Vernier Software and Technology
Vernier Software & Technology

Synthesis of Methyl Orange and Its Application to Textiles


The practice of using dyes is perhaps the most ancient art of chemistry. Dyeing substances from plant, animal, or mineral sources has been known before written history. The accidental discovery of the purple dye, mauve, by W.H. Perkin in 1856 is generally considered to be the birth of the modern chemical industry. Several other synthetic dyes followed. One important group is known as the azo dyes, which are named after their unusual N=N, azo, functional group.

In this experiment, you will synthesize methyl orange from sulfanilic acid and N,N-dimethylaniline using a diazonium coupling reaction, a common reaction for treating an aliphatic amine to yield a carbocation. The reaction between a primary aliphatic amine and nitrous acid gives an unstable diazonium salt that loses N2 to give a carbocation. The carbocation may then either (1) lose a proton to give an alkene, (2) react with a nucleophile, or (3) rearrange, followed by (1) or (2). The nucleophile we are using here is dimethylaniline. Attack is in the para position due to steric hindrance at the ortho position by the bulky dimethylamine substituent. Because you are synthesizing an azo dye, your product purity will easily be determined using a Spectrophotometer.


In this experiment, you will

  • Synthesize methyl orange from the reaction of a primary amine with nitrous acid.
  • Calculate your product purity using a Spectrophotometer.
  • Observe the spectroscopic changes of methyl orange under acidic and basic conditions.
  • Explore how organic chemistry is an essential component of the textile industry.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Option 1

Option 2

Option 3

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Organic Chemistry with Vernier

See other experiments from the lab book.

1Determining Melting Temperature
3Determination of a Boiling Point
4Identifying an Unknown Analgesic by Three Methods
5Separation of Organic Compounds by Acid-Base Extraction Techniques
6Understanding Polarimetry
7Identification of Organic Unknowns Using Polarimetry
8Investigating Gas Chromatography
9Fractional Distillation of Esters
10Understanding Intermolecular Forces Using a Gas Chromatograph: Enthalpy of Vaporization
11Investigating Thermodynamic Relationships of Substituted Hydrocarbons
12Extraction of Spinach Pigments and Analysis by Electronic Absorption Spectroscopy
13SN1: Synthesis of t-butyl chloride
14SN2: Synthesis of 1-bromobutane
15Observing the Reaction Kinetics of Sucrose with Polarimetry
16The Synthesis and Analysis of Aspirin
17Isolation of R-(+)-Limonene from Oranges using Steam Distillation
18Synthesizing Ethyl Acetate by Fisher Esterification
19Synthesis of Dibenzalacetone by Aldol Condensation
20The Diels-Alder Reaction of Anthracene with Maleic Anhydride
21Friedel-Crafts Acylation of Ferrocene
22Grignard Formation of Crystal Violet
23Synthesis of Fluorescein
24Synthesis of Methyl Orange and Its Application to Textiles
25Analysis of Natural Products
26Using a Gas Chromatograph: Identifying an Unknown Compound

Experiment 24 from Organic Chemistry with Vernier Lab Book

<i>Organic Chemistry with Vernier</i> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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