Is galaxolide biodegradable? (3 categories of musks)

This article shall address the question of the biodegradability of galaxolide.

It shall also address other areas such as:

  • Properties of galaxolide.
  • Applications of galaxolide.
  • Classes of synthetic musks.
  • Eco-friendliness of galaxolide.

Is galaxolide biodegradable?

No, galaxolide is a synthetic musk that is made from the galaxolide chemical. The galaxolide chemical is not susceptible to bacterial and fungal enzymatic degradation.

Biodegradation is highly dependent on the types of substances and their chemical properties. Some chemicals such as galaxolide can not be acted upon by the microorganisms because they (microorganisms) do not have the machinery to break them ( chemicals).

What is biodegradation?

Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi into the water, carbon dioxide, methane, and minerals. Heat energy is produced in the process.

Biodegradation occurs in three distinct stages: biodeterioration, bio-fragmentation, and assimilation.

Biodeterioration is the first stage of biodegradation that involves abiotic factors such as light, UV radiation, and water to help in the weakening of the structure of organic substances.

Bio-fragmentation is the second stage that involves the physical breakdown of organic matter into small particles, this is due to the biodeterioration of the organic matter in the first stage.

Assimilation is the last stage of biodegradation. It involves the bacteria and the fungi taking up the minerals and small biomass produced by the previous two stages into their biological systems.

The minerals are used as a source of energy and carbon for the synthesis of cells and tissues.

Biodegradation can occur in the presence or absence of oxygen. When biodegradation involves the microorganisms using oxygen, the process is called aerobic biodegradation.

Aerobic biodegradation produces carbon dioxide, water, and small biomass. Heat energy is also produced in the process. Aerobic biodegradation occurs very fast but it is not very efficient.

When biodegradation occurs in the absence of oxygen, it is called anaerobic biodegradation. The products of anaerobic biodegradation include water, carbon dioxide, and small biomass. In addition to these products, methane gas is also produced. Heat energy is released during the breakdown. 

Anaerobic biodegradation occurs slowly but is more efficient than aerobic biodegradation.

Biodegradation can be affected by several factors such as water, light, temperatures, the bioavailability of a molecule, and pH.

Water helps in the biodeterioration and mechanical fragmentation of substances, increasing the surface area for microbial degradation.

Light emits radiations that help in the biodeterioration and bio-fragmentation of organic matter. UV radiation is the most effective radiation. 

Temperature affects the rate of biodegradation. Some microorganisms are very active in high temperatures while others are active in low temperatures. The optimum temperatures for the microorganisms increase the rate of biodegradation.

Bioavailability is the availability of an organic substance to microorganisms. Highly concentrated organic matter has high bioavailability and this increases the rate of biodegradation.

pH is the measure of acidity or basicity of a substance. Some microorganisms are very active in acidic pH while others are active in neutral or alkaline pH. Optimum pH increases the rate of biodegradation.

What is musk?

Musk is a class of aromatic compounds that are usually used in perfumes. Musks can be naturally secreted by animals such as musk deer, numerous plants, and synthetic substances that emit similar fragrances to those emitted by plants and animals.

The name ‘musk’ was derived from a substance with a strong odor that was obtained from a gland of the musk deer. The substance has long been used as a perfume fixative.

The chemical behind the strong odor of the substance derived from the musk gland is muscone.

Muscone: This is an organic compound that consists of 15-membered ketone with a methyl substitution in the 3-position. 

Muscone is an oily liquid. It is an enantiomer of 3-methyl cyclopentadecanone. The liquid is slightly soluble in water and is miscible with alcohol.

Muscone is naturally produced by glands of the musk deer, as a result, there have been concerns over the killing of the already endangered animal, this has led to the synthesis of artificial muscone.

Apart from the musk deers, substances with musk-like odors can also be obtained from other animals such as:

  • Muskrat.
  • Musk duck.
  • Muskox.
  • Musk shrew.
  • Musk beetle.
  • African civet.
  • Musk turtle.
  • American alligator.
  • Lynx musk.
  • Crocodiles.

Some plant species also produce musk-like odor-producing compounds. These compounds are widely used to make perfumery. 

The compounds can be produced by the musk flower, the musk wood, and the musk seeds.

What are the classes of musks?

Musks can be categorized based on their sources or chemical components. The two main classes include; natural musks and synthetic musks.

Natural musks.

Natural musk is naturally produced by plants and animals. As earlier mentioned, the very first musk odor was produced by the glands of the musk deer.

The substance produced by the gland contains a musky odor because of the presence of the muscone aromatic compound.

Apart from the musk deer, other animals also produce musky odors, such animals include crocodiles, American alligators, musk beetle, musk shrew, musloy, muskat, and the musk turtle.

Some plants also produce musk odors. Such plants include musk wood, musk seeds, and musk flower.

Synthetic musks.

Due to the rising concerns about the safety of the musk deers, synthetic musks have gained popularity in recent years. These musks are also called white musks.

Synthetic musks have the following properties:

  • They have a sweet, clean, and smooth scent.
  • They are synthesized to emulate the odors of muscone and civetone compounds.

Synthetic musks are further divided into:

  • Aromatic nitro musks.
  • Polycyclic musks compounds.
  • Macrocyclic musk compounds.

Aromatic nitro musks.

These are musks produced by condensing toluene chemicals with isobutyl bromide in the presence of aluminum chloride. 

The compound formed is then nitrated by reacting it with a nitrate-based compound.

The most common type of aromatic nitro musk is musk xylene. This compound was once the most widely used chemical in fragrances but has since declined in its usage due to concerns about its explosiveness and carcinogenicity. 

Polycyclic musks.

These musks are made from compounds such as octahedron-tetramethyl naphthofuranone and galaxolide.

Galaxolide.

Galaxolide is a synthetic musk with a clean, musky floral wood smell. It is used as a fragrance fixative.

Galaxolide is a common ingredient in perfumes and other compounds such as detergents and fabric plasticizers.

It is a highly viscous liquid at room temperature. It melts at -20⁰ Celsius and boils at 330⁰ Celsius.

Macrocyclic musks.

Macrocyclic musks are made from macrocyclic lactone compounds and macrocyclic ketone compounds.

Macrocyclic lactone musks.

These musks are made from macrocyclic lactones. They include the following:

  • Cyclopentadecanolide, exaltolide, and pentalide from 15-pentadecanolide lactone.
  • Habanolide and globalide from oxacyclohexadec-12/13-en-2-one lactone 
  • Musk R 1 from 12-oxa-16-hexadecanolide lactone.
  • Muscolide from 14-methylpentan decano-15-lactone.

Macrocyclic ketone musks.

These are musks made from ketone rings made of 10-15 carbons. They are synthesized to imitate animal-derived musks.

They include the following:

  • Muscone from 3-methyl cyclopentadecanone ketone.
  • Civetone from 9-cycloheptadecen-1-one ketone.
  • Exaltone from cyclopentadecanone.
  • Ambretone and T.M II SP from 5-cyclohexadecane-1-one.

Is galaxolide toxic?

No, the bioaccumulation and toxicity tests of galaxolide have been conducted by different agencies and it was concluded that galaxolide is non-toxic and has very low bioaccumulation in the human body.

Some people have concerns about using galaxolide though because it is classified as a polycyclic musk.. polycyclic musks have been categorized as being carcinogenic.

Is galaxolide eco-friendly?

Eco-friendliness is the ability of a substance to not pose any threat to the environment. 

The eco-friendliness of galaxolide has been questioned for some time now. 

Galaxolide is classified as a very toxic substance to aquatic life.

Research has shown that galaxolide levels have been rising in lakes and rivers. This has raised the question of the safety of aquatic life. A study on the safety of galaxolide showed that some lakes in the USA contained up to 81% of galaxolide.

Conclusion.

This article has answered the question of the biodegradability of galaxolide.

It has also addressed other areas such as:

  • Properties and uses of galaxolide.
  • Classes of musks.
  • Properties of natural and synthetic musks.
  • Eco-friendliness and toxicity of galaxolide.

For any questions or comments please use the comment section below.

Frequently Asked Questions (FAQs): is galaxolide biodegradable?

What is galaxolide?

Galaxolide is a synthetic chemical that is used as a perfume fixative to give a musky odor to fragrances. 

Is galaxolide harmful?

There have been concerns over the use of galaxolide. Some studies have shown that it may interfere with hormones and other body functions. These claims are yet to be substantiated and galaxolide remains a safe compound to use.

What does galaxolide smell like?

Galaxolide smells like a clean, sweet, floral, woody musk. It is designed to imitate the natural smell of muscone aromatic compounds that are found in the substance released by the glands of the musk deer.

Citations.

The laundry guru. ( May 20, 2018). The Hidden Dangers of Galaxolide. An article on Molly’s SUDs.

Retrieved from:

Rowe, David J. (Ed.); Philip Kraft (2004). “Chapter 7. Aroma Chemicals IV: Musks”. Chemistry and Technology of Flavours and Fragrances. Blackwell. ISBN 0-8493-2372-X.

Fráter, Georg; Müller, Urs; Kraft, Philip (1999). “Preparation and Olfactory Characterization of the Enantiomerically Pure Isomers of the Perfumery Synthetic Galaxolide”. Helvetica Chimica Acta. 82 (10): 1656–65. doi:10.1002/(SICI)1522-2675(19991006)8

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