Carboxylic acids amidation

A-/-Butyldimethylsilyl-7V-methyltrifluoroacetamide, CH3CN, 5 min, 97-100% yield.This reagent also silylates thiols, amines, amides, carboxylic acids, and enolizable carbonyl groups. 

Biochemical tests are usually performed after pure cultures have been obtained. The standard indole, methyl red, Voges-Proskauer, citrate, and litmus milk tests may be used to show important physiological characteristics. To study the functional diversity of bacteria, the utilization of carbohydrates, amines, amides, carboxylic acids, amino acids, polymers, and other carbon and nitrogen sources can be tested.28 Dilution-based most-probable number (MPN) techniques with phospholipid fatty acids as biomarkers have been employed for studying different bacterial species in lakes.40 The patterns of antibiotic resistance in bacteria isolated from natural waters have been useful for identifying sources of water pollution.34... 

A. T. Hagler, A. Lapicirella, Spatial Electron Distribution and Population Analysis of Amides, Carboxylic Acid, and Peptides, and Their Relation to Empirical Potential Functions , Biopolymers 1976, 1167-1200 A. T. Hagler, L. Leiserowitz, M. Tuval, Experimental and Theoretical Studies of the Barrier to Rotation about the N-C° and Ca-C Bonds ([Pg.369]

A question that may justifiably be raised here is whether these proofs of exclusive carbonyl protonation of carboxylic acids in concentrated and anhydrous acids necessarily imply the dominance of this form in dilute acid. Evidence that this is not so for amides has been discussed on pages 328 ff. It is possible that the alternative protonated form of carboxylic acids [201] is dominant in aqueous acid, but as the overall extents of protonation are small, it is not detectable by any spectroscopic method. Unlike amides, carboxylic acids become measurably protonated in quite concentrated acid (>60% sulphuric acid), which would tend to favour the formation of the protonated form with a delocalized charge. The form [201]... 

KETONES, ALDEHYDES, AMIDES, CARBOXYLIC ACIDS, AND ESTERS ALL CONTAIN A CARBONYL CROUP... 

The carbonyl group consists of a carbon atom double-bonded to an oxygen atom. It occurs in the organic compounds known as ketones, aldehydes, amides, carboxylic acids, and esters. 

The amide-carboxylic acid interaction forms one of the most studied supramolecular synthons. For example, the binary synthon formed by benzamide and benzoic acid arises by the hydrogen-bond interactions that cause the molecules to become linked into a dimeric species through O -- H-N and O-H O hydrogen bonds ... 

Alcohol, thiol, amine, amide, carboxylic acid, guanidine, and imidazole side chains are polar ... 

Saturated hydrocarbons < olefins < aromatic hydrocarbons = organic halides < sulfides < ethers < nitro compounds < esters = aldehydes = ketones < alcohols = amines < sulfones < amides < carboxylic acids... 

This latter thought has an important consequence if compounds with C=0 double bonds are sorted in decreasing order of resonance stabilization of their C=0 group they are at the same time sorted according to their increasing propensity to enolization. So as the resonance stabilization of the C=0 double bond decreases from 22 kcal/mol to somewhere near zero in the order carboxylic acid amide > carboxylic acid ester/carboxylic acid > ketone > aldehyde > carboxylic acid chloride/-bromide, the enol content increases in this same order (Figure 12.2). These circumstances immediately explain why no enol reactions whatsoever are known of carboxylic acid amides, virtually none of normal carboxylic acid esters/carboxylic acids, but are commonly encountered with ketones, aldehydes and carboxylic acid halides. 

Substituted derivatives of type (105) have been reported to undergo cleavage in the presence of acid to yield the acetic acid derivative (106 Scheme 48) (65AHC(5)119). The nitrile functions of the isomeric compounds (107) and (108) have been converted into the corresponding amides, carboxylic acids and methyl esters in the usual fashion (81JOC771). 

The mildness of the procedure provides the selective reduction of unsaturated carbonyl groups in the presence of almost any other functional groups such as ester, amide, carboxylic acid, nitro, halogen, nitrile, etc. It is evident that this reagent is far superior in purity and yield of products as compared to the conventional reagents, without any observable 1,4-reduction. 

For alkyl amines, a direct correlation between the steric bulk at the a-carbon and the yield of the reaction was found amines attached to a secondary carbon gave higher yields than amines connected to a tertiary carbon, while amines connected to a quaternary carbon led only to the formation of an amide-carboxylic acid intermediate, rather than the corresponding imide. In the case of amino acids whose ot-carbons are tertiary, a lower temperature was surprisingly required for high NMI selectivity in the first step (40 °C instead of 75 °C). This was explained by the presence of the COOR group, which assists in the collapse of the tetrahedral intermediate precursor to the imide formation. The amino acid derived NMIs were obtained as a mixture of open and closed forms due to the addition of triethylamine in the reaction. At high temperatures this promotes the formation of... 

Amides, Carboxylic acids can be converted directly into amides by reaction with this thiocyanate, tri-n-butylphosphine, and an amine in THF (20°, 7 hours). Yields are 95-100%. 

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