University:
Kentucky State University
Course:
CHE 302 | Organic Chemistry II
Academic year:

2020
Views:

31

Pages:

7
Author:

strofamay52

**Boiling Point:** **1. Number of Carbon Atoms:** * More carbon atoms = higher boiling points * CH₃CH₂CH₃ bp: 0°C * CH₃CH₂CH₂CH₃ bp: -0.5°C * CH₃CH₂CH₂CH₂CH₃ bp: 36°C **2. Branching:** * More branching = lower boiling point **n-pentane** H-C-C-C-C-H | | | | | H H H H H isopentane H H H | | | H-C-C-C-H | | H H neopentane H | H-C-C-H | | | H H H Draw C₅H₁₂ with the lowest boiling point isomer: H | H-C-C-H | | | H H H C₅H₁₂ with the lowest boiling point 2. Conformations of Alkanes: Conformations are isomers which are resulting from the rotation of the (C-C) single bond around itself. We will study 2 main conformations: Eclipsed: H's facing each other directly. H H | | H-C-C-H | | H H Staggered: H's are the furthest away from another. H H \ / H-C-C-H / \ H H **Newman Structure** * **How to study conformations:** 1. Assign the C-C bond to study. 2. Put your eye on a carbon of the C-C bond. 3. The orientation should be parallel to the C-C bond. 4. Draw Newman-structure. **Draw:** C₂H₆ H H \ / H-C-C-H / H H **Eclipsed:** H H | | H-C-C-H | | H H **Staggered:** H H \ / H-C-C-H / H H * **The angle is 0°** * **Less stable** * **Higher energy** * **The angle is 60°** * **More stable** * **Less energy** This is caused by the repulsive interactions between the C-H single bonds' electrons. **Torsional strain:** (between bonded e-) * **Most torsional strain:** eclipsed conformation * **Zero torsional strain:** staggered conformation