Caiboxylic groups

Substitution of caiboxylic groups by halogen via Ag saHs (Hunsdiecker, Borodin) or Hg salts (Cnstol-Rrth)... 

Caiboxylate groups are hydrophilic ( water-loving ) and tend to confer water solubility on species that contain them. Long hydrocarbon chains are lipophilic ( fat-loving ) and tend to associate with other hydrocarbon chains. Sodium stearate is an exfflnple of an amphiphilic substance both hydrophilic and lipophilic groups occur within the sfflne molecule. 

Notice that the caiboxyl group that stays behind during the decarboxylation of malonic acid has a hydroxyl function that is not directly involved in the process. Compounds that have substituents other than hydroxyl groups at this position undergo an analogous decarboxylation. 

By agreement, peptide structures aie written so that the ffluino group (as H3N— or H2N—) is at the left and the caiboxyl group (as CO2 or COiFl) is at the right. The... 

The amino acids used for the covalent coupling are types with functional side chains e.g. Cys, Lys, Tyr and Asp, comprising thiol, amino, phenohc and caiboxylic groups. The reactivity of these residues will be determined by the chosen coupling chemistry and its conditions, where Lys and the N-terminal amino group are the most frequently used amino acids for covalent attachment. 

One important group of condensation polymers is the polyesters. The most important commercial polyester is formed from the reaction of terephthalic acid (a diacid) with ethylene glycol (a diol). This polymerization occurs in a stepwise fashion (hence the name step growth polymerization). First, one carboxylic acid group of a diacid molecule and one hydroxy group of a diol molecule combine to form an ester, with the loss of water. Then a second diol molecule reacts with the unreacted caiboxylic group on the other end of the diacid molecule, or a second diacid molecule reacts with the unreacted hydroxy group of the diol. Continuation of this process adds a new monomer unit at... 

Table 7-17. Relative Rates of Initamolecular Catalysis of Ester Hydrolysis by Caiboxylate Groups...

When a substance such as sodium chloride is dissolved in water, the ions that form become completely surrounded by water molecules, which form structures called hydration spheres. When the sodium salt of a fatty acid is mixed with water, the caiboxylate group of the molecule becomes hydrated but the hydrophobic hydrocarbon portion of the molecule is poorly hydrated, if at all. The hydrocarbon chains from numerous fatty acids tend to clump together in spherical structures called micelles or, if large numbers are present, into bilayer sheets. Using a circle to represent the carboxylate group and an attached squiggly line to represent the hydrocarbon chain of a fatty acid, draw a picture of a micelle and a bilayer. 

The caiboxyl group of the sialic acid interacts with three arginine residues, Arg 115, Arg 291 and Arg 373. The acetyl group fits neatly into a hydrophobic pocket formed by Trp 176, lie 220 and the aliphatic parts of Arg 149 and Arg 222, with an additional hydrogen bond of the carbonyl oxygen to Arg 149. 

The role of the caiboxylate group is rendered more pronrmnced wiien its electrostatic contribution is augmented by hj rophobic forces. Kunitake and Shinkai examined the catalytic activity of copolymers containing the phenylimidazoIe(PI) unit and acrylate (or methacrylate) units 39 85). 

Fig. 1.4 Atomic force microscope images of immunosensor platforms a SWCNT forest on silicon b SWCNT forest coated with chemically attached antibodies c a PDDA/gold nanoparticle (AuNP) bilayer on smooth mica d phase contrast image of the same PDDA/ AuNP bilayer e anti-PSA antibodies attached onto caiboxylate groups of the AuNP/PDDA bilayer.Reproduced with permission from reference 68 (a, b), copyright Royal Society of Chemistry, 2005, and reference 46 (c-a), copyright American Chemical Society 2009.

Figure 10. Scheme for the synthesis of well-defined polymers carrying sodium caiboxylate groups. 

Scheme 3.10 Chiral variants for alkylation of carbanion a to the caiboxylic group...

This proton only shows J couplings. Hb is ortho to a caiboxyl group while He is ortho to a nitro group. Both protons are deshielded, but the nitro group shifts a proton further downfield than for... 

In an attempt to demonstrate this effect, the trinuclear complex described in the previous section has been modified so as to have caiboxylate groups in the 4,4 positions of the bipytidine ligands of the central unit [24]. The NC-Rufbpyjj-CN-RuEfCOOjj-bpyJj-NC-Rufbpyjj-CN complex is schematically depicted in Fig 8. The photophysical behavior of this complex is almost... 

Ex. 3 Verona (Bayer) supplies Impranil 4496 (DLN) color stable, 40% solids, thermoplastic, aliphatic poly (ester-urethane), anionic, aqueous dispersion. Samples have appeared to contain a trace of solvent (acetone, MEK ). Presumably Impranil 4496 (DLN) contains a polyurethane ionomer and is prepared without added emulsifier, the polyurethane itself having its own emulsifier function. The incorporation of this function in the polyurethane chains as sodium (A) sulfonate or (B) caiboxylate groups is seen in the following equations " ... 

The inhibitor molecules bond to the metal substrate through the functional organic moiety (the caiboxylate group in the case of steel and the phosphate group in case of aluminium alloys) forming a bimetallic complex with the metal. 

Fig. 1.23 Representation of the complexes between the caiboxylate group of the inhibitor and the ionic groups of the recognition site of FAK together with the discrete waters. Reprinted with permission from de Courcy et al. J. Am. Chem. Soc. 2010, 132, 3312. Copyright 2010 American Chemical Society...

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