Nitrogen aromatic

H-Bond Acceptor (HBA) Acyl chlorides Acyl fluorides Hetero nitrogen aromatics Hetero oj gen aromatics Tertiary amides Tertiary amines Other nitriles Other nitros Isocyanates Peroxides Aldehydes Anhydrides Cyclo ketones Ahphatic ketones Esters Ethers Aromatic esters Aromatic nitriles Aromatic ethers Sulfones Sulfolanes... 

Arguing that the MNDO method is more suitable than the AMI method for predicting the heats of formation of five-membered nitrogenated aromatic rings, Garcia and Vilarrasa (88H1803) calculated that 4-fluoroimidazole 14a (R = F, = H) is 2.5 kJ mol more stable than its tautomer 14b,... 

In a study of the lithium aluminum hydride reduction of a series of nitrogen aromatic heterocyclics, Bohlmann97 found that this metal hydride effected a conversion of acridine to 9,1O-dihydroacridine (91) in high yield and purity. The ultraviolet spectrum of the isolated dihydroacridine (Amax 288 mp, loge = 4.18) was confirmed by Braude et al.92 as a part of a study of the hydride donor properties of a series of aromatic nitrogen-heterocycles. These workers found that the dihydroacridine underwent a slow oxidation to acridine in air and a rapid hydrogen transfer in the presence of chloranil to form the quinol and acridine. The dihydroacridine was, however, quite stable under dry nitrogen. 

Mo et al [41] show that the poisoning power of a nitrogen aromatic (polar) compound i primarily determined by a balance between its heaviness or size and basicity. The former may be measured by molecular weight, the latter by proton affinity. 

The following reactions proceed with the participation of the allylic boron system (i) allylboration and protolytic cleavage of organic compounds with multiple bonds, (ii) allylboron-alkyne condensation,598 599 (iii) reductive mono-and trans-a,a -diallylation of nitrogen aromatic compounds, (iv) disproportionation processes between tribut-2-enylborane and BX3 (X = C1, Br, OR, SR). Allylboration of carbonyl compounds, thioketones, imines, or nitriles leads to the homoallylic alcohols, thiols, or amines (Equations (136) and (137). It is most important that 1,2-addition to aldehydes and imines proceeds with high diastereoselectivity so that ( )-allylic boranes and boronates give the anti-products, while -products are formed preferentially from (Z)-isomers. 

Y. Ikeura, K. Kurihara, T. Kunitake, Molecular Recognition at the Air-Water Interface. Specific Binding of Nitrogen Aromatics and Amino Acids by Monolayers of Long-Chain Derivatives of Kemp Acid , J. Am. Chem. Soc., 113, 7342 (1991)... 

Alkyl amines such as methylamine, CH3NH2, or n-propylamine, CH3CH2CH2NH2, are stronger bases than ammonia because the alkyl groups are electron donors and increase the effective electron density on nitrogen. Aromatic amines, on the other hand, are weaker bases than ammonia. Delocalization of the unshared pair of electrons on nitrogen onto the aromatic ring means the electrons are not available to be shared with an acidic proton. 

M. Novotny, R.Kump, F. Merli, and L.J.Todd, Capillary Gas Chromatography/Mass Spektro-metric Determination of Nitrogen Aromatic Compounds in Complex Mixtures, Anal. Chem. 1980, 52, 401-406. 

The concept of chemical catalysis is applied when an electrochemical regeneration process is involved and proceeds through the formation of an adduct that decomposes before or after an additional electron transfer. The electron may be transferred either directly from the electrode or by indirect means in solution from a reducing (or oxidizing) species to regenerate one member of the catalyst couple P/Q. The indirect reduction of acidic protons in the presence of nitrogen aromatic heterocycles may provide a good example. 

Transport of reactants to catalyst. To supply the catalyst with fresh reactant, several mass transfer steps are involved. The hydrogen must first transfer through the gas-liquid interface before it is in the bulk liquid phase. Then, dissolved hydrogen and oil reactant (sulfur, nitrogen, aromatics) in the bulk phase transfer through the liquid film around the catalyst to its outer surface. Finally, the reactants diffuse into the catalyst pores. 

A bicyclic nitrogenous aromatic ring system (known as an indole ring) is attached to the /6-carbon of alanine to form the R-group of tryptophan. Tryptophan is a precursor of serotonin, melatonin, nicotinamide, and many... 

Although Chichibabin reactions arc usually run under heterogeneous conditions in aprotic solvents, such as xylene or iV,A/-dimethylaniline at high temperature, a large number of nitrogen aromatic heterocycles can be aminated under homogeneous conditions in liquid ammonia at low temperature. These two conditions will be discussed separately. 

The effectiveness of an oxidant is dependent upon the oxidation-reduction potential of the intermediate a-adduct and the oxidant (Scheme 10) (76RCR454). For the sake of simplicity, pyridine is used to represent a TT-deficient nitrogen aromatic heterocycle. When the a-adduct is formed readily (k, k i) and hydride elimination is facile (kj is large), the product is formed easily. In cases where the adduct formation is facile (k, k.J but hydride elimination is very slow (kj is small), the reaction proceeds to the stage of a-adduct formation and stops there. When [Pg.10]

The organolithium addition to pyridines or other nitrogen aromatic heterocycles is a well-established general synthetic method. It is usually used to achieve overall substitution on the ring, via lithium hydride elimination or oxidation of the dihydrointermediate [18]. 

Tetramethyl pyridazine-3,4,5,6-tetracarboxylate, but not 3,6-dichloropyridazine or dimethyl phthalazine-l, 4-dicarboxylate, takes part in a Diels-Alder reaction with indole under very concentrated conditions (Scheme 31). The adduct produced after elimination of nitrogen aromatizes by ring opening and the resultant aniline attacks the adjacent ester group to give the phenanthridone... 

Aromatic selenoamides. NaSeH pi situ in refluxing ethanol to achieve the ir Reduction of nitrogenous aromatic t... 

Reduction of nitrogenous aromatic compounds. Nitro-, nitroso- and dinitro-soarenes are reduced to the anilines in 70-94% yield. 

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