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Beta Naphthol Orange Synthesis Essay

Apparatus and Reagents

Cyclic voltammetry, controlled-potential coulometry and preparative electrolysis were performed using an Autolab model PGSTAT 30 and a Behpazho potentiostat/galvanostat. The working and counter electrode used in macro-scale electrolysis and coulometry was an assembly of four ordinary soft carbon rods (6 mm diameter and 4 cm length). Working electrode used in the cyclic voltammetry experiments was a glassy carbon disc (1.8 mm diameter) and a platinum rod was used as a counter electrode. The electrosynthesis were performed under constant-current condition in an undivided cell. The glassy carbon electrode was polished using alumina slurry (from Iran Alumina Co.). More details are described in our previous paper47. Acid orange 7, arylsulfinic acids and phosphate salts were obtained from commercial sources. These chemicals were used without further purification.

Electroorganic Synthesis of 3a–3c

An aqueous phosphate buffer solution (70 ml, c = 0.2 M, pH 2.0) containing AO7 (0.25 mmol) and arylsulfinic acid (1a–1c) (0.25 mmol) was electrolyzed in an undivided cell under constant current conditions (current density = 0.32 mA cm−2) for 2 h 45 min. At the end of electrolysis, the cell was placed in a refrigerator overnight. The precipitated solid was collected by filtration and washed several times with water. After recrystallization in ethyl ether, the products were characterized by IR, 1H NMR, 13C NMR and mass spectroscopy.

1-Amino-3-tosylnaphthalen-2-ol (C17H15NO3S) (3a)

mp: 163–164 °C; isolated yield 65%. 1H NMR (400 MHz, DMSO-d6): δ = 2.32 (s, 3 H, methyl), 6.22 (s, ~1 H, NH, this peak disappeared upon addition of D2O), 7.36 (m, 4 H, J = 8 Hz, aromatic), 7.71 (d, 2 H, J = 8.4, aromatic), 8.04 (s, 1 H, aromatic), 8.11 (m, 1 H, aromatic), 8.29 (m, 1 H, aromatic), 9.86 (s, ~1 H, OH, this peak disappeared upon addition of D2O); 13C NMR (100 MHz, DMSO-d6): δ = 21.3, 119.5, 120.5, 122.7, 123.1, 123.9, 124.8, 125.0, 125.8, 126.9, 130.2, 136.7, 137.7, 140.4, 143.7; IR (KBr): 3384, 2926, 1704, 1622, 1354, 1266, 1200, 1140, 1083, 951, 755, 668, 571, 529 cm−1; MS (EI, 70 eV): m/z (relative intensity %): 313 (M+, 31), 270 (6), 158 (100), 139 (11), 130 (65), 91 (24), 77 (15), 65(18).

1-amino-3-(phenylsulfonyl)naphthalen-2-ol (C16H13NO3S) (3b)

mp: 209–210 °C; isolated yield 60%. 1H NMR (400 MHz, DMSO-d6): δ = 6.27 (s, ~1 H, NH, this peak disappeared upon addition of D2O), 7.38 (dd, 2 H, J = 3.2 and 10.0 Hz, aromatic), 7.57 (m, 3 H, aromatic), 7.85 (dd, 2 H, J = 2.0 and 6.8 Hz, aromatic), 8.09 (s, 1 H, aromatic), 8.18 (dd, 1 H, J = 3.2 and 10.0 Hz, aromatic), 8.33 (dd, 1 H, J = 3.2 and 10.0 Hz, aromatic), 9.91 (s, ~1 H, OH, this peak disappeared upon addition of D2O); 13C NMR (100 MHz, DMSO-d6): δ = 118.8, 120.7, 122.7, 123.2, 123.9, 124.7, 125.1, 125.8, 126.8, 129.8, 133.1, 136.8, 138.2, 143.4; IR (KBr): 3473, 3379, 3073, 3025, 1739, 1616, 1358, 1286, 1207, 1136, 1082, 952, 784, 740, 557 cm−1; MS (EI, 70 eV): m/z (relative intensity %): 299 (M+, 21), 257 (7), 160 (16), 159 (55), 158 (100), 130 (58), 103 (16), 77(44), 51(24), 43 (74).

1-amino-3-((4-chlorophenyl)sulfonyl)naphthalen-2-ol (C16H12ClNO3S) (3c)

mp: 164–165 °C; isolated yield 62%. 1H NMR (400 MHz, DMSO-d6): δ = 6.33 (s, ~1 H, NH, this peak disappeared upon addition of D2O), 7.38 (dd, 2 H, J = 3.2 and 9.6 Hz, aromatic), 7.62 (d, 2 H, J = 8.8 Hz, aromatic), 7.85 (d, 2 H, J = 8.8 Hz, aromatic), 8.06 (d, 1 H, J = 2.8 Hz, aromatic), 8.19 (m, 1 H, aromatic), 8.28 (m, 1 H, aromatic), 9.92 (s, ~1 H, OH, this peak disappeared upon addition of D2O); 13C NMR (100 MHz, DMSO-d6): δ = 118.2, 120.6, 122.6, 123.1, 123.7, 124.3, 124.9, 125.0, 126.2, 128.8, 129.9, 136.7, 138.2, 142.0; IR (KBr): 3362, 3286, 3068, 1630, 1309, 1284, 1174, 1144, 1085, 906, 824, 781, 752, 648, 580 cm−1; MS (EI, 70 eV): m/z (relative intensity %): 333 (M+, 24), 174 (12), 158 (100), 130 (58), 111 (21), 103 (18), 77 (17), 75 (28), 50 (18).

An azo coupling is an organic reaction between a diazonium compound and another aromatic compound that produces an azo compound. In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the electrophile and the activatedarene is a nucleophile.[1] In most cases, including the examples below, the diazonium compound is also aromatic.

Diazotization[edit]

The process of conversion of primary aromatic amines into its diazonium salt is called diazotization. Diazonium salts are important synthetic intermediates that can undergo coupling reactions to form azo dyes and electrophilic substitution reactions to introduce functional groups.

Uses of the reaction[edit]

The product will absorb longer wavelengths of light (specifically they absorb in the visible region) than the reactants because of increased conjugation. Consequently, aromatic azo compounds tend to be brightly colored due to the extended conjugated systems. Many are used as dyes (see azo dye).[2] Important azo dyes include methyl red and pigment red 170.

Azo coupling is also used to produce prontosil and other sulfa drugs.

Examples of coupling reactions[edit]

Many procedures have been described.[3][4]Phenol reacts with benzenediazonium chloride to give a yellow-orange azo compound. The reaction is base-catalysed.[2]

The related dye called aniline yellow is produced from the reaction of aniline and the diazonium salt.[2]

Naphthols are popular acceptors. One example is the synthesis of the dye "organol brown" from aniline and 1-naphthol:

Similarly β-naphthol couples with phenyldiazoniumelectrophile to produce an intense orange-red dye.

References[edit]

  1. ^Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, ISBN 0-471-72091-7 
  2. ^ abcKlaus Hunger; Peter Mischke; Wolfgang Rieper; Roderich Raue; Klaus Kunde; Aloys Engel (2005). "Azo Dyes". Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_245. .
  3. ^J. L. Hartwell and Louis F. Fieser. "Coupling of o-tolidine and Chicago acid". Organic Syntheses. ; Collective Volume, 2, p. 145 
  4. ^H. T. Clarke and W. R. Kirner. "Methyl red". Organic Syntheses. ; Collective Volume, 1, p. 374 

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