Sign In

An allyl group is a three-carbon conjugated system where the sp³-hybridized allylic carbon is bonded to a CH=CH2group via a single bond. Allyl anions can be obtained by treating propene with a strong base that can deprotonate methyl groups. Allyl cations are formed as intermediates during substitution reactions involving allylic halides. In both cases, the hybridization of the allylic carbon changes from sp3 to sp2, giving rise to a carbon chain with three sp2-hybridized carbons, each with an unhybridized p orbital.

A linear combination of the three atomic p orbitals gives three molecular orbitals, ψ1, ψ2, and ψ3. ψ1 is the bonding molecular orbital, ψ2 is a nonbonding orbital characterized by a node passing through the central carbon, whereas ψ3 is an antibonding molecular orbital with two nodes. The molecular orbital frameworks of the allyl anion and cation are identical and differ only in the number of π electrons. The allyl cation has two π electrons in ψ1, whereas the allyl anion has four π electrons distributed between ψ1 and ψ2.

Figure1

Tags

Molecular Orbitals Of The Allyl Cation And AnionAllyl GroupSp2 hybridized Allylic CarbonAllyl AnionAllyl CationConjugated SystemMolecular OrbitalsBonding OrbitalNonbonding OrbitalAntibonding OrbitalElectrons

From Chapter 16:

article

Now Playing

16.4 : π Molecular Orbitals of the Allyl Cation and Anion

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

4.0K Views

article

16.1 : מבנה הדיינים המצומדים

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

4.5K Views

article

16.2 : יציבות של דיינים מצומדים

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

3.2K Views

article

16.3 : π אורביטלים מולקולריים של 1,3-בוטאדיאן

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

8.3K Views

article

16.5 : π אורביטלים מולקולריים של רדיקל אליל

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

3.3K Views

article

16.6 : אלקטרופילי 1,2- ו 1,4 תוספת של HX ל 1,3-Butadiene

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

4.9K Views

article

16.7 : אלקטרופילי 1,2- ו 1,4-תוספת של x2 ל 1,3-butadiene

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

2.2K Views

article

16.8 : תוספת אלקטרופילית של HX ל-1,3-בוטאדיאן: בקרה תרמודינמית לעומת קינטית

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

2.3K Views

article

16.9 : ספקטרוסקופיית UV–Vis של מערכות מצומדות

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

6.7K Views

article

16.10 : ספקטרוסקופיית UV–Vis: חוקי וודוורד–פייזר

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

23.0K Views

article

16.11 : תגובות פריציקליות: מבוא

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

8.1K Views

article

16.12 : תגובות אלקטרוציקליות תרמיות ופוטוכימיות: סקירה כללית

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

2.2K Views

article

16.13 : תגובות אלקטרוציקליות תרמיות: סטריאוכימיה

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

1.9K Views

article

16.14 : תגובות אלקטרוציקליות פוטוכימיות: סטריאוכימיה

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

1.8K Views

article

16.15 : Cycloaddition תגובות: סקירה כללית

Dienes, Conjugated Pi Systems, and Pericyclic Reactions

2.5K Views

See More

JoVE Logo

Privacy

Terms of Use

Policies

Research

Education

ABOUT JoVE

Copyright © 2025 MyJoVE Corporation. All rights reserved