88-44-8

Basic information

• Product Name: 4-Aminotoluene-3-sulfonic acid
• Synonyms: PTMS;PTMSA;P-TOLUIDINE-2-SULFONIC ACID;P-TOLUIDINE-M-SULFONIC ACID;6-AMINO-M-TOLUENESULFONIC ACID;4-AMINOTOLUENE-3-SULFONIC ACID;4B ACID;4-METHYLANILINE-2-SULFONIC ACID
• CAS NO: 88-44-8
• Molecular Formula: C₇H₉NO₃S
• Molecular Weight: 187.22
• EINECS: 201-831-3
• Product Categories: Intermediates of Dyes and Pigments;Intermediates;Organics
• Mol File: 88-44-8.mol
• Article Data: 17

Chemical Properties

• Melting Point: 300 °C
• Boiling Point: 500°C (rough estimate)
• Appearance: beige crystalline powder
• Density: 1.431
• Refractive Index: 1.6100 (estimate)
• Storage Temp.: Keep in dark place,Inert atmosphere,Room temperature
• Solubility: water: soluble6g/L at 20°C
• PKA: -1.35±0.42(Predicted)
• Water Solubility: 32g/L(19 oC)
• BRN: 2211509
• CAS DataBase Reference: 4-Aminotoluene-3-sulfonic acid(CAS DataBase Reference)
• NIST Chemistry Reference: 4-Aminotoluene-3-sulfonic acid(88-44-8)
• EPA Substance Registry System: 4-Aminotoluene-3-sulfonic acid(88-44-8)

Safety Data

• Hazard Codes: T,C,Xi
• Statements: 45-34-36
• Safety Statements: 53-26-27-28-36/37/39-45-28A
• RIDADR: UN 2585 8/PG 3
• WGK Germany: 2
• RTECS: XT6320000
• TSCA: Yes
• HazardClass: 8
• PackingGroup: III
• Hazardous Substances Data: 88-44-8(Hazardous Substances Data)

Usage

Chemical Properties

BEIGE CRYSTALLINE POWDER

Uses

4-Aminotoluene-3-sulfonic acid was used to investigate the enrichment of aminobenzoic acids and aminotoluenesulfonic acids using graphitized carbon black (GCB) by solid-phase extraction. It was also used in the synthesis of azobenzene derivatives.

General Description

4-Aminotoluene-3-sulfonic acid acts as Schiff base ligand and forms binary and ternary complexes with Co(II), Ni(II), Cu(II) and Zn(II) ions.

Flammability and Explosibility

Nonflammable

InChI:InChI=1/C7H9NO3S/c1-5-2-3-6(8)7(4-5)12(9,10)11/h2-4H,8H2,1H3,(H,9,10,11)/p-1

Synthetic route

6-methylbenzothiazole (2942-15-6) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With [RuCl(P(C6H5)3)2(O(C6H4)NCH(C4H3N))]; bromamine B; sodium hydroxide In water; acetonitrile at 39.84℃; for 4h;	96%

p-toluidine (106-49-0) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With sulfuric acid for 0.0416667h; microwave irradiation;	84%
With sulfuric acid at 170 - 180℃; for 3h;	70%
With sulfuric acid at 210 - 230℃;

4-toluidinium hydrogen sulfate (540-25-0) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
for 0.00833333h; microwave irradiation;	78%

1-methyl-4-nitrobenzene (99-99-0) → 4-methylphenylsulfamic acid (19063-15-1) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With sodium disulfite

4-amino-toluene-2-sulfonic acid (118-88-7) → 4-amino-toluene-3,5-disulfonic acid (68734-90-7) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With sulfuric acid at 180 - 200℃;

4-methyl-N-(4-methylphenyl)benzenesulfonamide (599-86-0) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With sulfuric acid

N-(4-methylphenyl)hydroxylamine (623-10-9) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With ethanol; sulfur dioxide

N,N-di-p-tolyl urea → 4-amino-toluene-2-sulfonic acid (118-88-7) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With sulfuric acid at 150 - 160℃;

4-(4-dimethylamino-phenylazo)-toluene-3-sulfonic acid → 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + 4-amino-N,N-dimethylaniline (99-98-9)

Conditions	Yield
durch Reduktion;

4-ureido-toluene-3-sulfonic acid (861519-01-9) + acetic anhydride (108-24-7) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

4-ureido-toluene-3-sulfonic acid (861519-01-9) + acetyl chloride (75-36-5) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 110℃; im Rohr;

4-ureido-toluene-3-sulfonic acid (861519-01-9) + aniline (62-53-3) → N,N-diphenylurea (603-54-3) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 160℃;

4-Methylacetanilide (103-89-9) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
With sulfuric acid at 140 - 170℃;

sodium p-methylphenylsulphamate (64808-23-7) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + p-toluidine (106-49-0)

Conditions	Yield
In methanol for 0.0166667h; Product distribution; Irradiation; var. solvents; var. radical scavangers;	A 41.2 % Chromat. B 54.1 % Chromat.

reactive red 45 (70210-46-7) + isopropyl alcohol (67-63-0) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + 3-Amino-5-[4-chloro-6-(methyl-phenyl-amino)-[1,3,5]triazin-2-ylamino]-4-hydroxy-naphthalene-2,7-disulfonic acid + acetone (67-64-1)

Conditions	Yield
In water Irradiation;

bis(4-toluidinium)sulfate (540-25-0, 24683-13-4, 68734-86-1) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 250℃; under 60 Torr; for 0.333333h;
at 250℃; under 60 Torr; for 0.333333h; Product distribution; Thermodynamic data; thermal decomposition; ΔH; activation energy; intermediates and reaction mechanism; cross sulfonation with α-naphthylamine;

6-methyl-1,1-dioxo-1,2-benzothiazol-3-one (4554-06-7) + alkaline potassium hypochlorite → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 80℃;

sulfuric acid (7664-93-9) + p-toluidine (106-49-0) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 210 - 230℃;
In thiophene

sulfuric acid (7664-93-9) + p-toluidine (106-49-0) → 4-amino-toluene-2-sulfonic acid (118-88-7) + 4-amino-toluene-3,5-disulfonic acid (68734-90-7) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 180℃; bis der Geruch nach schwefliger Saeure bemerkbar;

1-methyl-4-nitrosobenzene (623-11-0) + aqueous NaHSO3-solution → 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + p-toluidine (106-49-0)

1-methyl-4-nitrosobenzene (623-11-0) + Na2SO3-solution → 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + p-toluidine (106-49-0)

sulfuric acid (7664-93-9) + 4-methyl-N-(4-methylphenyl)benzenesulfonamide (599-86-0) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

4-amino-toluene-3,5-disulfonic acid (68734-90-7) → sulfuric acid (7664-93-9) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 200℃;

4-amino-toluene-3,5-disulfonic acid (68734-90-7) + water (7732-18-5) → sulfuric acid (7664-93-9) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

Conditions	Yield
at 140℃;

1-methyl-4-nitrobenzene (99-99-0) + disulfite solution → 4-methylphenylsulfamic acid (19063-15-1) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

p-toluidine (106-49-0) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + 4-amino-toluene-sulfonic acid-(2); 4-amino-toluene-disulfonic acid-(3.5)

Conditions	Yield
With sulfuric acid at 180℃;

methanol (67-56-1) + 4,4'-(4,8-dihydroxy-9,10-dioxo-9,10-dihydro-anthracene-1,5-diyl-di-amino)-bis-toluene-3-sulfonic acid (10449-13-5) + tin → 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + anthracenehexol-(1.4.5.8.9.10)

Conditions	Yield
Einleiten von Chlorwasserstoff;

ethanol (64-17-5) + N-(4-methylphenyl)hydroxylamine (623-10-9) + sulphurous acid (7782-99-2) → 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

hydrogenchloride (7647-01-0) + 4-(4-amino-3-bromo-9,10-dioxo-9,10-dihydro-[1]anthrylamino)-toluene-3-sulfonic acid (4988-32-3) + tin dichloride → 9,10-Dihydroxy-2,3-dihydro-anthracene-1,4-dione (17648-03-2) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8)

2-Amino-5-methylbenzenesulfonic acid (88-44-8) + 25,26,27,28-tetrakis(hydroxy)calix[4]arene (248590-47-8) → 5,11,17,23-tetrakis[(p-methyl-o-sulfophenyl)azo]-25,26,27,28-tetrahydroxycalix[4]arene

Conditions	Yield
Stage #1: 2-Amino-5-methylbenzenesulfonic acid With hydrogenchloride; sodium nitrite for 0.0333333h; Stage #2: 25,26,27,28-tetrakis(hydroxy)calix[4]arene With sodium carbonate In water for 0.0333333h; microwave irradiation; Further stages.;	92%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) + 1,4,5,8-naphthalenetetracarboxylic dianhydride (81-30-1) + naphthalene-1,8-diamine (479-27-6) → 5-methyl-2-(1,3,6-trioxo-3,6-dihydrobenzo-[lmn]-perimidino[2,1-b][3,8]phenanthroline-2(1H)-yl)-benzenesulfonic acid

Conditions	Yield
With 1H-imidazole at 170℃; for 3h;	83%

pyridine-2-carbaldehyde (1121-60-4) + copper(II) choride dihydrate + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) → C13H13ClCuN2O4S

Conditions	Yield
Stage #1: pyridine-2-carbaldehyde; 2-Amino-5-methylbenzenesulfonic acid In methanol; water at 60℃; for 1h; Stage #2: copper(II) choride dihydrate In methanol; water at 20℃; for 1h;	82%

pyridine-2-carbaldehyde (1121-60-4) + copper(II) choride dihydrate + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + water (7732-18-5) → C13H13ClCuN2O4S

Conditions	Yield
Stage #1: pyridine-2-carbaldehyde; 2-Amino-5-methylbenzenesulfonic acid; water at 60℃; for 1h; Stage #2: copper(II) choride dihydrate at 20℃; for 1h;	82%

formaldehyd (50-00-0) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 2-Dimethylamino-5-methyl-benzenesulfonic acid (203864-48-6)

Conditions	Yield
With hydrogen; palladium on activated charcoal In methanol; water under 2068.6 Torr;	78%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) + 1,4,5,8-naphthalenetetracarboxylic dianhydride (81-30-1) + 1,2-diamino-benzene (95-54-5) → 5-methyl-2-(1,3,6-trioxo-3,6-dihydrobenzimidazo[2,1-b]benzo[imn][3,8]-phenanthrolin-2-yl)benzenesulfonic acid

Conditions	Yield
With 1H-imidazole at 170℃; for 4h;	76%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) + copper diacetate (142-71-2) + 2-hydroxy-3-carboxy-1-naphtaldehyde (38399-46-1) → 2CO2C10H5(O)CHNHC6H3(SO3)CH3(2-)*2Cu(2+)*4H2O=(CO2C10H5(O)CHNHC6H3(SO3)CH3Cu(H2O)2)2

Conditions	Yield
With water In ethanol; water 2-hydroxy-3-carboxy-1-naphtaldehyde (0.001 mol) in warm EtOH was added to a soln. of 4-methyl-2-sulphonic acid aniline (0.001 mol) in hot water; the resulting orange soln. was cooled and filtered, the aq. soln. of Cu-compd. (0.001 mol) was added ;; the ppt. was filtered off, washed with water and dried over silica gel under vacuum; elem anal.;;	75%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) + (E)-3-ethoxyacrylaldehyde (764-63-6) → sodium 2-(3-oxo-1-propenylamino)-5-methylbenzenesulfonate (76889-71-9) + C17H16N2O6S2(2-)*2Na(1+)

Conditions	Yield
With sodium hydrogencarbonate In water Ambient temperature;	A 72.5% B n/a

2-Hydroxy-5-methylisophthalaldehyde (7310-95-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + zinc diacetate (557-34-6) → (N,N-(2-hydroxy-5-methyl-1,3-dibenzylidine)-bis-(4-methyl-2-sulphonate aniline))zinc*4.5hydrate

Conditions	Yield
With water In ethanol; water metal salt and 4-methyl 2-sulphonic acid aniline soln. in H2O filtered,stirred, soln. of 2-hydroxy 5-methyl isophthalaldehyde in EtOH added dropwise at room temp., stirred for 2 h; solid filtered off, washed with water, dried (vac.); elem. anal.;	71%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 2-amino-5-methylbenzenesulfonyl chloride

Conditions	Yield
With chlorosulfonic acid at 0 - 80℃; for 3h;	70%
With chlorosulphuric acid; sulfuric acid
With chlorosulphuric acid; sulfuric acid

2-Hydroxy-5-methylisophthalaldehyde (7310-95-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + copper diacetate (142-71-2) → (N,N-(2-hydroxy-5-methyl-1,3-dibenzylidine)-bis-(4-methyl-2-sulphonate aniline))copper*tetrahydrate

Conditions	Yield
With water In ethanol; water 4-methyl 2-sulphonic acid aniline in boiling water soln. mixed with 2-hydroxy 5-methyl isophthalaldehyde in hot EtOH soln., filtered hot, cooled to room temp., heated, soln. of Cu salt in H2O dropwise added with stirring; solid filtered, washed with H2O, dried (vac.); elem. anal.;	68%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) → Sodium 2-iodo-5-methylbenzenesulfonate

Conditions	Yield
Stage #1: 2-Amino-5-methylbenzenesulfonic acid With hydrogenchloride; sodium nitrite In water at 0 - 5℃; Stage #2: With sodium iodide In water at 0 - 50℃;	67%
With hydrogenchloride; urea; sodium iodide; sodium nitrite 1.) H2O, 0-5 deg C, 30 min, 2.) H2O, 0-5 deg C, 2 h; r.t., 1 h; 50 deg C, 13 h; Yield given. Multistep reaction;
Stage #1: 2-Amino-5-methylbenzenesulfonic acid With hydrogenchloride; sodium nitrite Stage #2: With potassium iodide Further stages.;

2-Hydroxy-5-methylisophthalaldehyde (7310-95-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + magnesium acetate (142-72-3, 92123-19-8) → (N,N-(2-hydroxy-5-methyl-1,3-dibenzylidine)-bis-(4-methyl-2-sulphonate aniline))magnesium*4.5H2O

Conditions	Yield
In water metal salt and 4-methyl 2-sulphonic acid aniline hot soln. filtered, stirred at 60°C, hot soln. of 2-hydroxy 5-methyl isophthalaldehyde dropwise added; cooled, filtered, standed overnight at 5°C, crystals filtered off, washed with water, then with acetone, dried (vac.); elem. anal.;	62%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 2-Iodo-5-methylbenzenesulfonic acid (139778-27-1)

Conditions	Yield
Stage #1: 2-Amino-5-methylbenzenesulfonic acid With sodium carbonate In water Stage #2: With sodium nitrite In water at 0℃; for 0.75h; Further stages;	56%
Multi-step reaction with 2 steps 1: 1.) NaNO2, conc. HCl, 2.) NaI, urea / 1.) H2O, 0-5 deg C, 30 min, 2.) H2O, 0-5 deg C, 2 h; r.t., 1 h; 50 deg C, 13 h 2: 65 percent / aq. HCl / r.t., 3 h; 50 deg C, 2 h; r.t., overnight View Scheme
Stage #1: 2-Amino-5-methylbenzenesulfonic acid With sodium carbonate; sodium nitrite In water at 0℃; for 0.5h; Stage #2: With hydrogenchloride In water for 0.5h; Cooling with ice; Stage #3: With potassium iodide In water at 0 - 80℃;

2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 4-Methyl-7-thia-8-aza-bicyclo[4.2.0]octa-1(6),2,4-triene 7,7-dioxide

Conditions	Yield
With phosphorus pentachloride In trichlorophosphate	55%

2-Hydroxy-5-methylisophthalaldehyde (7310-95-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + manganese(II) acetate (638-38-0, 993-02-2, 2180-18-9, 15411-95-7, 22981-23-3, 27004-39-3) → (N,N-(2-hydroxy-5-methyl-1,3-dibenzylidine)-bis-(4-methyl-2-sulphonate aniline))manganese*1.5hydrate*di-acetic acid

Conditions	Yield
In water metal salt and 4-methyl 2-sulphonic acid aniline hot soln. filtered, stirred at 60°C, hot soln. of 2-hydroxy 5-methyl isophthalaldehyde dropwise added; cooled, filtered, standed overnight at 5°C, crystals filtered off, washed with water, then with acetone, dried (vac.); elem. anal.;	53%

2-Hydroxy-5-methylisophthalaldehyde (7310-95-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + nickel diacetate (373-02-4, 14998-37-9, 33025-09-1, 94044-50-5, 98268-31-6) → (N,N-(2-hydroxy-5-methyl-1,3-dibenzylidine)-bis-(4-methyl-2-sulphonate aniline))nickel*4.5hydrate

Conditions	Yield
With water In ethanol; water metal salt and 4-methyl 2-sulphonic acid aniline soln. in H2O filtered,stirred, soln. of 2-hydroxy 5-methyl isophthalaldehyde in EtOH added dropwise at room temp., stirred for 2 h; solid filtered off, washed with water, dried (vac.), recrystd. (water);elem. anal.;	50%

2-Hydroxy-5-methylisophthalaldehyde (7310-95-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + cobalt(II) acetate (71-48-7, 917-69-1, 5931-89-5, 55881-15-7, 68931-68-0, 68931-69-1, 93029-27-7) → (N,N-(2-hydroxy-5-methyl-1,3-dibenzylidine)-bis-(4-methyl-2-sulphonate aniline))cobalt*4.5hydrate

Conditions	Yield
With water In ethanol; water metal salt and 4-methyl 2-sulphonic acid aniline soln. in water filtered, stirred, soln. of 2-hydroxy 5-methyl isophthalaldehyde in EtOH added dropwise at room temp., stirred for 2 h; solid filtered off, washed with water, dried (vac.); elem. anal.;	50%

pyridine-2-carbaldehyde (1121-60-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + water (7732-18-5) + copper(II) bis(trifluoromethanesulfonate) (34946-82-2) → C26H22Cu2N4O6S2(2+)*2CF3O3S(1-)

Conditions	Yield
Stage #1: pyridine-2-carbaldehyde; 2-Amino-5-methylbenzenesulfonic acid; water In methanol at 60℃; for 1h; Stage #2: copper(II) bis(trifluoromethanesulfonate) In methanol for 1h;	40%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 4,4'-azotoluene-3,3'-disulfonic acid

Conditions	Yield
With sodium perborate hexahydrate; boric acid; acetic acid at 60℃; for 6h;	35%

2-Hydroxy-5-methylisophthalaldehyde (7310-95-4) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) + iron(II) sulfate → (N,N-(2-hydroxy-5-methyl-1,3-dibenzylidine)-bis-(4-methyl-2-sulphonate aniline))iron*1.5hydrate*di-acetic acid

Conditions	Yield
With water; sodium acetate In water (N2); metal salts and 4-methyl 2-sulphonic acid aniline hot soln. filtered, stirred at 60°C, hot soln. of 2-hydroxy 5-methyl isophthalaldehyde dropwise added; cooled, filtered, standed overnight at 5°C, crystals filtered off, washed with water, then with acetone, dried (vac.); elem. anal.;	30%

2-Amino-5-methylbenzenesulfonic acid (88-44-8) + (bromomethyl)pentafluorobenzene (1765-40-8) → potassium 2-(2,3,4,5,6-pentafluorobenzylamino)-5-methylphenyl sulfonate

Conditions	Yield
With potassium carbonate In N,N-dimethyl-formamide at 20℃; for 12h;	24%

potassium cyanate (590-28-3) + 2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 4-ureido-toluene-3-sulfonic acid (861519-01-9)

Conditions	Yield
With hydrogenchloride

2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 2,6-dinitro-p-cresol (609-93-8)

Conditions	Yield
Diazotization.Erhitzen der Diazoniumverbindung mit verd. Salpetersaeure;
With nitrogen oxides; water

2-Amino-5-methylbenzenesulfonic acid (88-44-8) → 2,6-Dibromo-4-methylaniline (6968-24-7)

Conditions	Yield
With water; bromine

Upstream product

• 99-99-0 1-methyl-4-nitrobenzene 
• 118-88-7 4-amino-toluene-2-sulfonic acid 
• 106-49-0 p-toluidine 
• 103-89-9 4-Methylacetanilide 
• 70210-46-7 reactive red 45 
• 67-63-0 isopropyl alcohol 
• 540-25-0 bis(4-toluidinium)sulfate 
• 4554-06-7 6-methyl-1,1-dioxo-1,2-benzothiazol-3-one 
• 7664-93-9 sulfuric acid 
• 623-11-0 1-methyl-4-nitrosobenzene 
• 599-86-0 4-methyl-N-(4-methylphenyl)benzenesulfonamide 
• 68734-90-7 4-amino-toluene-3,5-disulfonic acid 
• 7732-18-5 water 
• 67-56-1 methanol 

Downstream Products

• 116436-09-0 4-acetylamino-toluene-3-sulfonyl chloride 
• 203864-48-6 2-Dimethylamino-5-methyl-benzenesulfonic acid 
• 24061-09-4 5-methyl-2-diazobenzenesulphonic acid 
• 7664-93-9 sulfuric acid 
• 106-49-0 p-toluidine 
• 99-96-7 4-hydroxy-benzoic acid 
• 6968-24-7 2,6-Dibromo-4-methylaniline 
• 583-68-6 2-bromo-p-toluidine 
• 56919-22-3 4-bromo-toluene-3-sulfonic acid 

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The sulfonation of aromatic amines with high yields, simple operations and short reaction time has been studied under microwave irradiation in solvent-free conditions.

Sulfonation of arylamines: Part III - Solid state synthesis of 2-amino-5-methylbenzenesulfonic acid

p-Ditoluidinium sulfate (p-DTS) has been obtained from p-toluidine on treatment with conc. H2SO4 and characterized by molecular weight determination, elemental, gravimetric and spectral analyses. p-DTS yields 2-amino-5-methylbenzenesulfonic acid via solid state reaction induced by heat. A suitable reaction mechanism has been proposed.