Aromatics results

Nitrous acid or nitrite salts may be used to catalyze the nitration of easily nitratable aromatic hydrocarbons, eg, phenol or phenoHc ethers. It has been suggested that a nitrosonium ion (NO + ) attacks the aromatic, resulting initially in the formation of a nitro so aromatic compound (13). Oxidation of the nitro so aromatic then occurs ... 

The side-chain alkylation reaction of aromatic hydrocarbons has also been studied using unsaturated aromatic olefins, especially styrene. Pines and Wunderlich 43) found that phenylethylated aromatics resulted from the reaction of styrenes with arylalkanes at 80-125° in the presence of sodium with a promoter. The mechanism of reaction is similar to that suggested for monoolefins, but addition does not take place to yield a primary carbanion a resonance stabilized benzylic carbanion is formed [Reaction (23a, b)j. 

The stabilization conferred by aromaticity results primarily from the much lower energy associated with a set of electrons in molecular orbitals compared... 

Looking at the selectivity differences in greater detail (Table 2.5), the MAB catalyst will prodnce more gas, coke, and LCO and less gasoline and LPG. Gasoline quality is also affected because of the significant decrease in aromatics resulting in a much lower octane number. 

A second type of route from pyrroles to indoles involves construction of a vinylpyrrole suitable for [4 + 2] cycloaddition leading to a dihydro- or tetrahydro-indole (Scheme 19) (80JOC4515, 81T1597). The dihydro systems can be easily aromatized. 2-Nitrovinylpyrroles, which are readily available by condensation of pyrrole-2-carbaldehyde with nitromethane, give fully aromatic indoles on reaction with dienophiles (equation 139) (73JCS(P1)2450). The aromatization results from elimination of nitrous acid and a further dehydrogenation. 

Stereoselective Friedel-Crafts alkylation. 4 Alkylation of benzene with methyl (S)-2-(mesyloxy)propionate, derived from (S)-lactic acid, under Friedel-Crafts conditions (2 equiv. of A1C13) affords methyl (S)-phenylpropionate in 50-80% chemical yield and as high as 97% optical yield. Unfortunately extension to other aromatics results in mixtures of isomeric products. 

Ionic liquids (imidazolium salts) were utilized as green solvents in the Friedlander synthesis. Reactions of o-amino-substituted aromatic carbonyls with a variety of ketones (cyclic, acyclic, aromatic) result in the desired quinolines in uniformly high yield. Conditions are mild and no hazardous acids or bases are used <03JOC9371>. 

Rearrangements of divinylcyclopropanes in which one of the vinyl groups constitutes a part of an aromatic or heteroaromatic system, such as 3 or 6, are also known. The initially formed cycloheptadienes (e.g. 4) isomerizes into conjugation in those cases where a reconstitution of aromaticity results, thus providing cycloheptadienes 5 and 7, respectively, annulated with the aromatic ring. 

The authors may well be correct when concluding that the surprising weakness of inhibition by aromatics results from slow desorption of a product. However, their model and rate equation appear questionable. Like aromatics, hydrogen is also strongly adsorbed, and so is as likely a candidate as toluene for accumulation on the surface. Also, a single-site mechanism is quite improbable with two strongly adsorbed products. Moreover, the "initial" rates were measured at conversions that entailed a decrease of up to 13% in fluid density, an effect not corrected for. Lastly, the trial equation was derived only from rates at low conversion and cannot be relied upon to reflect the behavior of the reaction as it progresses. 

Surfaces with basic sites form enolates from both the aldehydes and ketones, leading to multiple aldol condensations and Michael additions. " Candidate molecules must be enolizable, i.e., contain an a-hydrogen atom. Aldol condensation / Michael addition products cover the range from a,p-unsaturated aldehydes, saturated aldehydes, hydrogenated products (alcohols), and the heavier aromatics resulting from multiple condensations. The presence of coordina-... 

Again, as in Problem 62, look for aromaticity to play a role. Addition of a nucleophile to the nonring carbon gives an aromatic result ... 

Features Slow-evaporating hydrotreated hydrotreating removes unwanted compds. (e.g., sulfur, nitrogen, oxygen), converts unsat. hydrocarbons (olefins, acetylenes, aromatics), results in relatively low odor no more than trace amts, of HAPs Regulatory SARA nonreportable... 

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