones instead of alcohols. Even though the addition of one molecule of water to ethyne probably gives ethenol (vinyl alcohol) initially, this compound is unstable relative to its structural isomer (ethanal) and rapidly rearranges ... 

Exercise 10-20 Show how the rearrangement of ethenol to ethanal could take place in aqueous solution with water behaving as both a proton acceptor (base) and a proton donor (acid). 

The simplest unsaturated alcohol, ethenol (vinyl alcohol), is unstable with respect to ethanal and has never been isolated (see Sections 10-5A and 13-5B) ... 

The cr-dimethylacetal complex (40) is then hydrolyzed on passage through an alumina column, producing the cr-acetaldehyde complex (38) which is converted to the 7r-vinyl alcohol complex (39) by protonation. Wakatsuki, Nojakura, and Murahashi reported the synthesis of l,3-bis(7r-ethenol)2,4-dichloro- i-dichloroplatinum(II) (41) (42), however, Thyret, who recently reported the NMR evidence for the formation of tetracarbonyl(7r-ethenol)iron (42) at low temperature, could not reproduce the synthesis of (41) (43). 

A stable, readily soluable platinum ir-vinyl alcohol complex has now been synthesized and well characterized. Initially, this compound, chloro(acetylacetonato)(ir-ethenol)platinum(II) (45), was synthesized from the ir-ethylene compound (43) via a vinyl trimethylsilyl ether complex (44) using the same general procedure employed in the synthesis of (41) and (42) (44). 

Fig. 7. Bond distances in chloro(acetylacetonato)(ir-ethenol)platinum(II) (47).

On the other hand, an intramolecular reversible rotation of the two mesityl rings in 2,2-dimesityl-l-(trimethylsilyl)ethenol (202) occurs to give 203 (equation 83)258. The free energy of activation for the rotation (AG ) leading to the enantiomerization is... 

Scheme 37 Stepwise mechanism computed for the reaction between ethenol (147) and chloro-sulfonyl isocyanate (148)...

The reported halflife of ethenol (vinyl alcohol) in the gas phase at room temperature is ca. 30 min [221], far shorter than our calculated 1028-1029 s. However, the 30 min halflife is very likely that for a protonation/deprotonation isomerization catalyzed by the walls of the vessel, rather than for the concerted hydrogen migration (Fig. 5.30) considered here. Indeed, the related ethynol has been detected in planetary atmospheres and interstellar space [222], showing that that molecule, in isolation, is long-lived. Even under the more confined conditions of the lab, ethenol can be studied in the gas phase [221, 223] and in solution [224]. All three methods predict very long halflives for the uncatalyzed reaction. 

Fig. 6.3 Geometries (A, degrees) and relative energies (kJ mol ) for four reactions, the same as for the ab initio calculations of Fig. 5.21 most Hs are omitted, for clarity. In Fig. 5.21, raw energies in hartrees and ZPEs were given. The experimental relative energies [96] are somewhat approximate for the ethenol (vinyl alcohol) and cyclopropylidene reactions...

Figure 6.9 shows charges and bond orders calculated for an enolate (the conjugate base of ethenol or vinyl alcohol) and for a protonated enone system (protonated... 

Malachite green oxalate A 1% ethenolic potassium hydroxide solution is sprayed, and the plate is heated (150°C, 5 min) and further sprayed with a buffered (pH = 7) water/acetone solution of malachite green oxalate to yield white spots on a blue background. 

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