Difference Between Allyl and Vinyl

Key Difference – Allyl vs Vinyl
 

Both allyl and vinyl groups have slightly similar structures with a small variation. Both groups own a double bond between two carbon atoms where all the other atoms are bonded through single bonds. The key difference between these two structural components is the number of carbon and hydrogen atoms. Allyl groups have three carbon atoms and five hydrogen atoms whereas vinyl groups have two carbon atoms and three hydrogen atoms. The –R group in the structure can be any group with any number of atoms with any type of bonding pattern.

What is an Allyl Group?

An allyl group is a substituent with the structural formula H₂C=CH-CH₂-R; where –R is the rest of the molecule. Therefore, allyl group is a part of a molecule which is equivalent to a propane molecule after eliminating one hydrogen atom from the third Carbon atom. That hydrogen atom is replaced by any other –R group to form a molecule. The word ‘allyl’ is a Latin word used for garlic, Allium sativum. Since an allyl derivative was first isolated from garlic oil, it was named “Schwefelallyl” by Theodor Wertheim in 1844.

What is a Vinyl Group?

The alkenyl functional group vinyl is also known as ethenyl (-CH=CH₂); it is equivalent to an ethylene molecule (CH₂=CH₂) after removing one hydrogen atom. The removed –H atom can be replaced by any other group of atoms to form a molecule (R−CH=CH₂). This group is very important in some industrial applications.

What is the difference between Allyl and Vinyl?

Structure

Allyl: When one hydrogen atom is removed from the third carbon atom of a propane molecule, it is equivalent to an allyl group. It contains two sp² hybridized carbon atoms and one sp³ hybridized carbon atom. In other words, it is a methylene bridge (-CH₂-) attached to a vinyl group (-CH=CH₂).

Vinyl: The structure of a vinyl group is equivalent to the molecular group when one hydrogen atom is removed from an ethene molecule. Therefore, it is also known as an ethenyl group. It contains two sp² hybridized carbon atoms and three hydrogen atoms. The removed hydrogen atom can be replaced by any group of molecules, and it is denoted as –R.

Examples of Derivatives

Allyl: Allyl groups form very stable compounds when substituents are attached. It forms compounds in several areas such as organic compounds, biochemical compounds, and metal complexes.

Organic Compounds:

Allyl Alcohol: H₂C=CH-CH₂OH (the parent of allylic alcohols)

Allyl Chloride: They exist as substituted versions of the parent allyl group. Examples are trans-but-2-en-1-yl or crotyl group (CH₃CH=CH-CH₂-).

Biochemistry:

Dimethylallyl Pyrophosphate: It is in the biosynthesis of terpenes.

Isopentenyl Pyrophosphate: It is a homoallylic isomer of the dimethylallyl compound. It is also used as a ^*precursor to many natural products such as natural rubber.

Metal Complexes:

Allyl ligands bind to metallic centers through its three carbon atoms. One example is; Allyl Palladium Chloride.

Vinyl: Most of vinyl derivatives are used in polymer industry. Examples are; Vinyl Chloride, Vinyl Fluoride, Vinyl Acetate, Vinylidene, and Vinylene.

Uses:

Allyl: Allyl compounds are of a wide range and are used in several areas. For example; allyl chloride is used to produce plastics and used as an alkylating agent.

Vinyl: One of the best examples of an industrial application of vinyl group is vinyl chloride (CH₂=CH-Cl). It is used as a precursor to manufacture polyvinyl chloride (PVC). It is the third most widely produced synthetic plastic variety in the world. In addition, it is used to produce vinyl fluoride and vinyl acetate to produce two other polymers; polyvinyl fluoride (PVF) and polyvinyl acetate (PVAc) respectively.

Vinyl gloves are used in medicine due to its poor resistance to many chemicals, less flexibility, and elasticity.

Definitions:

^*Precursor: a precursor is a substance that participates in a chemical reaction that produces another compound.

References:

Romanowski, Frank and Herbert Klenk. “Thiocyanates And Isothiocyanates, Organic”. Ullmann’s Encyclopedia of Industrial Chemistry (2000): n. p. Web. 26 May 2016.

“Illustrated Glossary Of Organic Chemistry – Allyl Group”. Chem.ucla.edu. N.p., 2016. Web. 26 May 2016.