Introduction

Esters and lactones are one of the most versatile groups of chemicals used in fragrances. They do everything from acting as simple, odorless solvents to creating distinctive smells like bananas and oud. This broad range makes esters incredibly useful to perfumers, who rely on them to design scents ranging from straightforward and fresh to deep and complex.

But why exactly are esters so popular in perfumery? It’s because they easily fit into almost any type of fragrance. They can smell fresh and fruity like apples or pears, floral like jasmine or roses, or deep and woody like sandalwood or oud. Beyond just smelling nice, esters also help perfumes last longer and perform better by working as solvents and stabilizers.

There’s also a unique group of esters called lactones, known for their creamy, milky, or coconut-like scents. Lactones are especially popular in fragrances that smell edible, creamy, or rich, often giving perfumes a comforting or luxurious quality. In this post, we’ll take a closer look at esters and lactones, discussing their chemistry, the wide variety of scents they produce, and why they’re essential in fragrance creation. Whether you’re curious about the fruity notes of ethyl acetate or the creamy texture of gamma-decalactone, esters and lactones offer plenty of exciting aromas to explore.

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Esters and Lactones

Esters are a type of chemical compound formed when a carbon atom is attached to two oxygen atoms—one with a double bond (carbonyl group, C=O) and the other with a single bond (alkoxy group, -O-) that’s connected to another carbon atom. Esters typically form through a chemical reaction between an alcohol and a carboxylic acid, where they lose a water molecule in the process. A simple example is ethyl acetate, which forms when ethanol (a type of alcohol) reacts with acetic acid (like the acid found in vinegar). Chemists call this reaction esterification, and it’s common both in nature and in industrial settings.

Usually, when someone talks about esters, they’re referring to carboxylic esters, but it’s worth mentioning that esters can also come from other types of acids. For example, sulfuric acid can create sulfate esters, and phosphoric acid can form phosphate esters. Still, in perfumery and most organic chemistry contexts, people typically mean carboxylic esters unless they specifically mention otherwise.

Naming esters is pretty straightforward. You start with the alcohol component (the alkyl group) and finish with the acid part, changing its ending (-ic or -oic) to -ate. For example, “ethyl acetate” takes its name from ethanol (the “ethyl” part) and acetic acid (the “acetate” part).

Lactones: Cyclic Esters

Lactones are special kinds of esters that form ring structures, making them known as cyclic esters. These rings are created when a molecule with both an alcohol group (–OH) and a carboxylic acid group (–COOH) reacts with itself, closing into a loop and creating an ester link. This ring structure gives lactones unique scents that are especially popular in perfumes. Lactones typically smell creamy, milky, or even coconut-like. They’re often found in perfumes designed to smell like sweet foods or to enhance floral fragrances, adding richness and depth.

Lactones have their own naming style, usually involving Greek letters that show the size of the ring and the position of the alcohol group relative to the ester.

• Gamma (γ) Lactones: These have five-membered rings. In γ-lactones, the alcohol group connects to the third carbon atom after the ester group. A common γ-lactone is γ-undecalactone, where “γ” means a five-membered ring, and “undeca” refers to its 11 carbon atoms. Sometimes these are called butenolides.
• Delta (δ) Lactones: These lactones have six-membered rings. Here, the alcohol group attaches to the fourth carbon atom from the ester group. Delta lactones, especially those with large rings (macrocyclic lactones), are famous for their musk-like scents in perfumes.

The ring shape of lactones makes their scents extremely diverse, ranging from fruity and fresh to deeply musky. Because of their creamy character, lactones add smoothness and comfort to fragrance blends, making perfumes feel more natural and luxurious. Especially large-ring lactones provide a subtle, long-lasting scent, helping fragrances feel richer and more sophisticated.

Esters and Lactones in Perfumery

There’s a huge variety of esters used in perfumes, making it hard to highlight just a few. Still, here are some popular and interesting esters and lactones that show just how flexible and useful these chemicals are for creating memorable scents.

Esters

• Linalyl acetate (CAS: 115-95-7): Has a fresh, clean scent that’s somewhere between bergamot and lavender, bringing a delicate floral and citrus touch. It is found in natural oils such as bergamot, cardamom, clary sage, lavandin, lavender, neroli, and orange. Linalyl acetate is widely used in both fine fragrances and personal care products for its light, refreshing note that blends well with a variety of scent families.
• Ethyl 2-methylpentanoate (Manzanate) (CAS: 39255-32-8): A unique mix of red fruits, valerian root, pineapple, and melon. This ester offers a juicy, exotic scent that is especially useful in fruity accords. Popular in personal care products, it adds a sweet, tropical fruitiness to fragrances and enhances the sensory experience of fruity and gourmand compositions.
• Ethyl caproate (CAS: 123-66-0): Ethyl caproate is prized for its bright, juicy pineapple scent. It is often used in fruity fragrance compositions, particularly when a realistic tropical or fresh note is needed. Its vibrant aroma makes it indispensable for adding a sunny, playful character to perfumes.
• Styrallyl acetate (CAS: 93-92-5): This ester has a sharp, green floral scent with fresh, crisp nuances. It is a key ingredient in creating sharp, masculine fragrance notes. Styrallyl acetate is frequently used in perfumes targeting male consumers, lending a modern, clean scent with an almost metallic edge.
• Benzyl acetate (CAS: 140-11-4): Known for its sweet, floral, and somewhat fruity scent, reminiscent of jasmine and ylang-ylang. Benzyl acetate is one of the most widely used esters in perfumery due to its intensity and affordability. It plays a crucial role in many floral and fruity compositions, and its versatility makes it a go-to raw material for perfumers.
• Hexyl salicylate (CAS: 6259-76-3): A fresh, floral, and slightly sweet scent, often associated with the “shampoo” note. Hexyl salicylate is frequently used in hair care products and fine fragrances. Interestingly, there is also cis-3-hexenyl salicylate (CAS: 65405-77-8), which has a more intense floral scent and is primarily used in women’s fine fragrances to introduce a delicate, green floral note.
• Para-cresyl acetate (CAS: 140-39-6): This ester has a strong, animalic, oud-like scent with sharp, leathery undertones. Para-cresyl acetate is a popular choice in oriental fragrances for its deep, rich, and intense olfactory profile. It helps to add an exotic and sophisticated edge to oud-based perfumes.
• Diethyl phthalate (CAS: 84-66-2): While diethyl phthalate doesn’t contribute a notable scent, it serves as a solvent. Different from other phthalates that are banned in cosmetics, diethyl phthalate is still used as a solvent in many industrial products, including perfumes. It enhances the longevity and consistency of fragrances without contributing a distinct odor.

Lactones

• Gamma-undecalactone (Aldehyde C14) (CAS: 104-67-6): This lactone is often associated with a juicy, peach-like scent. Though mentioned in the aldehydes blog post, gamma-undecalactone is technically a lactone and is frequently used in fruity fragrance compositions. Its creamy peach aroma adds softness and warmth to both sweet and floral fragrances.
• Ethyl 3-Methyl-3-Phenyloxirane-2-Carboxylate (Aldehyde C16) (CAS: 77-83-8): Despite its name, this molecule is actually a lactone, known for its sweet, fruity-strawberry note. Often referred to as Aldehyde C16, this imposter lactone provides a sugary, strawberry scent that is commonly used in fruity and floral compositions.
• Gamma-Nonalactone (Aldehyde C18) (CAS: 104-61-0): Known for its coconut-like aroma. Another imposter lactone, often referred to as Aldehyde C18, is key in creating creamy, tropical accords. It is particularly valuable in exotic or gourmand fragrance compositions, contributing a smooth, rich coconut note.
• Delta-Decalactone (CAS: 705-86-2): A rich, creamy coconut scent that is more robust and long-lasting than other lactones. Delta-decalactone is a favorite in gourmand fragrances, adding a velvety, edible character that enhances both sweet and tropical profiles.
• Ambrettolide (CAS: 7779-50-2): Ambrettolide has a warm, musky, and slightly sweet aroma, with nuances of amber. One of the most commonly used macrocyclic musks, ambrettolide is prized for its longevity and ability to impart a sensual, luxurious quality to perfumes.
• Coumarin (CAS: 91-64-5): Coumarin has a sweet, tonka bean, hay-like scent with a slight bitterness. One of the first molecules to be synthesized for use in perfumes, coumarin is a cornerstone of many fragrance compositions. Its rich, warm aroma is often used to add depth to oriental and gourmand perfumes.
• Habanolide (CAS: 111879-80-2): Habanolide has a clean, musky scent that is so prominent in modern perfumery that it is often described as “perfumy”. Frequently used in amber and musky fragrances, habanolide adds a smooth, sensual quality to both men’s and women’s perfumes. Its widespread use has made it synonymous with the classic “perfume” scent.

These lactones provide perfumers with a wide range of appealing scents, from fruity peaches and strawberries to rich coconut and warm musky notes. Their versatility makes them essential ingredients in creating balanced and captivating fragrances.

Stability of Esters and Lactones in Fragrance

Esters and lactones are key ingredients in perfumes, known for their fresh, fruity, floral, creamy, and sometimes musky scents. While they create some of the most appealing fragrance notes, their stability can be affected by different conditions. Keeping these compounds stable helps ensure perfumes stay true to their original smell over time.

Stability of Esters

Esters usually stay stable in fragrances, but certain factors can cause them to degrade or change their scent. Here’s what typically impacts their stability:

• Hydrolysis: One of the main reactions that can affect esters is hydrolysis, where the ester reacts with water and breaks down into its original alcohol and acid components. In the case of esters, this reaction is more likely to happen in the presence of moisture and at high temperatures. Over time, hydrolysis can lead to changes in the scent, as the breakdown products often have different odors from the original ester. For example, ethyl acetate, when exposed to water, can break down into ethanol and acetic acid, which have distinctly different scent profiles.
• pH Sensitivity: Esters are sensitive to changes in pH. In highly acidic or highly alkaline environments, they may break down more rapidly, leading to a loss of their intended scent. Proper formulation techniques ensure that the pH remains balanced, preserving the ester’s longevity in the fragrance.
• Light and Heat: Exposure to sunlight (UV light) and high temperatures can accelerate the degradation of esters. These conditions can cause oxidation or other chemical reactions that alter the ester’s structure, potentially leading to a loss of potency or the development of unwanted off-notes. To prevent this, perfumes are often stored in dark or opaque bottles to reduce exposure to light.

Stability of Lactones

Lactones, being cyclic esters, tend to be more stable than regular esters. Their ring structure helps them resist breaking down from hydrolysis and oxidation, so they typically last longer in perfume formulations. Still, they can be affected by heat, moisture, and prolonged exposure to harsh conditions.

Conclusion

Esters and lactones are incredibly valuable in the world of fragrance, offering a wide variety of scents that range from fruity and floral to creamy and musky. Chemically related to carboxylic acids but much more pleasant smelling, esters are formed from reactions between alcohols and acids, providing the basis for many fresh, appealing aromas in perfumery. Lactones, a special type of cyclic ester, bring unique creamy, coconut, and fruity nuances that enrich fragrances even further.

Not only do esters and lactones create appealing scents, but they also have practical uses, helping fragrances last longer and mix better due to their varying evaporation rates. Their stability can be influenced by moisture, pH levels, heat, and light exposure, so careful formulation and storage are important to maintain their integrity.

Overall, esters and lactones are fundamental ingredients in perfumery, giving perfumers the ability to craft everything from simple, refreshing fragrances to complex, luxurious scents. Understanding their chemistry, versatility, and stability allows us to appreciate just how essential these compounds are in creating perfumes that are both captivating and enduring.

Take care of yourselves and your noses.

References and Further Reading

For those eager to delve deeper into the world of perfumery, here are some resources for further exploration:

Books:

• Chemistry and the Sense of Smell by Charles S. Sell
• Fundamentals of Fragrance Chemistry by Charles S. Sell
• Chemical Bonds.An Introduction to Atomic and Molecular Structure by Harry B. Gray

Scientific Papers, Journals and Blog Posts:

Carboxylic acids and derivatives – Khan Academy