Quiz_4_KEY

Quiz_4_KEY - Chemistry 140C (Finn) Spring 2008 Quiz 4 This...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chemistry 140C (Finn) – Spring 2008 – Quiz 4 This quiz is for extra credit , as usual, worth a maximum of 40 points. Name: KEY (1) (10 points) Rank the heterocycles below in order of acidity. Place a “1” in the box under the most acidic compound, a “2” under the second most acidic, and a “3” under the weakest acid. N N N H N N H N N N H N imidazole 1,2,3-triazole tetrazole 3 2 1 Rationale: deprotonation of each gives anions that can distribute the charge to each position of the ring. (See the discussion in the book about the acidity of pyrrole.) The more nitrogen atoms in the ring, the more of those resonance forms put a negative charge pK a = 14.4 pK a = 9.3 pK a = 4.9 on an electronegative atom. Z N Z H N H + Z N Z N Z = N or CH Z N Z N Z N Z N Z N Z N Z N Z N (2) (30 points) The one-pot reaction of an aldehyde ( 1 ), a ! -keto ester ( 2 ), and an amidine ( 3 , looks something like a guanidine group that you would find on the amino acid arginine) gives molecule 4 (shorthand name: a dihydropyrimidine). On
Background image of page 1

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

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 06/07/2008 for the course CHEM 140C taught by Professor Nefzi during the Spring '06 term at UCSD.

Page1 / 2

Quiz_4_KEY - Chemistry 140C (Finn) Spring 2008 Quiz 4 This...

This preview shows document pages 1 - 2. Sign up to view the full document.

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