Carboxylic hydrogenation

The rate of saponification of ethyl 2-thenoate, in contrast to ethyl 3-thenoate, was found to be considerably slower than predicted from the pKa of the acid, showing that the reactivities of thiophenes do not parallel those of benzene. The first explanation, that this was produced by a steric effect of the ring sulfur similar to the case in or /lo-substituted benzenes and in ethyl 1-naphthoate, could not be upheld when the same effect was found in ethyl 2-furoate. It was later ascribed to a stereospecific acid strengthening factor, involving the proper relation of the carboxylic hydrogen and the heteroatom, as the rate of saponification of 2-thienylacrylic acid was in agreement with that predicted from the acid constants. ... 

Carboxylic acids don t give addition products with Grignard reagents because the acidic carboxyl hydrogen reacts with the basic Grignard reagent to... 

The IR spectrum of carbene li indicates a very strong hydrogen bridge between the carboxyl hydrogen atom and the ring carbonyl group.92 The red shift... 

Since the phenomena occur just as well with the ester as with the free acid, the migrating hydrogen cannot be the carboxyl hydrogen. 

The esters name usually comes from the acid and ends in the suffix ate as does the word acetate itself. The acetate group is made from acetic acid by replacing the carboxyl hydrogen with an 7 group ... 

The allene VCD spectra can be interpreted in terms of the ring current mechanism (114). As shown in 46 and 47, for a conformation that maintains a planar orientation due to conjugation with the allene, for both the phenyl and carboxyl groups relative to the adjacent portion of the allene group, an intramolecular hydrogen bond is possible between the carboxyl hydrogen and a x orbital of the central allene carbon atom. The antisymmetric C=C=C stretch can be de-... 

As shown in Fig. 3, Lewis acids (i.e., metal ions and hydrogen bond donors) display syn or anti stereochemistry as they interact with the carboxylate anion. However, in a study of enzyme active sites. Candour (1981) first noticed that hydrogen bond donors to the carboxylates of aspartate and glutamate residues preferentially occur with syn stereochemistry. As a carboxylate-hydrogen bond donor interaction COg-H... 

As for carboxylate-hydrogen bond donor interactions, carboxylate-metal ion interactions are expected to be most favorable with syn stereochemistry. In a survey of the Cambridge Structural Database, Carrell et al. (1988) presented a stereochemical analysis of carboxylate—metal ion interactions which supports this expectation (Scheme 1). These investigators found that the syn-oriented lone electron pair of the carboxylate... 

Thus, it is the carboxylic hydrogen that is ultimately abstracted by this channel. This is consistent with the decrease in the room temperature rate constant upon deuterium substitution from 5.2 X 10 11 to 4.9 X 10 11 to 1.4 X 10 cm3 molecule-1 s for OH + CH3COOH vs OH + CD3COOH vs OH +... 

CD3COOD. Similarly, the rate constants for OH + HCOOH and DCOOH are identical (Wine et al., 1985). That is, only deuteration of the acidic hydrogen has a large effect on the rate constant. The acid dimer also reacts about two orders of magnitude slower than the monomer, because the carboxylic hydrogen is tied up in hydrogen bonding in the dimers ... 

Other additions, such as addition of alkyl halides and carbonyl compounds, are discussed in Chapter 5, whereas Chapter 7 covers addition reactions involving carbon monoxide (hydroformylation, carboxylations). Hydrogen addition is discussed in Chapter 11. The nucleophilic addition of organometallics to multiple bonds is of great significance in the anionic polymerization of alkenes and dienes and is treated in Chapter 13. 

The lactone formation occurs via a distorted five-membered transition state with participation of leaving chloride and carboxylic hydrogen. 

The use of isonicotinic acid ligands leads to a threefold interpenetrated neutral square grid network in which [Pt(L)2(HL)2] building blocks (L = isonicotinate) (cf. IX), resulting from deprotonation of half of the acid groups, are linked by carboxyl-carboxylate hydrogen bonds (Figure 18) [27c,57]. A network of the same... 

Figure 34 Cross-linking of Ni(p,-SCN)2L2 n coordination polymer via carboxyl-carboxyl hydrogen bonds between isonicotinic acid ligands (L) to give a sheet structure which stacks providing channels that can accommodate polycyclic aromatic hydrocarbon guest molecules, here anthracene [80], Oxygen, nitrogen and key hydrogen atoms are shaded nickel thiocyanate polymer and anthracene guest molecules shown in wireframe style.

Phenyl-2-saccharinylmethylene-3,5-dichloro-2(2-(4-morpholinyl)ethoxy)pyridine-4-carboxylate hydrogen chloride (Note 3)... 

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