An ester of carboxylic acid. R stands for any group (organic or inorganic) and R′ stands for organyl group.

In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (−R). Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well (i.e. esters of acidic −SH, −SeH, −TeH, −PoH and −LvH groups). According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC.^[1]

An example of an ester formation is the substitution reaction between a carboxylic acid (R−C(=O)−OH) and an alcohol (R'OH), forming an ester (R−C(=O)−O−R'), where R and R′ are organyl groups, or H in the case of esters of formic acid. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the main classes of lipids, and making up the bulk of animal fats and vegetable oils. Esters of carboxylic acids with low molecular weight are commonly used as fragrances and found in essential oils and pheromones. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. Esters of carboxylic acids usually have a sweet smell and are considered high-quality solvents for a broad array of plastics, plasticizers, resins, and lacquers.^[2] They are also one of the largest classes of synthetic lubricants on the commercial market.^[3]

By number of R' group carbons (R−C(=O)−O−R')

1 carbon

Name	Structure
Methyl nitrate[4]
Methyl formate[5]
Methyl acetate[6]
Methyl acrylate
Methyl propionate[7]
Methyl butyrate[8]
Methyl pentanoate[9]
Methyl benzoate[10]
Methyl anthranilate[11]
Methyl salicylate[12]
Methyl phenylacetate[13]
Methyl cinnamate[14]

2 carbons

Name	Structure
Ethyl formate[15]
Ethyl acetate[16]
Ethyl propionate[17]
Ethyl lactate[18]
Ethyl butyrate[19]
Ethyl pentanoate[20]
Ethyl isovalerate[21]
Ethyl hexanoate[22]
Ethyl heptanoate[23]
Ethyl benzoate[24]
Ethyl salicylate[25]
Ethyl octanoate[26]
Ethyl cinnamate[27]
Ethyl decanoate[28]

3 carbons

Name	Structure
Propyl acetate
Propyl propanoate
Propyl hexanoate
Allyl hexanoate
Isopropyl acetate
Isopropyl salicylate
Isopropyl palmitate

4 carbons

Name	Structure
Butyl formate
Butyl acetate
Isobutyl formate
Isobutyl acetate
Sec-Butyl formate
Sec-Butyl acetate
Tert-Butyl formate
Tert-Butyl acetate
Butyl butyrate

5 carbons

Name	Structure
Amyl acetate
Pentyl butyrate
Pentyl propanoate
Pentyl hexanoate
Sec-Amyl acetate

7 carbons

Name	Structure
Benzyl acetate

8 carbons

Name	Structure
Octyl acetate

10 carbons

Name	Structure
Geranyl acetate
Bornyl acetate
Linalyl acetate

By number of R group carbons (R−C(=O)−O−R')

0 carbons

Name	Structure
Methyl nitrate

1 carbon

Name	Structure
Methyl formate
Ethyl formate
Isobutyl formate

2 carbons

Name	Structure
Methyl acetate
Ethyl acetate
Propyl acetate
Butyl acetate
Amyl acetate
Benzyl acetate
Octyl acetate
Geranyl acetate
Bornyl acetate
Linalyl acetate

3 carbons

Name	Structure
Methyl propionate
Ethyl propionate
Propyl propanoate
Pentyl propanoate
Ethyl lactate

4 carbons

Name	Structure
Methyl butyrate
Ethyl butyrate
Butyl butyrate
Pentyl butyrate

5 carbons

Name	Structure
Methyl pentanoate
Ethyl pentanoate
Pentyl pentanoate
Ethyl isovalerate

6 carbons

Name	Structure
Ethyl hexanoate
Propyl hexanoate
Allyl hexanoate
Pentyl hexanoate

7 carbons

Name	Structure
Ethyl heptanoate
Methyl benzoate
Ethyl benzoate
Methyl anthranilate
Methyl salicylate
Ethyl salicylate
Isopropyl salicylate

8 carbons

Name	Structure
Ethyl octanoate
Methyl phenylacetate

9 carbons

Name	Structure
Methyl cinnamate
Ethyl cinnamate

10 carbons

Name	Structure
Ethyl decanoate

16 carbons

Name	Structure
Isopropyl palmitate

List of ester odorants

Many esters of carboxylic acid have distinctive fruit-like odors, and many occur naturally in fruits and the essential oils of plants. This has also led to their common use in artificial flavorings and fragrances which aim to mimic those odors.

Ester name	Structure	Odor or occurrence
Allyl hexanoate		pineapple
Benzyl acetate		pear, strawberry, jasmine
Bornyl acetate		pine
Butyl acetate		apple, honey
Butyl butyrate		pineapple
Butyl propanoate		pear drops
Ethyl acetate		nail polish remover, model paint, model airplane glue
Ethyl benzoate		sweet, wintergreen, fruity, medicinal, cherry, grape
Ethyl butyrate		banana, pineapple, strawberry
Ethyl hexanoate		pineapple, waxy-green banana
Ethyl cinnamate		cinnamon
Ethyl formate		lemon, rum, strawberry
Ethyl heptanoate		apricot, cherry, grape, raspberry
Ethyl isovalerate		apple
Ethyl lactate		butter, cream
Ethyl nonanoate		grape
Ethyl pentanoate		apple
Geranyl acetate		geranium
Geranyl butyrate		cherry
Geranyl pentanoate		apple
Isobutyl acetate		cherry, raspberry, strawberry
Isobutyl formate		raspberry
Isoamyl acetate		pear, banana (flavoring in Pear drops)
Isopropyl acetate		fruity
Linalyl acetate		lavender, sage
Linalyl butyrate		peach
Linalyl formate		apple, peach
Methyl acetate		glue
Methyl anthranilate		grape, jasmine
Methyl benzoate		fruity, ylang ylang, feijoa
Methyl butyrate (methyl butanoate)		pineapple, apple, strawberry
Methyl cinnamate		strawberry
Methyl pentanoate (methyl valerate)		flowery
Methyl phenylacetate		honey
Methyl salicylate (oil of wintergreen)		Modern root beer, wintergreen, Germolene and Ralgex ointments (UK)
Nonyl caprylate		orange
Octyl acetate		fruity-orange
Octyl butyrate		parsnip
Amyl acetate (pentyl acetate)		apple, banana
Pentyl butyrate (amyl butyrate)		apricot, pear, pineapple
Pentyl hexanoate (amyl caproate)		apple, pineapple
Pentyl pentanoate (amyl valerate)		apple
Propyl acetate		pear
Propyl hexanoate		blackberry, pineapple, cheese, wine
Propyl isobutyrate		rum
Terpenyl butyrate		cherry

Lactones

Lactones are a specific class cyclic carboxylic esters that are formed through intramolecular esterification.

Lactone name	Structure
β-propiolactone
γ-butyrolactone (GBL)
D-glucono-δ-lactone (E575)
ε-caprolactone

References