What Is Crotonaldehyde?
Crotonaldehyde is an organic compound that is classified as an unsaturated aldehyde.
Its molecular formula is C4H6O, and it has one double bond in the molecule. There are two types of geometric isomers, cis and trans, but the trans form is often referred to without any special mention.
The CAS registration numbers are 123-73-9 (trans), 15798-64-8 (cis), and 4170-30-3 (mixture), and the IUPAC nomenclature names are
“(E)-2-butenal” and “(Z)-2-butenal” for the trans and cis forms, respectively.
Other names such as “propylenaldehyde,” “methyl propenal,” and “β-methylacrolein” may also be used.
Uses of Crotonaldehyde
The main uses of crotonaldehyde are as a raw material for synthesizing organic compounds, such as butanol, butyl alcohol, crotonic acid, and sorbic acid. These compounds are used in various industrial products.
For example, butanol, which is synthesized using crotonaldehyde, is widely used in color paints, brake fluid, and fuels.
Crotonaldehyde is also used as a raw material for pharmaceuticals and agrochemicals due to its high synthetic value.
It is also used as a raw material for organic synthesis in research and development.
Characteristics of Crotonaldehyde
As mentioned above, there are two types of geometric isomers of crotonaldehyde: cis- and trans-forms. The trans form, which is mainly used, has a melting point of -76.5°C, a boiling point of 104.0°C, and a density of 0.853 g/cm3 (20°C).
The cis form has a melting point of -69°C (-69°F), but other physical properties information is less clear due to its limited use. It exists in liquid form at room temperature and is colorless and transparent.
It is characterized by a pale yellow color and pungent odor when exposed to light or air.
Types of Crotonaldehyde
As mentioned above, there are two geometric isomers of crotonaldehyde, but the trans form is mainly used. Therefore, most of the products sold are trans isomers.
The trans isomer is mainly sold as a reagent product for research and development of organic synthesis, and is available in easy-to-handle laboratory volumes such as 25mL and 500mL. Acetonitrile, water, and methanol solutions also exist as products.
On the other hand, cis/trans mixtures can be purchased as pharmaceutical and agrochemical raw materials for industrial use. This product is available in tanker trucks, drums, oil cans, and other large cargoes for factory applications.
Other Information on Crotonaldehyde
1. Synthesis and Chemical Reaction of Crotonaldehyde
Crotonaldehyde is synthesized mainly by condensation of acetaldehyde. It can also be obtained by heating aldol with a mineral acid and distilling the reactants.
As for the reactivity of crotonaldehyde, it has an aldehyde group, which makes it easy to polymerize. In addition, when left in the air, it is gradually oxidized by oxygen in the air to crotonic acid.
2. Regulatory Information on Crotonaldehyde
Crotonaldehyde is a flammable substance with a low flash point of 13℃.
In addition, the vapor has a strong pungent odor, is tearing, and is known to be toxic.
When handling these substances, care must be taken, including the use of goggles.