Functional groups, organic carboxylic acid

This hydrogen bonding capacity expressed by the polar selectivity is not limited to an increase in retention for phenols. Packings with embedded polar groups that excel in this feature also exhibit increased retention for analytes with other functional groups. Specifically, carboxylic acids at acidic pH and with acetonitrile as the organic modifier and compounds with sulfonamide functions at acidic and neutral pH exhibit significant... 

Organs and tissues in the body can have very different pHs. The pH of blood is 7.4. The stomach can be as low as 1, while the small intestine is slightly basic at about 8. Functional groups, especially carboxylic acids, can lose or gain a charge as they move from one part of the body to another. If the solution pH and pKa of the acid are known, then the relative concentrations of the acid and its conjugate base can be calculated through the Henderson-Hasselbalch equation (Equation 9.1). 

The reactions to produce volatile derivatives can be classified as silylation, acylation, alkylation, and coordination complexation. Examples of the first three types are included in Table 10.1 which is organized by functional groups including carboxylic acid, hydroxyl, amine, and carbonyl. Amines require special consideration even if they are volatile. Their strong tendency to hydrogen-bond often makes it difficult to elute them from a GC column. Consequently, amines often have to be derivatized whether they are volatile or not. A review of this subject has appeared recently [29]. 

In addition to the three major families of compati-biUzation reactions outlined above, organic polymer chemists have applied their ingenuity to a great variety of other reactions which can be used to compatibilize polyolefin polyblends. These may be classified as reactions of certain functional groups epoxy, carboxylic acid, hydroxyl, amine, oxazoline, and miscellaneous others. 

An alpha hydroxy acid is an organic carboxylic acid in which an additional hydroxyl functional group (-OH) is present at the alpha position, i.e., on the carbon adjacent to the carboxyl functionality, -COOH. Figure 13.10.1 presents the struc-... 

The presence of acidic functional groups, mostly carboxyl and phenolic OH groups, in the molecular structure of soil HS renders them major players in the acid-base buffering capacity of soils and in the fate, bioavailability, and physico-chemical behavior of macro- and micronutrients, toxic metal ions, and several xenobiotic organic compounds in soil (Ritchie and Perdue, 2003 Senesi and Loffredo, 2005). Consequently, the effects of amendment on the acid-base properties of soil HAs and FAs is a subject of considerable interest. 

Classification and Organization of Reactions Forming Difunctional Compounds. This chapter considers all possible difunctional compounds formed from the groups acetylene, carboxylic acid, alcohol, thiol, aldehyde, amide, amine, ester, ether, epoxide, thioether, halide, ketone, nitrile, and olefin. Reactions that form difunctional compounds are classified into sections on the basis of the two functional groups of the product. The relative positions... 

Dihydrooxazoles continue to occupy an important place in organic synthesis and medicinal chemistry as they have found use as versatile synthetic intermediates, protecting groups/pro-drugs for carboxylic acids, and chiral auxiliaries in asymmetric synthesis. There are several protocols in the literature for the transformations of functional groups such as acids, esters, nitriles, hydroxyl amides, aldehydes, and alkenes to 2-oxazolines. Newer additions to these methods feature greater ease of synthesis and milder conditions. 

All amino acids share two chemically functional groups, the carboxyl group and the amino group. Thus, they will share the chemical reactions of these groups familiar from organic chemistry. Many of these reactions are exploited in the laboratory manipulation of amino acids, peptides, and proteins. Note that these reactions are also common to the side chains of asp, glu (-COOH), and lys (-NH2). Another side-chain with important chemistry is cys (-SH). Biologically the most important reactions are those required for protein formation, particularly the peptide bond. 

Assigning the peaks to individual carbons in a C SSNMR experiment is not always trivial, as peaks can vary by more than 10 ppm from their solution values. In a broad sense, peaks from 160 to 180 ppm are due to carbonyl groups of carboxylic acid derivatives, 200-220 ppm are due to ketone carbonyls, 100-160 ppm are from aromatic and olefinic carbons, 50-100 ppm are from sp -hydridized carbons attached to heteroatoms, and 10-40 ppm are typically aliphatic carbons attached to other carbons and/or hydrogens. These are purely estimates of the basic functionalities found in most organic molecules, and exceptions to these ranges are not uncommon. Many crystalline systems also possess more than one crystallographically inequivalent molecule per unit cell, which is also easily detectable in SSNMR experiments and can make interpretation of spectra more complicated. For instance, if two peaks exist in the C SSNMR spectrum for each carbon, there are two molecules in the unit cell, although not every peak in each inequivalent molecule is always resolved. 

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