The key difference between Delrin and acetal is that Delrin is a polymer material having the repeating unit (CH2O) whereas acetal is a functional group having the chemical formula R2C(OR’)2.
The polymer material Delrin is sometimes commonly named as acetal; thus, it is often confused with the term acetal, which describes a type of functional group in organic chemistry.
CONTENTS
1. Overview and Key Difference
2. What is Delrin (or POM)
3. What is Acetal
4. Side by Side Comparison – Delrin vs Acetal in Tabular Form
5. Summary
What is Delrin ( or POM)?
Delrin is the trade name for the polymer material polyoxymethylene or POM. It is also named as acetal, polyacetal and polyformaldehyde in polymer chemistry. It is a type of engineering thermoplastic material that is useful in precision parts requiring high stiffness, low friction, and excellent dimensional stability. It is a type of synthetic polymer material. This material is produced by different chemical firms with slightly different formulas, and these are sold using different names, including Delrin, Kocetal, Ultraform, Celcon, etc.
Figure 01: Structure of the Repeating Unit of Delrin Polymer
As characteristic features, we can observe the high strength, hardness and rigidity at very low temperatures. Intrinsically, this material is opaque white, which arises due to its high crystalline composition. However, it is available in different colours as well in commercial scale.
When considering the production of Delrin, we can produce it in the form of a homopolymer or in the form of a copolymer. We can produce the homopolymer by the reaction of the aqueous formaldehyde with an alcohol to create a hemiformal, dehydration of the hemiformal/water mixture, followed by the release of the formaldehyde by heating the hemiformal. Thereafter, the hemiformal is polymerized through anionic catalysis to get the desired product.
What is Acetal?
Acetal is a functional group having the chemical formula R2C(OR’)2. In this chemical formula, the R groups are either organic fragments or hydrogen while the R’ groups are only organic fragments but not hydrogen. Moreover, the two R’ groups can be equivalent to each other, giving a symmetrical acetal. If they are not equivalent, then we can get a mixed acetal.
Figure 02: Chemical Structure of Acetal Functional Group in Organic Chemistry
Typically, acetals are convertible to aldehydes or ketones. Therefore, they have the same oxidation state at the central carbon atom. However, the convertible forms have different chemical stability and reactivity when compared to the analogous carbonyl compounds. Moreover, the central carbon atom of an acetal group has the valency of four – meaning, four covalent bonds around it, making the carbon centre saturated. Also, this carbon centre has a tetrahedral geometry.
What is the Difference Between Delrin and Acetal?
Delrin and acetal are important organic compounds. Delrin is the trade name for the polymer material polyoxymethylene or POM. The key difference between Delrin and acetal is that Delrin is a polymer material having the repeating unit (CH2O) whereas acetal is a functional group having the chemical formula R2C(OR’)2. Moreover, Deril contains a large number of repeating units of CH2O while acetal contains a saturated tetrahedral carbon centre bonded to an R group(or a hydrogen atom), two R’O groups and a hydrogen atom.
Below infographic lists the differences between Delrin and acetal in tabular form.
Summary – Delrin vs Acetal
Generally, the term acetal is used as a common, general term to describe Delrin. However, the term acetal in organic chemistry describes a specific organic chemical functional group. The key difference between Delrin and acetal is that Delrin is a polymer material having the repeating unit (CH2O) whereas acetal is a functional group having the chemical formula R2C(OR’)2.
Reference:
1. “14.3: Acetal Formation.” Chemistry LibreTexts, Libretexts, 11 Aug. 2020, Available here.
Image Courtesy:
1. “Polyoxymethylene” By Yikrazuul – Own work (Public Domain) via Commons Wikimedia
2. “Acetal general structure” (Public Domain) via Commons Wikimedia
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