Compounding defined

The term nootropic has been used to describe a class of compounds defined by the abibty of its members to facibtate learning (36). The compounds are most effective in animals that have had their cognitive abihties compromised in some way. The molecular mechanism undedying the cognitive-enhancing... 

The replacement of the endocyclic oxygen of the sugar with a nitrogen atom generates a class of compounds defined imino sugars. 

Mineral A naturally occurring element or compound defined by its chemical composition and crystal structure (see chapter 2). By custom in recent times, mineral species have been given names ending in ite. Each year, about 100 new species are proposed, and usually about half are accepted by the International Mineralogical Association Commission on New Names as bona fide new species. The Glossary of Mineral Species (Fleischer, 1987) is a current source of information. Updates are published annually in the Mineralogical Record. 

The reasons for these choices are as follows. For most practical purposes a compound of a reasonably high degree of enantiomeric purity is the desired goal of an enantiosclcctivc reaction. The most convenient way to achieve this result is by recrystallization of the product or a derivative. This process, in the majority of cases, involves separation of the pure enantiomer from the racemate. The ee value, being equivalent to the percentage of the major isomer in the mixture with the racemic compound, defines the maximum yield of the pure isomer that can... 

Figure 3.6 Plot of the natural logarithms of the partition constants at 25°C of a series of apolar, monopolar, and bipolar organic compounds between air and (a) n-hexadecane (n-C H34) and (b) water versus the dispersive vdW- parameter of the compounds defined by Eq. 3-10. Note that from Eq. 3-10 only the compound part is used because the solvent part (1) is the same for all compounds, and that TSA, is in cm2 mol-1.

How is the Kioc (KlV0C) value of a given compound defined How large is the variability of Kioc (KiT)0C) for (a) different particulate organic phases (POM), and (b) different dissolved organic phases (DOM) Which are the major structural factors of POM or DOM that cause this variability ... 

How is the decadic molar extinction coefficient, ,(/l), of a given compound defined What is described by the decadic light absorption or light attenuation coefficient,... 

How is the first-order direct photolysis rate constant of a given compound defined What is(are) the prerequisite(s) that direct photolysis can be expressed by a first-order rate law ... 

COX-1 and COX-2 have virtually identical tertiary and quaternary structures, but they differ subtly in a long, thin hydrophobic channel extending from the membrane interior to the lumenal surface. The channel includes both catalytic sites and is presumed to be the binding site for the hydrophobic substrate, arachidonate. Both COX-1 and COX-2 have been crystallized in the presence of several different bound NSAID compounds, defining the NSAID-binding site (Fig. 1). The bound drugs block the hydrophobic channel and prevent arachidonate entry The subtle differences between the channels of COX-1 and COX-2 have guided... 

H2S04H20, is produced, accompanied by higher hydrated compounds defined by the formula H2S04 xH20. Likewise nitric acid is capable of forming hydrates. Thus in the nitrating mixture an equilibrium corresponding to the eqn. (1) is postulated ... 

Since phenol is benzene with a hydroxyl group, the reactivity of phenol and phenolic compounds is in many ways dictated by the chemical properties of the benzene ring. The first property to consider is acidity. A compound is considered an acid when it can release a proton (H ) while in solution. The acid constant Ka of a compound defines to what extent the proton is released. Strong acids will completely dissociate, whereas weak acids (HA) are at equilibrium with their dissociated state ... 

After Cram had discovered the selectivities now named after him, he proposed the transition state model for the formation of Cram chelate products that is still valid today. However, his explanation for the preferred formation of Cram products was different from current views. Cram assumed that the transition state for the addition of nucleophiles to a-alkylated carbonyl compounds was so early that he could model it with the carbonyl compound alone. His reasoning was that the preferred conformation of the free a-chiral carbonyl compound defines two sterically differently encumbered half-spaces on both sides of the plane of the C=0 double bond. The nucleophile was believed to approach from the less hindered half-space. 

Plant phenolics represent a very large group of defensive compounds defined here as having a phenol (hydroxybenzene) moiety. In some instances substances having a phenolic precursor (e.g. methoxybenzene derivatives) have conveniently also been included in this category. Phenolics derive biosynthetically from hydroxycinnamoyl coenzyme A (yielding a phenyl-propanoid moiety). 

Figure 13.11 Principle of PCA-based library design. The original data space X is spiked with a virtual optimum (denoted by a star in a) whereas in b) a set of reference compounds defines the optimum), thereby defining a target area for compound selection. After PCA, the relevant principal components (PC) span an orthogonal space, and distance criteria are used for picking compounds that are closest to the a) virtual optimum, or b) reference compounds.

Ionization efficiency of a compound defines the conversion of a neutral molecule to a charged particle (ion). It directly affects the detection limit and sensitivity of a mass spectrometer in LC/MS system. There are several instrumental parameters that play important roles in the ionization efficiency of a compound. These parameters (and their names) are usually vendor-specific. 

Chemistry of Functional Groups, ed. S. Patai, Z. Rappoport, and others, Wiley, 1964- An extensive multivolume series. Each volume covers all aspects of a particular class of compound defined by functional group. Recent volumes are now available online and the titles of the complete series are at http //eu.wiley.com and http //www3.interscience.wiley.com. 

Standard-grade, commercial lecithin from the soybean is a complex mixture. It comprises phospholipids, triglycerides, and minor amounts of other constituents (i.e., phytoglycolipids, phytosterols, tocopherols, and fatty acids). The composition and molecular arrangement of this heterogeneous mixture of compounds defines a product that is low in apparent polarity and has a strong tendency to promote water-in-oil (w/o)-type emulsions (31). 

The heat of reaction may be rewritten in terms of the partial molar enthalpies of the compounds defined by... 

A linear relationship has been demonstrated by Clayden and Pugh (1998) between the quadrupole coupling constant Xq and the ionic radius r (in nm) of the M ions in the small group of sodium metal(IV) phosphates NaM2(P04)3 where M = Sn, Ge, Ti and Zr. The two resolvable Na sites of NaSn2(P04)3 straddle the line for these compounds, defined by ... 

The most useful thermochemical data are tables of the standard enthalpy of formation AH° for compounds, defined as the enthalpy of formation of a compound in its standard state from the elements in their standard states at 1 atm and 298.15K. 

The novel purified compound anandamide seems to be present as brain constituent. It is possible that this compound is present as a complex with another compound or in any other form, but according to the present invention it has been established that the compound defined herein as ananamide is characterized by the properties set out herein. Similar compounds, defined herein, are characterized by essentially equivalent properties. 

---