Carboxyl derivatives bases

Rhodopsin is a seven ot-helix trans-membrane protein and visual pigment of the vertebrate rod photoreceptor cells that mediate dim light vision. In this photoreceptor, retinal is the chromophore bound by opsin protein, covalently linked to Lys296 by a Schiff base linkage. Kpega et al.64 have studied NMR spectra of Schiff bases being derivatives of all-frans retinal and amino-p-cyclodextrins as a model of rhodopsin, where p-cyclodextrin plays a role of a binding pocket. On the basis of analysis of the chemical shift differences for the model compound in the presence and in the absence of adamantane carboxylate, it has been shown that the derivative of 3-amino-p-cyclodextrin forms dimer in water and retinoid is inserted into p-cyclodextrin cavity [31]. 

Fu, L., Ferreira, R.A.S., Nobre, S.S., Carlos, L.D., and Rocha, J. (2006) Organically modified silica-based xerogels derived from 3-aminopropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane through carboxylic acid solvolysis. Mater. Sci. Forum 514-516, 108-112. 

Dunn and Bruice (1970, 1971) presented evidence that the mechanism of hydrolysis of methoxymethoxybenzoic acid is actually A-1. Evidence included a Bronsted coefficient for intramolecular catalysis of DO, based upon points for the unsubstituted compound and the 5-NO2 derivative, and p -values that were the same (—3-0) for both the methyl ester and the carboxyl derivatives of [72] when... 

An enolate anion generated from a carboxylic acid derivative may be used in the same sorts of nucleophilic reactions that we have seen with aldehyde and ketone systems. It should be noted, however, that the base used to generate the enolate anion must be chosen carefully. If sodium hydroxide were used, then hydrolysis of the carboxylic derivative to the acid (see Section 7.9.2) would compete with enolate anion formation. However, the problem is avoided by using the same base, e.g. ethoxide, as is present in the ester... 

Nucleophilic addition to C=0 (contd.) ammonia derivs., 219 base catalysis, 204, 207, 212, 216, 226 benzoin condensation, 231 bisulphite anion, 207, 213 Cannizzaro reaction, 216 carbanions, 221-234 Claisen ester condensation, 229 Claisen-Schmidt reaction, 226 conjugate, 200, 213 cyanide ion, 212 Dieckmann reaction, 230 electronic effects in, 205, 208, 226 electrons, 217 Grignard reagents, 221, 235 halide ion, 214 hydration, 207 hydride ion, 214 hydrogen bonding in, 204, 209 in carboxylic derivs., 236-244 intermediates in, 50, 219 intramolecular, 217, 232 irreversible, 215, 222 Knoevenagel reaction, 228 Lewis acids in, 204, 222 Meerwein-Ponndorf reaction, 215 MejSiCN, 213 nitroalkanes, 226 Perkin reaction, 227 pH and, 204, 208, 219 protection, 211... 

Carboxylic derivs., reaction, 230-244 acid hydrolysis, 240, base hydrolysis, 238 electronic effects in, 237 Grignard reagents, 238... 

Carboxylate derivatives of poly(vinyl alcohol) are biodegradable and function in detergents as cobuilders, although they are too cosdy to be practical as of 1996. Vinyloxyacetic acid has been polymerized (5) (101,102), and Lever has patented polymers, eg, poly(vinyloxyaspartic acid) (6), based on vinyl carbamates obtained from the reaction of vinjd chloroformates and amino acids such as aspartic and glutamic acids (103). Both hydrolyze to poly(vinyl alcohol) and then biodegrade. 

Some amino acids that behave as bases include arginine, lysine, histidine and the side chain carboxylates derived from glutamic and aspartic acid. Some amino acids that behave as acids include glutamic and aspartic acids, and the side chains conjugate acid of histidine (the imidazolium ion). 

The same group also showed that mono(cyclopentadienyl) mixed hydride/ aryloxide dimer complexes of several lanthanide elements (Y, Dy, Lu) could be synthesized easily by the acid-base reaction between the mixed hydride/alkyl complexes and an aryl alcohol [144]. These complexes reacted with C02 to generate mixed formate/carboxylate derivatives, which were moderately active initiators for the copolymerization of C02 and cyclohexene oxide, without requiring a co-catalyst. The lutetium derivative 21 was the most active (at 110°C, TOF = 9.4 h ), yet despite a good selectivity (99% carbonate linkages), the molecular weight distribution remained broad (6.15) (Table 6). 

The use of different acid functionalities on pyrrolidine-derived catalysts has improved the reaction rate of some aldol reactions. For example, pyrrolidine-based tetrazole derivative 9 (Fig. 2.2) catalyzed many aldol reactions with rates faster than proline, with similar stereocontrol [16, 18b, 24, 55]. The faster reaction rates with tetrazole derivative 9 in DM SO as compared with proline were attributed to the lower pKa of the tetrazole moiety as compared to the carboxylic acid group in DMSO (tetrazole pKa(DMSO) 8.2 acetic acid pKa(DMSO) 12.3) [55, 56]. In addition, tetrazole derivative 9 is more soluble than proline in many organic solvents. A higher actual concentration of the catalyst in the solution phase of a reaction mix-... 

The approach employed for the preparation of nortriquinacene derivatives was based upon ring contraction of the a-diazocarbonyl derivative and subsequent degradation of the epimeric carboxyl derivatives (Scheme 67).393 All attempts to deprotonate hydrocarbon 445 have proven unsuccessful. Metal reduction studies on 444 and the related chlorides also failed to provide evidence for formation of a stabilized carbanion. Calculations agree with the absence of significant homoconjugation in 429. For example, this species is predicted to have a pyramidal rather than a trigonal anionic carbon.393 In addition, exo-methylene derivatives of nortri-... 

The arrow pushing for the basic addition-elimination route for carboxyl derivatives follows. A very important crosscheck for this often-reversible route is the The reaction will tend to form the weaker base. If the leaving group is a lot less basic than the nucleophile, then the reaction may be irreversible (again the rule). 

Medium Acidic. Sources The lone pairs on the carbonyl are the best source (much better than the lone pairs of the OH). Leaving groups Chloride. Sinks The best, SOCI2, is a Y-L. The carboxylic acid is both an acid and a carboxyl derivative sink, but the OH is a poor leaving group. Acidic Hs The carboxylic acid s OH. Bases None. Resonance forms By VSEPR SOCI2 is tetrahedral, often drawn with an expanded octet resonance form containing a d-p pi bond. 

To further explore the question of the mechanism of anandamide amidase inhibition, analogs of anandamide were synthesized (Koutek et al. 1994). These anandamide analogs (figure 6) represent three classes of putative transition-state inhibitors trifluoromethyl ketone (4), -keto ester (3), and -keto amide derivatives (2). The general strategy of this study was based upon the h q)othesis that polarized carbonyls, such as those in trifluoromethyl ketones and -keto carboxylate derivatives, may form stabilized hydrates or enzyme adducts that mimic the tetrahedral... 

Tsiourvas D, Felekis T, Sideratou Z et al (2004) Ionic liquid crystals derived from the protonation of poly(propylene imine) dendrimers with a cholesterol-based carboxylic acid. Liq Cryst 31 739-744... 

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