Carboxylic acids substitution

Fig. 4 The pseudorotaxane 10 of dibenzo[24]crown-8 and para-carboxylic acid substituted dibenzylammonium, linked to form a hydrogen bonded chain. Only hydrogen atoms involved in hydrogen bonding are shown [31]...

The loosening influence of the carboxyl group on adjacent hydrogen is much smaller. Hence, in carboxylic acids substitution by halogen proceeds with much more difficulty but can be accelerated by illumination and by catalysts (carriers). The point of entry of the halogen is here also always at the carbon atom adjacent to the carboxyl group, the a-carbon atom. 

At the present time quinuclidine 2-,90,118 3-,121 122 and 4-mono-carboxylic acids 97,100 are known as well as quinuclidine-2- carboxylic acids with various substituents at positions 395,108 or 5 99,110 and quinuclidine-3-carboxylic acids substituted at positions 2123 or 6.U1 Only one compound with two carboxylic groups in the quinuclidine ring, the 2,3-dicarboxylic acid, has been described.109 Homologs of many quinuclidinecarboxylic acids have been prepared, among which quinuclidine-3-acetic124-127 and 3-carboxymethylquinuclidine-2-carboxylic acids94 are interesting for subsequent transformations. 

The ortho- and para carboxylic acid substituted tetraphenyl porphyrins were used by Nishino and coworkers [36] to prepare the well defined 4-a-helix structures 42 and 43, which are soluble in lipid bilayer membranes. The rigid template of 42 provides some stability to the bundle structure (as measured by... 

Most alkanoic acids have values near 5, but the exact pK, of a given acid depends on structure. Carboxylic acids substituted by electron-withdrawing groups are more acidic (have a lower p/Cj) because their carbox) -ate ions are stabilized. Carboxylic acids substituted by electron-donating groups are less acidic (have a higher because their carboxylate ions are destabilized. 

At least two other routes of degradation in soil are apparent from the nature of the deg rad ate s formed. An initial propyl side chain oxidation of PBO leads to the formation of prop-1-one PBO. This then either undergoes carboxylic acid substitution at the 6-propyl position and hydroxylation to give 5 2-(2-bu toxy ethoxy) -e t hoxy- hy droxy me thy I ]- 6-c arboxy-1,3 -benzodiox ole, or 1 oss of the butoxy ethoxy ethoxy methyl side chain to form the corresponding prop-1-one benzaldehyde (Fig. 7.9). 

Miao and his coworkers developed an efficient and reusable catalytic system containing TEMPO functionalized imidazolium salt ([Imim-TEMPO]" X", Cat-la or Cat-lb), a carboxylic acid substituted imidazolium-based ionic liquid ([Imim-COOH]" X , Cat-2a or Cat-2b), and NaNO for the aerobic oxidation of alcohols with oxygen in water as solvent (Scheme 14.34) [31]. 

Both the chlorine and fluorine sulfonyl compounds strongly deshield the ortho aromatic hydrogens. The chemical shifts observed for the two phenyl compounds are extremely similar. A comparison of the para substituted compounds indicates identical shifts for the two para substituted methyl compounds, higher field shifts for the chlorine substituted sulfonyl fluoride but lower field shifts for the corresponding carboxylic acid substituted sulfonyl fluoride compared to the corresponding sulfonyl chlorides. 

The acidities of the two nitrogen protons of the pyrimidine ring are also the same, indicating that the dianions of both the 6- and 7-carboxylic acid-substituted lumazines are 1 1 mixtures of N1 and N3 deprotonated forms.256... 

Quinoxaline-2-carboxylic acids substituted in the 3-position have been widely prepared by reaction of an o-phenylenediamine with mesoxalic acid or its diethyl ester. Mesoxalic acid ester condensation proceeds as shown in Scheme 1. The resulting quinoxalinone carboxylate can be... 

N. Shibuya and R.S. Porter, Kinetics of PEEK sulfonation in concentrated sulfuric acid, Macromolecules, 1992, 25, 6495-6499 F. Wang and J. Rovers, Functionalization of poly(aryl ether ether ketone) (PEEK) Synthesis and properties of aldehyde and carboxylic acid substituted PEEK, Macromolecules, 1993, 26, 5295-5302. 

Only a few ketones have common names. The smallest ketone, propanone, is usually referred to by its common name, acetone. Acetone is a common laboratory solvent. Common names are also used for some phenyl-substituted ketones the number of carbons (other than those of the phenyl group) is indicated by the common name of the corresponding carboxylic acid, substituting ophenone for ic acid. ... 

Acrivastine, an acidic congener of triprolidine in which a carboxylic acid-substituted chain has been attached, also is a second-generation, nonsedating antihistamine. Penetration of the blood-brain barrier is limited, and it is less sedating than triprolidine. It is used principally in a combination with a decongestant. 

Carboxylic acid substituted quinolin-4-one derivatives constitute another class of biologically active compounds often known under the collective name quinolones . The development of quinolone antibacterials since the discovery of naphthyridine agent, nalidixic acid, has progressed with periods of great innovation. 

Anionic functional groups on the organic molecules circumvent the problems of a charged framework. Suslick and coworkers have explored the use of carboxylic acid-substituted porphyrins for building microporous porphyrinic... 

Isotope effects may be seen in equilibrium constants as well as in rate constants. The acidities of several carboxylic acids substituted with deuterium on the /3 carbon atom have equilibrium isotope effects, Ka(H)/ a(D) greater than 1.0 (Table 6.6). The simplest explanation of the data is that CD3 or CD2 groups are electron-releasing with respect to CH3 and CH2 groups. ... 

Triorganotin carboxylates tend to be monomers (.142 and 143) only with aromatic carboxylic acids (substituted benzoates) or with bulky substituents at tin (e.g. Ph or Cy) [420]. Most other organotin carboxylates are supramolecular aggregates, usually chain polymers with carboxylato bridging. 

The synthesis of carboxyl substituted polythiophenes has been investigated to a lesser degree in comparison with sulfonated polythiophenes. The self-doping in carboxyl substituted polythiophenes was first reported by Bauerle et al. [48]. They prepared a series of carboxylic acid substituted poly(3-alkylthienylenes). The monomers, 3-(m-carboxyalkyl)thiophenes, were prepared by reaction... 

Several groups have studied the synthesis of carboxylic acid derivatives of polypyrrole however, the electrochemistry of very few carboxylic acid substituted polypyrroles has been reported. Smith et al. [64] reported... 

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