Replacement of N-hydrogen

Sodium hypochlorite acetic acid Replacement of N-hydrogen by N-chlorine NH NCI... 

First examine the geometry of methyl radical. Is it planar or puckered Examine the geometries of 2-methy 1-2-propyl radical, trifluoromethyl radical, trichloromethyl radical and tricyanomethyl radical. Classify each of the substituents (methyl, fluoro, chloro and cyano) as a n-electron donor or as a Tt-electron acceptor (relative to hydrogen). Does replacement of the hydrogens by 7t-donor groups make the radical center more or less puckered Does replacement by Jt-acceptor groups make the radical center more or less puckered Justify your observations. 

Griess (1860) coined the prefix diazo for the nitrosation product of an aromatic amine, because he assumed that two nitrogen atoms replaced two hydrogen atoms of the parent aromatic compound. On the other hand, azobenzene received its name on the basis of the C H N ratio 6 5 1, indicating the replacement of one hydrogen by one nitrogen atom. 

Consistent with the experimental data, mutation of the purine base nitrogens, i.e. N, 3N, 7N and 9N, showed that replacement of N, 3N and 9N with CH had little effect on binding affinity whereas a similar replacement of 7N led to a loss of 2.8 kcal/mol. The 0.6 kcal/mol gain in affinity for the 1-deaza and 3-deaza AMP analogues was consistent with the hydrophobic nature of this portion of the binding site cavity and the absence of hydrogen bond donors in the vicinity of either heteroatom. 

M. Shi and Y.-L. Shi reported the synthesis and application of new bifunctional axially chiral (thio) urea-phosphine organocatalysts in the asymmetric aza-Morita-Baylis-Hillman (MBH) reaction [176, 177] of N-sulfonated imines with methyl vinyl ketone (MVK), phenyl vinyl ketone (PVK), ethyl vinyl ketone (EVK) or acrolein [316]. The design of the catalyst structure is based on axially chiral BINOL-derived phosphines [317, 318] that have already been successfully utilized as bifunctional catalysts in asymmetric aza-MBH reactions. The formal replacement of the hydrogen-bonding phenol group with a (thio)urea functionality led to catalysts 166-168 (Figure 6.51). 

Treatment of pyridine with NaOD/D20 at elevated temperatures results in eventual replacement of all hydrogen atoms by deuterium. This process presumably involves deprotonation followed by rapid deuteration of the intermediate negatively charged species (cf. equation 21) in a sequential manner. Azine N- oxides are deuterated in a similar way, positions adjacent to the N- oxide exchanging particularly rapidly. Controlled deprotonation of ring carbon atoms a and y to the heteroatom can be accomplished by the use of strong, non-nucleophilic bases and the intermediate carbanions may be trapped by electrophiles (equation 27). The yields in these reactions are in most cases only moderate, however. As expected, deprotonation occurs more easily if the heteroatom is positively charged. 

Salt, n. A compound formed by the replacement of the hydrogen of an acid by the metal of a base. Popular name of sodium chloride. 

Metalating agent. n-Butyllithium is one of the most useful agents for the replacement of aromatic hydrogen in ethers, usually ortho to the ether function tetrahydro-furane is generally preferred as solvent, but ether is often used. For example, 1,7-dimethoxynaphthalene yields the 6-Li derivative, convertible into the corresponding methyl and carboxy compounds. ... 

Structure-Activity Relationships. Effects caused by initial structural modifications in the lead compound are shown in Table I. Replacement of the oxygen in 1 with sulfur caused complete loss of activity. Replacement of the phenyl moiety at the 2-position with benzyl, hydrogen, or alkyl gave inactive analogs ( -9 Similary, replacement of N-phenyl with hydrogen, alkyl,... 

S. J. Miller (Chevron) published results from early work that highlighted the selectivity of the platinum form of SAPO-11 catalyst compared to a number of others. These others were amorphous silica-alumina, from which one would expect little or no selectivity, ZSM-5, HY, and Na-Beta zeolites. All the catalysts carried 1 wt. % platinum and the feed employed was n-octane. He found that at 30% conversion, only SAPO-11, the amorphous silica-alumina, and the HY catalysts exhibited better than 94% selectivity for feed isomerization to isooctanes. ZSM-5 and Na-Beta catalysts behaved poorly in this regard. Selectivity for dimethylhexanes was low. SAPO-11 also produced equal quantities of 2- and 3-methyl heptanes, whereas the other catalysts favored 3-methyl heptane, with a ratio close to that favored by thermodynamics. SAPO-11 also produced one of the lowest levels of doubly-branched hexanes (Table 10.1646) and the predominant ones formed were those separated by more than one carbon—only minor amounts of the less thermally stable (bond breaking here can produce tertiary carbonium ions) geminal-dimethyl (2,2 and 3,3-) ones were formed. Noble metal presence was a key to success since replacement of the hydrogenation metal platinum by pallodium did not alter the isomeri-zation selectivity much, but replacement by nickel led to very poor isomerization. 

The reaction brings about the replacement of the hydrogen in the NH group by the nitroso group (N = 0). Nitroso-dimethyl-amine, is formed as a light yellow, insoluble liquid when sodium nitrite is added to an acidified aqueous solution of a salt of dimethylamine. 

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