Naphthalene, acylation sulfonation

Such reactions are normally base catalyzed. Scheme 76 illustrates the use of this reaction to provide both fused and bridged rings. Other techniques for synthesizing the keto ester from trimethylsilyl ethers are shown in Scheme 77. The diketones shown were usually isolated as a mixture of enols or enol ethers. Acid-catalyzed acylation also provides a route to diketones not readily obtained by other routes (Scheme 78). The acid catalysts included polyphosphoric acid and naphthalene-2-sulfonic acid. In the latter example continuous removal of water facilitated the reaction. A related reaction involved treatment of an acid chloride with silver perchlorate in nitromethane (equation 41), although the yield of diketone was low. ° ... 

Anthraquinone dyes are derived from several key compounds called dye intermediates, and the methods for preparing these key intermediates can be divided into two types (/) introduction of substituent(s) onto the anthraquinone nucleus, and (2) synthesis of an anthraquinone nucleus having the desired substituents, starting from benzene or naphthalene derivatives (nucleus synthesis). The principal reactions ate nitration and sulfonation, which are very important ia preparing a-substituted anthraquiaones by electrophilic substitution. Nucleus synthesis is important for the production of P-substituted anthraquiaones such as 2-methylanthraquiQone and 2-chloroanthraquiaone. Friedel-Crafts acylation usiag aluminum chloride is appHed for this purpose. Synthesis of quinizatia (1,4-dihydroxyanthraquiQone) is also important. 

In addition to oxidation and reduction reactions, naphthalene readily undergoes substitution reactions such as nitration, halogenation, sulfonation, and acylation to produce a variety of other substances, which are used in the manufacture of dyes, insecticides, organic solvents, and synthetic resins. The principal use of naphthalene is for the production of phthalic anhydride, CgbLO,. 

We have seen that naphthalene undergoes nitration and halogenation chiefly at the a-position, and sulfonation and Friedel-Crafts acylation at either the a- or jS-position, depending upon conditions. Now, to what position will a second substituent attach itself, and how is the orientation influenced by the group already present ... 

Aryl amine intermediates for azo and triphenylmethane dyes, as well as a number of vat dye (anthraquinone) intermediates, are made from compounds such as benzene, alkyl benzenes (toluene and higher homologues), phenol and naphthalene. A limited number of reactions are used to produce the most important dye intermediates, including nitration, reduction, halogenation, sulfonation, /V-alkylation, /V-acylation and alkali fusion33,34. 

When SO3 itself is employed, the concentration is at a maximum and the initial stage of the sulfonation is completed easily and rapidly. However, the sulfonic acid formed in the initial stage easily reacts with a second mole of SO3 to form a complex which may be much less reactive than SO3 itself. Thus, when reacting a hydrocarbon with SO3 on an equimolar basis, one half of the hydrocarbon is sulfonated with SO3 and the other half is sulfonated by the less reactive complex (see the section on Kinetics). Likewise, when sulfonating organic acids with SO3, the initial reaction product is an acyl sulfate which is next converted to the desired sulfonate under considerably more drastic conditions. The second half of these reactions is the slower, and the rate and reaction conditions are determined by the stability of the initial complex, which varies greatly. The benzene-sulfonic acid-S03 complex is quite reactive, while that from naphthalene-disulfonic acid is comparatively unreactive. When SO3 is used for sulfation, the reaction appears simpler ... 

Similarly, l-anilinonaphthalene-8-sulfonic acid (ANS) only emits in a hydrophobic environment, being almost completely quenched in aqueous solution. ANS and some other dyes, including 6-(p-toluidinyl)naphthalene-2-sulfo-nate, pyrene, l,6-diphenyl-l,3,5-hexatriene, fluorescein, and rhodamine derivatives attached to long acyl chains or to fatty acids that localize in the cellular membranes were used as probes for hydrophobic sites in proteins, protein folding, imaging of membranes of the cell, and solvent polarity. Pyrene-labeled fatty acids were used to detect the fusion of two membranes. When present in a membrane at sufficiently high concentrations, pyrene excimers (excited-state dimers) are formed that emit at 470 nm. Upon fusion with other membranes, probe concentration decreases, and excimer fluorescence is replaced by monomer fluorescence at 400 nm. This process can be monitored by ratiometric detection of pyrene labels. 

Anti-HIV agents N-acyl amino-naphthalene sulfonic acid derivatives... 

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