Methyl butyrate

Description

Methyl butyrate, also known as methyl butanoate , is an ester with a fruity odor pineapple, apple, and strawberry. At room temperature, it is a colorless liquid with low solubility in water, upon which it floats to form an oily layer. Although it is flammable, it has a relatively low vapor pressure ( 40 mmHg at 30°C), so it can be safely handled at room temperature without special safety precautions.

Chemical properties

Methyl butyrate is colourless liquid that has an apple-like odor and a corresponding sweet taste that is not very powerful. Below 100 ppm, it may have a banana-pineapple flavor. Miscible in ethanol and ether, slightly soluble in water (1:60). May be prepared from methyl alcohol and butyric acid in the presence of concentrated H2S04.

Occurrence

Metyhl butyrate occurs naturally in pineapple oil, round grapefruit juice, apple juice, kiwi and mushrooms. It is used as a flavor ingredient in fruit and rum flavoring for beverages, ice cream, candy, and baked goods.

The Uses of Methyl butyrate

Methyl butyrate is used as a solvent for ethylcellulose and nitrocellulose resins. It is also used in lacquers and perfumes and in the manufacture of rum and fruit flavors.

Preparation

Methyl butyrate is produced from methyl alcohol and butyric acid in the presence of concentrated sulfuric acid. The synthesis of methyl butyrate by the reaction between butyric acid and methanol with acidic ion exchange resin as a catalyst in presence of ultrasound irradiation was successfully carried out.

Definition

ChEBI: Methyl butyrate is a fatty acid ester.

What are the applications of Application

Methyl butyrate is an important raw material and intermediate used in organic synthesis, pharmaceuticals, agrochemicals and dyestuff fields.

Aroma threshold values

Detection: 1 to 43 ppb. Aroma characteristics at 1.0%: pungent, ethereal, fruity, fumey and fusel with a fermented, cultured, creamy undernote.

Taste threshold values

Taste characteristics at 10 ppm: fruity and apple-like with a sweet almost buttery, nutty and creamy nuance, fusel-like, impacting, and estry with a cultured dairy, acidic depth.

Synthesis Reference(s)

Tetrahedron Letters, 29, p. 1759, 1988 DOI: 10.1016/S0040-4039(00)82035-3

General Description

Methyl butyrate appears as a clear colorless liquid. Flash point 57°F. Less dense than water and slightly soluble in water. Hence floats on water. Vapors heavier than air.

Air & Water Reactions

Highly flammable. Slightly soluble in water.

Reactivity Profile

Methyl butyrate reacts exothermically with acids to generate alcohols and carboxylic acids. Strong oxidizing acids may cause a reaction that is sufficiently exothermic to ignite the reaction products. Heat is also generated by interaction with basic or caustic solutions. Flammable hydrogen is generated by mixing with alkali metals and hydrides .

Hazard

Flammable, dangerous fire risk.

Health Hazard

Irritating to the eyes, nose, throat, upper respiratory tract, and skin.

Fire Hazard

HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

Industrial uses

Methyl butyrate is occasionally used as a masking agent in industrial perfumes especially where the problem is to mask very volatile malodors, etc. The type of odor is particularly suitable to cover sulfuraceous odors.
It is, however, much more widely used in flavor compositions for imitation Apple, Banana, Pineapple, Melon, Peach, Rum and Arak, and in various fruit complexes. The concentration used is equivalent to about 20 to 100 ppm in the finished consumer product.

Safety Profile

Moderately toxic by ingestion and skin contact. A skin irritant. A very dangerous fire hazard when exposed to heat, flame, or oxidizers. Can react vigorously with oxidizing materials. To fight fire, use alcohol foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes. See also ESTERS.

Potential Exposure

Methyl butyrate, one of the odorous compound present in different types of adhesive (hotmelt, vinyl acetate ethylene, starch, polyvinyl acetate and acrylic) used in food packaging, was identified by GC-O-MS (gas chromatography–mass spectrometry–olfactometry).

Carcinogenicity

Not listed by ACGIH, California Proposition 65, IARC, NTP, or OSHA.

Purification Methods

Treat the ester with anhydrous CuSO4, then distil it under dry nitrogen. [Beilstein 2 IV 786.]

References

[1] Ruth Winter, A Consumer's Dictionary of Food Additives, 7th Edition, 2009
[2] Laurent Ducry and Dominique M. Roberge, Dibal-H Reduction of Methyl Butyrate into Butyraldehyde using Microreactors, Organic Process Research & Development, 2008, vol. 12, 163-167