Anions amines

The initiating radicals are assumed to be SCN, ONO or N3 free radicals. Tris oxalate-ferrate-amine anion salt complexes have been studied as photoinitiators (A = 436 nm) of acrylamide polymer [48]. In this initiating system it is proposed that the CO2 radical anion found in the primary photolytic process reacts with iodonium salt (usually diphenyl iodonium chloride salt) by an electron transfer mechanism to give photoactive initiating phenyl radicals by the following reaction machanism ... 

The reactivity of the deprotonation product of the amine, the amine anion (R-NH-), can be neglected under the reaction conditions used for N-azo coupling. 

Transport and Binding Proteins Amino acids, peptides, and amines Anions... 

The lactam anion reacts with monomer in the second step of the initiation process by a ring-opening transamidation to form the primary amine anion XXXV. Species XXXV, unlike... 

Cationic polymerization of 4-membered imines (IUPAC azetidines) generally follows the same patterns as the aziridines [Matyjaszewski, 1984a,b Muhlbach and Schulz, 1988]. Imines are generally unreactive toward anionic polymerization presumably because of the instability of an amine anion (which would constitute the propagating species). The exception occurs with V-acylaziridines as a result of the electron deficiency of the nitrogen coupled with the highly strained 3-membered ring. 

Based on the early racemic synthesis of 4 (cis series), it had already been demonstrated that 2-azetidinone ring closure could be achieved via nucleophilic attack of a lithium amine anion on a (3-ester. Cyclization could be accomplished with other strong bases, but sodium bistrimethylsilylamide was found to effect efficient cyclization without significant racemization at C3. During the search for experimentally convenient bases, it was noted that Noyori (Nakamura et al., 1983) reported that tetrabutylammonium fluoride (TBAF) as well as LiF, KF, and CsF could serve as the base in Aldol reactions. Treatment of 17a or 17b with TBAF trihydrate in THF did not affect cyclization. After much experimentation it was found that addition of A,0-bistrimethylacetamide (BSA) to 19 followed by TBAF addition, effected 2-azetidinone ring closure. Further optimization found that use of catalytic TBAF (< 1%) in methylene chloride afforded near quantitative cyclization. 

Substitution of a carbon monoxide ligand of complexes, such as 1, by the more electron-donating triphenylphosphane group (see Section 1.1.1.3.4.1.3.) provides chiral monophos-phane complexes, such as 3. Monophosphane complexes in general lack sufficient electrophilic-ity to react with amines or thiols, but react readily with amine anions at the /J-position, producing enolate anions such as 4, which may be quenched stereoselectively at the a-carbon by electrophiles46 (see Section 1.1.1.3.4.1.3.). The conformational and stereochemical issues involved are essentially identical to those already discussed in this section for the 1,4-additions of carbon nucleophiles. 

The more functionalized /Ta,/ -unsaturated iron-acyl complexes, such as 6, also react regiose-lectively in Michael fashion with amine anions, including the relatively non-nucleophilic lithium diisopropylamide. Stereoselective attack upon the s-cis conformer of 6 by the amine anion from the less hindered face of the inducing iron center generates the fs-cnolatc 7 which may be quenched diastereoselectively (Section 1.1.1.3.4.1.3.). 

A novel azide synthesis using p-toluenesulfonyl azide and amine anions... 

In solution-based polymerization, use of the initiating anionic species allows control over the trans/cis nricrostructure of the diene portion of the copolymer. In solution SBR, the alkyllithium catalyst allows the 1,2 content to be changed with certain modifying agents such as ethers or amines. Anionic initiators are used to control the molecular weight, molecular weight distribution, and the microstructure of the copolymer... 

In practice, the same problems of polyalkylation and E2 elimination exist with the amine anion as with the neutral amine—and as far as E2 goes, much more so. 

Ion exchange benzene sulphonic acid (cation exchange) or quaternary amine (anion exchange). 

Sargeson and his coworkers have developed an area of cobalt(III) coordination chemistry which has enabled the synthesis of complicated multidentate ligands directly around the metal. The basis for all of this chemistry is the high stability of cobalt(III) ammine complexes towards dissociation. Consequently, a coordinated ammonia molecule can be deprotonated with base to produce a coordinated amine anion (or amide anion) which functions as a powerful nucleophile. Such a species can attack carbonyl groups, either in intramolecular or intermolecular processes. Similar reactions can be performed by coordinated primary or secondary amines after deprotonation. The resulting imines coordinated to cobalt(III) show unusually high stability towards hydrolysis, but are reactive towards carbon nucleophiles. While the cobalt(III) ion produces some iminium character, it occupies the normal site of protonation and is attached to the nitrogen atom by a kinetically inert bond, and thus resists hydrolysis. 

Note 2 Amine anions are more likely to be found in pharmaceutical compounds than acids. If acetic acid had not worked, you would add nonyl amine... 

Compared to nitrogen, oxygen is more electronegative and thus holds onto its electrons more tightly. This stabilization of the oxygen anion compared to the amine anion is reflected in the pKa values for alcohols (15-19) compared to the pA., value for amines (35). Therefore, the alkoxide is the better leaving group. 

Metal salts and complexes continue to attract interest as radical/ionic initiators. Trisoxalatoferrate/amine anion salts have been studied as initiators of the polymerization of acrylamide. Here the anion salts react with photolytically formed COa " radicals by an electron transfer mechanism to give photoactive initiating phenyl radicals by the set of reactions shown in Scheme 9. Ferric o-phenanthroline has been shown to be a good photoinitiator for... 

Table 17. Azides from reaction of N2O and amine anions"...

Reactions of this type were first studied by Curtius and co-workers . For example, diethyl malonate and /(-toluenesulphonyl azide reacted in the presence of cold sodium ethoxide to give the sodium salt of the 5-hydroxytrizizole (296) . Acidification gave the 5-triazolone (297) which isomerized to the diazo compound (298) (overall yield 90%). (The same product could be obtained in 85% yield without base by heating the azide and malonate at 100° and a pressure of 20 mm) . This reaction provided the basis for the so-called diazo-transfer reaction, an extremely useful method of synthesizing diazo compounds, which has been reviewed. The reaction has been formulated as shown in equation (134), and has been extended to the synthesis of azides by a diazo transfer to amine anions/i-Toluenesulphonyl azide reacts with hydrazone... 

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