Amines/amine groups

In sorn e situation s, using this option m ay he im portan t. For exam -pic, if p orbitals on electronegative atoms irileracL with d orbitals, (as for a silicon atom bonded to an amine group), you may want to include d orbitals. 

Note that for 4.42, in which no intramolecular base catalysis is possible, the elimination side reaction is not observed. This result supports the mechanism suggested in Scheme 4.13. Moreover, at pH 2, where both amine groups of 4.44 are protonated, UV-vis measurements indicate that the elimination reaction is significantly retarded as compared to neutral conditions, where protonation is less extensive. Interestingy, addition of copper(II)nitrate also suppresses the elimination reaction to a significant extent. Unfortunately, elimination is still faster than the Diels-Alder reaction on the internal double bond of 4.44. 

Clearly, the use of diamine 4.43 as a coordinating auxiliary is not successful. However, we anticipated that, if the basicity of the tertiary amine group of the diamine could be reduced, the elimination reaction will be less efficient. We envisaged that replacement of the tertiary amine group in 4.43 by a pyridine ring might well solve the problem. 

This resonance stabilization is lost when the amine group becomes protonated and o-cyanoaniline is therefore a weaker base than aniline... 

Arylamines contain two functional groups the amine group and the aromatic ring they are difunctional compounds The reactivity of the amine group is affected by its aryl substituent and the reactivity of the ring is affected by its amine substituent The same electron delocalization that reduces the basicity and the nucleophilicity of an arylamme nitrogen increases the electron density in the aromatic ring and makes arylamines extremely reactive toward electrophilic aromatic substitution... 

Ammo acids are classified as a p 7 and so on according to the location of the amine group on the carbon chain that contains the carboxylic acid function... 

Glycine is the simplest ammo acid and the only one m Table 27 1 that is achiral The a carbon atom is a chirality center m all the others Configurations m ammo acids are normally specified by the d l notational system All the chiral ammo acids obtained from proteins have the l configuration at their a carbon atom meaning that the amine group IS at the left when a Fischer projection is arranged so the carboxyl group is at the top... 

In transamination an amine group is transferred from L glutamic acid to pyruvic acid An outline of the mechanism of transamination is presented m Figure 27 4... 

Nylon 6, 11, and 12. This class of polymers is polymerized by addition reactions of ring compounds that contain both acid and amine groups on the monomer. 

Organic compounds containing a hydroxyl, carbonyl, or amine functional group adjacent to a hydoxyl or carbonyl group can be oxidized using metaperiodate, 104 , as an oxidizing titrant. 

If a polyamide is prepared in the presence of a large excess of diamine, the average chain will be capped by an amine group at each end ... 

Reaction (5.N) describes the nylon salt nylon equilibrium. Reactions (5.0) and (5.P) show proton transfer with water between carboxyl and amine groups. Since proton transfer equilibria are involved, the self-ionization of water, reaction (5.Q), must also be included. Especially in the presence of acidic catalysts, reactions (5.R) and (5.S) are the equilibria of the acid-catalyzed intermediate described in general in reaction (5.G). The main point in including all of these equilibria is to indicate that the precise concentration of A and B... 

This polymerization is carried out in the two stages indicated above precisely because of the insolubility and infusibility of the final product. The first-stage polyamide, structure [IX], is prepared in polar solvents and at relatively low temperatures, say, 70°C or less. The intermediate is then introduced to the intended application-for example, a coating or lamination-then the second-stage cyclization is carried out at temperatures in the range 150-300°C. Note the formation of five-membered rings in the formation of the polyimide, structure [X], and also that the proportion of acid to amine groups is 2 1 for reaction (5.II). 

When the proportion of acid to amine groups is reversed-namely, l 2--a process rather similar to reaction (5.II) yields a polymer which ultimately contains the five-membered imidazole ring. This reaction is also carried out in the stages listed below and illustrated by reaction (5.JJ) ... 

Hoffman Degradation. Polyacrylamide reacts with alkaline sodium hypochlorite [7681-52-9], NaOCl, or calcium hypochlorite [7778-54-3], Ca(OCl)2, to form a polymer with primary amine groups (58). Optimum conditions for the reaction include a slight molar excess of sodium hypochlorite, a large excess of sodium hydroxide, and low temperature (59). Cross-linking sometimes occurs if the polymer concentration is high. High temperatures can result in chain scission. 

The amine group of 3-arninoben2otrifluoride can be replaced by Cl, Br, I, F, CN, or OH groups by standard dia2oti2ation reactions. Phosgenation gives 3-trifluoromethylphenyhsocyanate [329-01-1/, which can then be converted to the selective herbicide fluometuron [2164-17-2] a substituted urea. Application. 

The available free carboxyl groups of the DAS—HMS can be linked via a peptide bond to available primary amine groups onto highly antigenic carriers using a carbodiimide (19). The carriers used in this case were bovine semm albumin (BSA) and poly-L-lysine (molecular weight 150,000 to 300,000). The... 

Acryhc stroag base anion exchangers (9) are synthesized from acryhc weak base resias. The tertiary amine groups are coaverted to a quaternary ammonium fuactioaahty by reactioa of chloromethane [74-87-3], CH Cl, and the weak base resia. 

Browning Reactions. The fluorescent components formed in the browning reaction (8) of peroxidized phosphatidylethanolamine are produced mainly by interaction of the amine group of PE and saturated aldehydes produced through the decomposition of fatty acid hydroperoxides. 

The biochemical basis for the toxicity of mercury and mercury compounds results from its ability to form covalent bonds readily with sulfur. Prior to reaction with sulfur, however, the mercury must be metabolized to the divalent cation. When the sulfur is in the form of a sulfhydryl (— SH) group, divalent mercury replaces the hydrogen atom to form mercaptides, X—Hg— SR and Hg(SR)2, where X is an electronegative radical and R is protein (36). Sulfhydryl compounds are called mercaptans because of their ability to capture mercury. Even in low concentrations divalent mercury is capable of inactivating sulfhydryl enzymes and thus causes interference with cellular metaboHsm and function (31—34). Mercury also combines with other ligands of physiological importance such as phosphoryl, carboxyl, amide, and amine groups. It is unclear whether these latter interactions contribute to its toxicity (31,36). 

Tannate Complexation. Certain dmgs, those that contain amine groups, complex readily with tannic acid. Such complexes release the dmg gradually and uniformly. The rate seems to be affected by the pH and the electrolytes present in the gastrointestinal tract. At lower pH, the dmg is released more quickly. Other complexing compounds have also been used. 

Most elastomers that are used for nylon modification contain a small amount of maleic anhydride (0.3 to 2%). In the melt blending process, these elastomers react with the primary amine end groups in nylon, giving rise to nylon grafted elastomers. These grafts reduce the interfacial tension between the phases and provide steric stabili2ation for the dispersed mbber phase. Typically, thermally stable, saturated mbbers such as EPR, EPDM, and styrene—ethylene/butylene—styrene (SEBS) are used. 

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