Group 15 amides salts

Reactions of the carboxyl group include salt and acid chloride formation, esterification, pyrolysis, reduction, and amide, nitrile, and amine formation. Salt formation occurs when the carboxyUc acid reacts with an alkaline substance (22)... 

The amido ligand is isoelectronic with the alkyl and alkoxo groups and has the possibility to exhibit N-M ir-interactions in order to stabilize the systems they form. Different synthetic reactions are used to prepare mono-Cp titanium derivatives containing amido ligands. These compounds are normally synthesized by (i) the action of the corresponding amide salt on Cp TiCl3, (ii) displacement of amine from a homoleptic amido titanium compound by a Cp reagent, (iii) dehalosilylation reactions, and (iv) elimination of alkane by reaction of an alkyltitanium compound with amine. 

Two research groups studied the syntheses of 36 different macrocycles (Atkins et al., 1978 Rasshofer et al., 1976). The yields averaged about 60% but varied from 7% to 90%. The yields of certain macrocycles prepared by both research groups varied by as much as 50%. These variations can be attributed to different reaction conditions, particularly in the methods used to prepare the amide salts, reaction temperatures, purity of starting materials, and reaction times. Careful drying of the solvent and prevention of atmospheric moisture from contacting the moisture sensitive amide salts generally increases the yields for the cyclization step in these reactions (Bhula et al., 1988). 

If pyridazine is substituted at the 4-position, amination occurs at C-5 for example, 30a gives 31a in a 38% yield (variant 1). In the presence of an oxidant, electron-withdrawing groups facilitate oxidative amination of pyridazines and thus push the reaction even in the absence of amide salt. In liquid NH3,4-nitropyridazine gives 5-amino-4-nitropyridazine in an excellent 98% yield, while the nitropyridazine 30b gives the amino adduct 31b in 93% yield (variant 2). 

The salt effect may also vary according to the lyotropic (Hofineister s) series. For instance, peptide groups are more solubilized ( salted in ) by iodide, perchlorate, thiocyanate, and acetate anions than by lithium, potassium, or cesium cations. That probably reflects the competition between ions and water for interacting with the amide groups [55]. Salts also influence the insolubility of nonpolar groups in proteins, probably by modifying the structure of water. These effects are additive. 

The existence of interactions between amide groups and salt, and their correlation with optical activity were confirmed through the determination of association constants according to equilibrium (1) where Q, Cs and Cms the molar concentrations of model, salt and complex respectively ... 

When an appropriate salt [i.e. Ba(C104)2] is added, coordination takes place between the metal cations and the two carbonyl groups (amide/ester) at the... 

Barret and Hill have extensively studied the reactivity and catalytic activity of NHC-supported Group 2 amido complexes. Similar to several reports with the alkali metals, tricoordinate NHC-alkaline earth metal complexes 58 could be formed directly from the corresponding conjugate acid by addition of a metal amide salt (Scheme 5.8). Whereas carbene-Li complexes were found to be excellent carbene transfer reagents, 58 could function as a stable carbene equivalent. Indeed, in the presence of Lewis base donors such as triphenylphosphine oxide or protic substrates such as 2-methoxyethylamine, liberation of the free carbene was observed by and NMR. While the authors did not attempt to isolate this free carbene or investigate any additional reactivity, they claimed that the carbene was dissociated under catalyt-ically relevant conditions. 

Reaction with ammonia and amines (Section 20 14) Acid an hydrides react with ammonia and amines to form amides Two molar equivalents of amine are required In the example shown only one acyl group of acetic anhydride becomes incor porated into the amide the other becomes the acyl group of the amine salt of acetic acid... 

A significant fraction of the body s cholesterol is used to form bile acids Oxidation m the liver removes a portion of the CsHi7 side chain and additional hydroxyl groups are intro duced at various positions on the steroid nucleus Cholic acid is the most abundant of the bile acids In the form of certain amide derivatives called bile salts, of which sodium tau rocholate is one example bile acids act as emulsifying agents to aid the digestion of fats... 

The diacid-diamine amidation described in reaction 2 in Table 5.4 has been widely studied in the melt, in solution, and in the solid state. When equal amounts of two functional groups are present, both the rate laws and the molecular weight distributions are given by the treatment of the preceding sections. The stoichiometric balance between reactive groups is readily obtained by precipitating the 1 1 ammonium salt from ethanol ... 

The amide group is readily hydrolyzed to acrylic acid, and this reaction is kinetically faster in base than in acid solutions (5,32,33). However, hydrolysis of N-alkyl derivatives proceeds at slower rates. The presence of an electron-with-drawing group on nitrogen not only facilitates hydrolysis but also affects the polymerization behavior of these derivatives (34,35). With concentrated sulfuric acid, acrylamide forms acrylamide sulfate salt, the intermediate of the former sulfuric acid process for producing acrylamide commercially. Further reaction of the salt with alcohols produces acrylate esters (5). In strongly alkaline anhydrous solutions a potassium salt can be formed by reaction with potassium / /-butoxide in tert-huty alcohol at room temperature (36). 

Acylation. Acylation is the most rehable means of introducing a 3-substituent on the indole ring. Because 3-acyl substituents can be easily reduced to 3-aLkyl groups, a two-step acylation—reduction sequence is often an attractive alternative to direct 3-aLkylation. Several kinds of conditions have been employed for acylation. Very reactive acyl haUdes, such as oxalyl chloride, can effect substitution directiy without any catalyst. Normal acid chlorides are usually allowed to react with the magnesium (15) or 2inc (16) salts. The Vilsmeier-Haack conditions involving an amide and phosphoms oxychloride, in which a chloroiminium ion is the active electrophile, frequentiy give excellent yields of 3-acylindoles. 

Acetoiicetyliition Reactions. The best known and commercially most important reaction of diketene is the aceto acetylation of nucleophiles to give derivatives of acetoacetic acid (Fig. 2) (1,5,6). A wide variety of substances with acidic hydrogens can be acetoacetylated. This includes alcohols, amines, phenols, thiols, carboxyHc acids, amides, ureas, thioureas, urethanes, and sulfonamides. Where more than one functional group is present, ring closure often follows aceto acetylation, giving access to a variety of heterocycHc compounds. These reactions often require catalysts in the form of tertiary amines, acids, and mercury salts. Acetoacetate esters and acetoacetamides are the most important industrial intermediates prepared from diketene. 

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