Alcohols electrons

Anilines, flammable liquids, unsaturated organics, lactic acid, coal, ammonia, powdered metals, wood, alcohols, electron-rich aromatic rings (phenols, analines)... 

Phenols are less acidic than carboxylic acids, but more acidic than alcohols. Electron-withdrawing groups increase the acidity, but electron-donating groups reduce the acidity. 

Other important features of the reaction were also established. Primary alcohols reacted faster than secondary, which were much more reactive than tertiary alcohols. Electron-withdrawing substituents on the benzene ring of phenyl isocyanate enhanced the reactivity, while electron-releasing groups retarded it. The reaction was faster in non-polar than in polar solvents. Alcohol-solvent association was found when dibutyl ether was the solvent, based on infrared data. This association was considered to reduce the rate primarily by reducing the magnitude ofk. The activation energy for the uncatalysed reaction of phenyl isocyanate with methanol in dibutyl ether was 10 kcal mole , and that for the triethylamine-catalysed reaction was 5 kcal mole . ... 

Figure 5. Determination of enantiomeric purity by enantioselective H-NMR spectroscopy. The N-methyl signals in the H-NMR spectrum obtained from 1.1 mg of indolinospirobenzoxazine 4 in CDClj at 400 MHz are shown. Scales give chemical shifts 5. Left ( (-4) in the presence of 9 equivalents of (Sy 1 -(9-anthryl)-2,2,2-trifluoroethanol. Right Enriched (+ >4 in the presence of 11 equivalents of the same alcohol electronic integration yields an enantiomeric purity of 42 3%.

In benzylic alcohols, electron-withdrawing substituents enhance and electron-releasing ones decrease, the rate of protonolysis, suggesting that the dissociated 9-BBN monomer forms a complex with alcohol which loses Hj. 

The forces determining the solvation of the dyes are of some interest. If solvent-solvent interactions (e.g., hydro-phobic effects) are important, then thionine and proflavin should behave similarly since they have essentially the same size and shape. Inspection of the rates in Table 1 indicates that, compared with thionine, the forward rate for proflavin dimerization is less sensitive to addition of ethanol, but more sensitive to addition of propanol. This suggests the solvation is dependent on dye-alcohol electronic interactions rather than solvent-solvent forces. 

The 0—H itself interacts conjugatively and this interaction is reflected in higher values of intensities as compared with the aliphatic alcohols. Electron-withdrawing groups, by decreasing the electron density of the ring, lead to higher intensities. 

Again like water, alcohols are amphoteric They are both acidic and basic. Complete deprotonation to an alkoxide takes place with bases whose conjugate acids are considerably weaker than the alcohol. Protonation gives an alkyloxonium ion. In solution, the order of acidity is primary > secondary > tertiary alcohol. Electron-withdrawing substituents increase the acidity (and reduce the basicity). 

Disubstituted benzimidazoles could be obtained from arylcarbodiimides in moderate to good yields under Cu(0Ac)2/02 system at 100 °C in one-pot cascade procedure (Scheme 8.53). This copper-catalyzed efficient 1,2-disubstituted benzimidazoles synthesis includes C-H activation/C-N or C-O bond formation. The nucleophiles involve various A/ -nucleophiles and 0-nucleophiles such as amine and alcohol. Electron-donating groups on the arylcarbodiimides accelerate this reaction in contrast to the electron-withdrawing groups [93]. 

The following mechanism appears reasonable (compare Section VI, 12), It assumes that the function of the aluminium ieri.-butoxide, or other alkoxide. is to provide a source of aluminium ions and that the aluminium salt of the secondary alcohol is the actual reactant. Aluminium with its sextet of electrons has a pronounced tendency to accept a pair of electrons, thus facilitating the initial coordination and the subsequent transfer of a hydride ion ... 

As expected, the formation of a carbonyl group is not possible with tert-allylic alcohols. Although the aromatic ring bears electron-donating groups, the 2,2-disubstituted chromene 119 was formed smoothly with the tert-allylic alcohol 118[100]. 

An intramolecular charge transfer toward C-5 has been proposed (77) to rationalize the ultraviolet spectra observed for 2-amino-5-R-thiazoles where R is a strong electron attractor. Ultraviolet spectra of a series of 2-amino-4-p-R-phenylthiazoles (12) and 2-amino-5-p-R-phenylthiazoles (13) were recorded in alcoholic solution (73), but, reported in an article on pK studies, remained undiscussed. Solvent effects on absorption spectra of 2-acetamido and 2-aminothiazoles have been studied (92). 

Organic chemists have devised a number of shortcuts to speed the writing of structural formulas Sometimes we leave out unshared electron pairs but only when we are sure enough m our ability to count electrons to know when they are present and when they re not We ve already mentioned representing covalent bonds by dashes In condensed structural formulas we leave out some many or all of the covalent bonds and use sub scripts to indicate the number of identical groups attached to a particular atom These successive levels of simplification are illustrated as shown for isopropyl alcohol ( rub bmg alcohol )... 

Each carbon has four bonds in ethyl alcohol oxygen and each carbon are surrounded by eight electrons... 

We have seen this situation before m the reaction of alcohols with hydrogen halides (8ection 4 11) m the acid catalyzed dehydration of alcohols (8ection 5 12) and m the conversion of alkyl halides to alkenes by the El mechanism (8ection 5 17) As m these other reactions an electronic effect specifically the stabilization of the carbocation intermediate by alkyl substituents is the decisive factor The more stable the carbo cation the faster it is formed... 

The mechanism by which the Birch reduction of benzene takes place (Figure 118) IS analogous to the mechanism for the metal-ammonia reduction of alkynes It involves a sequence of four steps m which steps 1 and 3 are single electron transfers from the metal and steps 2 and 4 are proton transfers from the alcohol... 

Carboxylic acids are weak acids and m the absence of electron attracting substituents have s of approximately 5 Carboxylic acids are much stronger acids than alcohols because of the electron withdrawing power of the carbonyl group (inductive effect) and its ability to delocalize negative charge m the carboxylate anion (resonance effect)... 

Many of the properties of phenols reflect the polarization implied by the resonance description The hydroxyl oxygen is less basic and the hydroxyl proton more acidic in phenols than m alcohols Electrophiles attack the aromatic ring of phenols much faster than they attack benzene indicating that the ring especially at the positions ortho and para to the hydroxyl group is relatively electron rich... 

Fnedel-Crafts alkylation Alcohols in combination with acids serve as sources of carbocations Attack of a carbocation on the electron rich ring of a phe nol brings about its alkylation... 

Phenols are polar compounds but less polar than alcohols They resem ble arylammes m having an electron rich aromatic ring... 

Pauli exclusion principle (Section 1 1) No two electrons can have the same set of four quantum numbers An equivalent expression is that only two electrons can occupy the same orbital and then only when they have opposite spins PCC (Section 15 10) Abbreviation for pyndimum chlorochro mate C5H5NH" ClCr03 When used in an anhydrous medium PCC oxidizes pnmary alcohols to aldehydes and secondary alcohols to ketones... 

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