Y-acid

Preparation. The general preparation of y acids is by the hydrolysis of an a-halo acid or by the acid hydrolysis of the cyanohydrins of an aldehyde or a ketone. 

The zeoHtes used for catalysis are principally modified forms of zeoHte Y, acid forms of synthetic mordenite, and ZSM-5. 

An example of an a2o dyestuff in which y-acid is the coupling component is Acid Red 337 (19), which is obtained through the reaction of dia2oti2ed -trifluoromethylaniline and y-acid (52). 

With nitious acid the hydio y-acid ib foimed,... 

The hydiobiomides of /3-y unsaturated acids like /S-phenyl-crotonic acid beha e Cjuite differently. On l oiling with water, lactones are formed, i.e., inner anhydrides of o. y-acids,... 

In many cases estimating the impact of acid deposition on various ecosystems can be a difficult process because acid deposition is only one of many impacts that can effect a response. However, wet and di y acid deposition has been documented as a major factor in the following ecosystem responses. 

Interesting regioselectivities have been known for more than 100 years for azo coupling reactions with aminonaphthol derivatives such as 6-amino-4-hydroxy-2-naphthalenesulfonic acid (12.136, y-acid), 7-amino-4-hydroxy-2-naphthalenesulf-onic acid (J-acid), and 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (H-acid). They give two types of isomeric azo compounds depending on the pH-value of the... 

In this contribution, we describe and illustrate the latest generalizations and developments[1]-[3] of a theory of recent formulation[4]-[6] for the study of chemical reactions in solution. This theory combines the powerful interpretive framework of Valence Bond (VB) theory [7] — so well known to chemists — with a dielectric continuum description of the solvent. The latter includes the quantization of the solvent electronic polarization[5, 6] and also accounts for nonequilibrium solvation effects. Compared to earlier, related efforts[4]-[6], [8]-[10], the theory [l]-[3] includes the boundary conditions on the solute cavity in a fashion related to that of Tomasi[ll] for equilibrium problems, and can be applied to reaction systems which require more than two VB states for their description, namely bimolecular Sjy2 reactions ],[8](b),[12],[13] X + RY XR + Y, acid ionizations[8](a),[14] HA +B —> A + HB+, and Menschutkin reactions[7](b), among other reactions. Compared to the various reaction field theories in use[ll],[15]-[21] (some of which are discussed in the present volume), the theory is distinguished by its quantization of the solvent electronic polarization (which in general leads to deviations from a Self-consistent limiting behavior), the inclusion of nonequilibrium solvation — so important for chemical reactions, and the VB perspective. Further historical perspective and discussion of connections to other work may be found in Ref.[l],... 

Of far greater importance are the sulphonated aminonaphthols, in which the versatility conferred by the presence of both an amino and a hydroxy group makes them among the most important group of azo intermediates. Three are outstanding, namely, 6-amino-l-naphthol-3-sulphonic acid (4.16 J acid), 7-amino-l-naphthol-3-sulphonic acid (4-17 y acid) and H acid (4.2), which couple under the relevant conditions of pH at the arrowed positions. 

In orange dyes of the haloheterocyclic type, the reactive system is invariably attached via the nitrogen of the ] acid coupler. In vinylsulphone dyes, on the other hand, it is normally more convenient to use as diazo component an intermediate such as 7.38 or 7.39 bearing the precursor grouping together with an N-acetylated derivative of ] acid or y acid as coupler, structure 7.93 being typical. 

Dyes in this hue sector are also derived from ] acid, N-methyl ] acid or y acid but the diazo component is usually a sulphonated 2- or 4-anisidine, as a methoxy substituent has a bathochromic influence. The highly substantive structure 7.94 is found in various haloheterocyclic (Z) dyes. As in the orange region, vinylsulphone dyes have the precursor grouping located on the diazo arylamine, as exemplified by structure 7.95. 

PERCHLORYL COMPOUNDS PEROXOACID SALTS PEROXOACIDS PEROX Y ACIDS... 

A particularly important class of coupling components are the aminohydroxy-naphthalenesulfonic acids. Appropriate variation of the disazo component permits the development of shades ranging from orange to black. Orange and scarlet are achieved with I-acid (6-amino-l-hydroxy-naphthalene-3-sulfonic acid) and y-acid (7-amino-1-hydroxynaphthaIcne-3-sulfonic acid), whereas H-acid (8-amino-l-hydroxynaphthalene-3,6-disulfonic acid) and K-acid (8-amino-l-hydroxy-naphthalene-3,5-disulfonic acid) derivatives are useful for red to bluish-red hues. Extremely lightfast red shades are also accessible with disazo dyes ( brown dyes ). For chemical structures see Section 3.1.5). 

C. I. Direct Black 51, 27720 [3442-21-5] (13) is produced by coupling a mixture of diazotized 3- and 5-aminosalicylic acid to 1-naphthylamine and subsequent alkaline coupling to y acid. 

C. I. Direct Black 150, 32010 [6897-38-7] (15), is produced by double (alkaline) coupling of bis-diazotized 4,4 -diaminodiphenylamine-2-sulfonic acid to y acid and subsequent single coupling to m -phenylenediamine. 

Anilinesulfonic acids are chiefly used as starting component D, naphthylamine and Cleve acids as middle components Mi and M2, and I acid, its /V-phenyl derivatives, H acid, 2-amino-8-hydroxynaphthalene-6-sulfonic acid (y acid), and their derivatives as final component K. This type mainly possesses blue and green shades. Example C. I. DirectBlue 78, 34200 (16) [2503-73-3],... 

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