Chapter%2020%20-%20complete%20notes

Chapter%2020%20-%20complete%20notes - Chapter 20 Carboxylic...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 20 – Carboxylic Acid Derivatives Instructor: Dr. Daniel Seidel Carboxylic acid derivatives undergo substitution reactions via the (often acid- or base-catalyzed) addition-elimination sequence:
Background image of page 1

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

View Full DocumentRight Arrow Icon
Background image of page 2
Resonance in Carboxylic Acid Derivatives Lone pairs on L can be delocalized onto the carbonyl oxygen: The rightmost resonance form is most important in amides and somewhat less important in esters. Amides and esters are strongly stabilized by resonance. Anhydrides are more reactive than esters because the lone pairs on the central oxygen are shared over two carbonyl groups. Acid halides are least stable because of their electro negativity and the poor overlap between their p- orbitals and those of carbon.
Background image of page 3

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

View Full DocumentRight Arrow Icon
Resonance in Carboxylic Acid Derivatives The greater the resonance, the shorter the C-L bond. The structures of carboxylic acid derivatives are directly related to the extent of resonance. In progressing from alkanoyl halides to esters and amides, the C-L bond becomes progressively shorter (increased double bond character).
Background image of page 4
The NMR spectra of N,N-dimethylformamide at room temperature exhibit two signals for the two methyl groups. Bond rotation about the C-N bond in this molecule is very slow on the NMR time scale. The measured barrier to this rotation is about 21 kcal mol -1 . The amide nitrogen possesses sp 2 hybridization. The resultant planarity of the amide
Background image of page 5

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

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 06/25/2009 for the course CHEM 01:160:308 taught by Professor Bokiess during the Spring '09 term at Rutgers.

Page1 / 34

Chapter%2020%20-%20complete%20notes - Chapter 20 Carboxylic...

This preview shows document pages 1 - 6. Sign up to view the full document.

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