Lecture11 F08 given

Lecture11 F08 given - Lecture 11 Organic Chemistry I Prof....

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Organic Chemistry I 310/318M Pre-Health Professionals Unique numbers: 54410, 54435, 54440, 54445, and 54655 Prof. Jonathan L. Sessler Lecture 11 Note: Homework 2 will be due on Wednesday. Homework 3 will be due on the 1st (day before exam I). Exam I will cover through Chapter 3. Start getting ready now!
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cyclopropane – Angle strain: Angle strain: The C-C-C bond angles are compressed from 109.5° to 60°. – Torsional Torsional strain: strain: There are 6 sets of eclipsed hydrogen interactions. – Strain energy in cyclohexane is about 116 kJ (27.7 kcal)/mol. H H H H H H
Background image of page 2
• Cyclopropane is strained. This reflects that the C-C bond is not sp 3 but more like sp 4 or sp 5 which is worse. • Sometimes people say sp 3 + π bonding. This is the same. C H H C H H C H H This shows up in the fact that: + H 2 Ni (cat.) at 120 o C H 3 CCH 2 CH 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cyclobutane – Puckering from planar cyclobutane reduces torsional strain but increases angle strain. – The conformation of minimum energy is a puckered “butterfly” conformation. – Strain energy is about 110 kJ (26.3 kcal)/mol. (So, not so different from cyclopropane.) – Hydrogenation to n-butane also possible.
Background image of page 4
Cyclopentane – Puckering from planar cyclopentane reduces torsional strain, but increases angle stain. – The conformation of minimum energy is a puckered “envelope” conformation. – Strain energy is about 42 kJ (6.5 kcal)/mol. (No hydrogenation to n-pentane is possible.)
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cyclohexane - Our Main Emphasis Chair conformation: Chair conformation: The most stable puckered conformation of a cyclohexane ring. – all bond C-C-C bond angles are 110.9°. – all bonds on adjacent carbons are staggered.
Background image of page 6
Cyclohexane • In a chair conformation, six H are equatorial and six are axial.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cyclohexane • For cyclohexane, there are two equivalent chair conformations.
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/23/2010 for the course CH 54410 taught by Professor Sessler during the Spring '10 term at University of Texas.

Page1 / 30

Lecture11 F08 given - Lecture 11 Organic Chemistry I Prof....

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online