Reduced forms

NADH is the reduced form of nicotinamide adenine dinucleotide. 

Panthenol (4) is the reduced form of pantothenic acid and is the pure form most commonly used. The alcohol is more easily absorbed and is converted iato the acid m vivo (12). Both panthenol and pantyl ether are used ia hair care products. 

In the example shown, the reduced form [49765-27-7] is blue with a visible absorption maximum at 610 nm. The rate of the reoxidation of the reduced form (cation radical, C24H22N" 2) is usually, but not always, strongly dependent on the presence of oxygen. 

In electro deposition, the reduced form of the metal is the elemental form M, x = 0, and there is no chelated M in solution. Neglecting activity coefficients, the reversible potential is 

All variables in the system can be expressed in reduced form. Velocity can be expressed as tt = where Uq is a fixed reference velocity and j/ is the dimensionless reduced velocity. Because time, /q, is the quotient of length, Lq, and velocity, Uq, the equation can be manipulated to yield 

The divalent cation methyl viologen is highly colored in reduced form and is used as an electrochromic in solution cells (Eig. 11). 

Furthermore, carehil carbonylation of the dimer produces [Cp 22 (CO)]2N which on protonolysis gives no reduced form of N2, iadicatiag that both bridging and terminal N2 are required for reduction (249). 

Transition point is at higher potential than the tabulated formal potential because the molar absorptivity of the reduced form is very much greater than that of the oxidized form. 

The Pictet-Gams method involves the cyclization of P-hydroxy- or P-methoxy- P-phenethylamides, and produces the isoquinoline derivative rather than the reduced form. A further extension of method is based on a metboxyetbyl amine. 

Figure 11.39 summarizes the reactions taking place in this amperometric sensor. FAD is the oxidized form of flavin adenine nucleotide (the active site of the enzyme glucose oxidase), and FAD1T2 is the active site s reduced form. Note that O2 serves as a mediator, carrying electrons to the electrode. Other mediators, such as Fe(CN)6 , can be used in place of O2. 

Before the equivalence point the titration mixture consists of appreciable quantities of both the oxidized and reduced forms of the analyte, but very little unreacted titrant. The potential, therefore, is best calculated using the Nernst equation for the analyte s half-reaction 

The most important class of redox indicators, however, are substances that do not participate in the redox titration, but whose oxidized and reduced forms differ in color. When added to a solution containing the analyte, the indicator imparts a color that depends on the solution s electrochemical potential. Since the indicator changes color in response to the electrochemical potential, and not to the presence or absence of a specific species, these compounds are called general redox indicators. 

Thus far the importance of carbon cluster chemistry has been in the discovery of new knowl edge Many scientists feel that the earliest industrial applications of the fullerenes will be based on their novel electrical properties Buckminsterfullerene is an insulator but has a high electron affinity and is a superconductor in its reduced form Nanotubes have aroused a great deal of interest for their electrical properties and as potential sources of carbon fibers of great strength 

Blends of polyester with cotton (qv) or viscose are first dyed with disperse dyes, then with sulfur dyes (see Fibers, polyester Fibers, regenerated CELLULOSics). Disperse and sulfur dyes can also be appHed simultaneously in a pad—dry—thermofix/chemical reduction pad—steam sequence. In this case, the sulfur dyes cannot be used in thein reduced form because of the effect of the sodium sulfide on the disperse dye. Therefore, this method is confined to the solubilized sulfur dyes or sulfur dyes in the dispersed form. 

In Table 8.26, E° represents the redox potential at which the color change of the indicator would normally be perceived in a solution containing approximately 1A7H+. Lor a one-color indicator this is the potential at which the concentration of the colored form is just large enough to impart a visible color to the solution and depends on the total concentration of indicator added to the solution. If it is the reduced form of the indicator that is colorless, the potential at which the first visible color 

Although EXo /ATcd is standard-state potential for the analyte s half-reaction, a matrix-dependent formal potential is used in its place. After the equivalence point, the potential is easiest to calculate using the Nernst equation for the titrant s half-reaction, since significant quantities of its oxidized and reduced forms are present. 

The first two terms of the right-hand side of the equation are sometimes combined and expressed as E which is called the standard oxidation potential for the chelate system. If the chelation is strong and the ligand is in excess, the metal would be almost entirely in the chelated forms, and [M L] and [M g L] would essentially be equal to the total concentrations of the oxidized and reduced forms of the metal. If, as is usual, the oxidized form is the more strongly chelated K > ), the oxidation potential of a system is increased by the addition of the chelant. 

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