What is Red Dye 33 Made of and Is It Safe?

Red dye 33, also known as D&C Red No. 33 or CI 17200, is a synthetic azo dye derived from petroleum or coal tar sources. Its vibrant red hue is used to color a wide variety of personal care and pharmaceutical products globally. Unlike the banned Red Dye 3, Red 33 has a different regulatory history and chemical structure.

Quick Summary

Red Dye 33 is a synthetic azo dye produced from petroleum. The coloring agent, known chemically as the disodium salt of 5-amino-4-hydroxy-3-(phenylazo)-2,7-naphthalenedisulfonic acid, is used in cosmetics and drugs.

Key Points

• Synthetic Origin: Red Dye 33 is a synthetic azo dye produced from petroleum or coal tar, not from animals or plants.

• Chemical Makeup: It is the disodium salt of 5-amino-4-hydroxy-3-(phenylazo)-2,7-naphthalenedisulfonic acid, with the chemical formula $$C{16}H{11}N_3Na_2O_7S_2$$.

• Manufacturing Process: It is made by coupling diazotized aniline with H-acid in an alkaline solution.

• Cosmetic and Drug Use: The dye is widely used in cosmetics like lipstick, hair dyes, and mouthwashes, as well as in specific pharmaceuticals.

• Regulatory Distinction: Red Dye 33 is not Red Dye 3; it has different regulations and is approved for use in drugs and cosmetics under FDA and EU rules.

• Forms: It can exist as a water-soluble dye or as a water-insoluble "lake" pigment, depending on its application.

The Chemical Composition of Red Dye 33

Red Dye 33 is a synthetic organic compound with the chemical name disodium salt of 5-amino-4-hydroxy-3-(phenylazo)-2,7-naphthalenedisulfonic acid. It is classified as an azo dye due to the presence of the azo chemical group ($$ -N=N- $$) in its structure, which imparts its red color. The dye has a complex chemical formula of $$ C{16}H{11}N_3Na_2O_7S_2 $$. Its naphthalenedisulfonic acid component originates from petroleum or coal tar, distinguishing it from natural colorants.

The Synthetic Manufacturing Process

Red Dye 33 is artificially created through a chemical process, rather than being extracted from natural sources. This synthesis involves a coupling reaction carried out in an alkaline aqueous medium.

Key components involved in the synthesis are:

• Aniline: A petroleum-derived, toxic, colorless organic compound.
• 5-amino-4-hydroxy-2,7-naphthalenedisulfonic acid (H-acid): An intermediate used in producing azo dyes.

Overview of the Coupling Reaction:

1. Aniline undergoes diazotization using nitrous acid.
2. The resulting intermediate is coupled with H-acid in an alkaline solution.
3. The final product, a dark reddish-brown powder, is isolated and purified.

This method ensures consistent color and stability for use in various products.

Forms and Applications of Red Dye 33

Red Dye 33 comes in a water-soluble form and a water-insoluble "lake" form, each suited for different applications.

Products potentially containing Red Dye 33 include:

• Mouthwashes and dentifrices
• Lipsticks and lip glosses
• Shampoos and conditioners
• Hair dyes
• Certain skin care products
• Some pharmaceuticals

Regulations and Safety Profile

In the U.S., D&C Red No. 33 is regulated by the FDA under Title 21 of the Code of Federal Regulations. It is important to differentiate Red Dye 33 from Red Dye 3, which has faced bans. The FDA certifies batches of Red Dye 33, setting limits on impurities. It is allowed in cosmetics and externally applied drugs as per good manufacturing practices, and in ingested drugs up to 0.75 mg daily. The European Union also regulates it in cosmetics under the name CI 17200.

Red Dye 33 vs. Natural Colorants

The following table compares the synthetic Red Dye 33 with beetroot extract, a natural red colorant.

Feature	Red Dye 33 (CI 17200)	Beetroot Extract
Origin	Synthetic, from petroleum or coal tar.	Natural, from beets.
Composition	Azo dye.	Betalain pigments.
Stability	Highly stable.	Sensitive to heat, light, pH.
Color Intensity	Vivid, intense red/purple.	Rich, less intense red.
Taste/Odor	Typically none.	Can be earthy.
Regulatory Status	FDA-certified for drugs/cosmetics.	GRAS for food.
Application	Cosmetics, mouthwashes, pharmaceuticals.	Food, beverage, some cosmetics.

Conclusion: Understanding a Common Synthetic Colorant

Red Dye 33 is a synthetic azo dye derived from petroleum, with a defined chemical structure and manufacturing process. It is distinct from Red Dye 3 and is regulated by authorities like the FDA for use in cosmetics and pharmaceuticals. Its stability and vibrant color make it useful in various products. Consumers can identify it by looking for "D&C Red No. 33" or "CI 17200" on labels. Understanding its nature and regulation helps in making informed product choices. More regulatory details are available in the Electronic Code of Federal Regulations.

What are some examples of products containing Red Dye 33?

• Shampoos, conditioners, and hair dyes.
• Lipsticks and lip glosses.
• Certain mouthwashes and toothpastes.
• Specific externally applied drugs.
• Some liquid hand washes and body washes.

Is Red Dye 33 derived from animals?

No, Red Dye 33 is a synthetic dye produced from petroleum or coal tar and is not animal-derived.

Frequently Asked Questions

Is Red Dye 33 the same as Red Dye 3?

No, Red Dye 33 (D&C Red No. 33) is not the same as Red Dye 3 (Erythrosine). They are different chemical compounds with distinct safety and regulatory histories.

Is Red Dye 33 approved for use in food?

While Red Dye 3 was banned for use in food, Red Dye 33 is primarily approved for use in certain cosmetics, externally applied drugs, and ingested drugs with a dose limitation.

How can I tell if a product contains Red Dye 33?

You can identify Red Dye 33 by checking the product's ingredient list for "D&C Red No. 33" or its international color index name, "CI 17200".

Is Red Dye 33 safe?

Regulatory bodies like the FDA have evaluated Red Dye 33 and approved it for specific uses in cosmetics and drugs, subject to strict manufacturing standards and purity specifications.

What is the source of Red Dye 33?

Red Dye 33 is a synthetic compound derived from petroleum or coal tar sources and is not sourced from natural materials.

What is a "lake" form of Red Dye 33?

A "lake" is the water-insoluble form of the dye, which is created by reacting the dye with a metallic salt. This makes it suitable for products that lack sufficient moisture to dissolve a water-soluble dye.

Are there natural alternatives to Red Dye 33?

Yes, natural alternatives for red coloring include beetroot extract, anthocyanins from berries or red cabbage, and carmine from cochineal insects.