feb_24 - 2/25/2010 These type of reactions are catalyzed by...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 2/25/2010 These type of reactions are catalyzed by both acid and base. What is the mechanism of the acid catalyzed reaction? H H H O H O H O H O H -H H H H O H O H H H These type of reactions are catalyzed by both acid and base. What is the mechanism of the acid catalyzed reaction? H H H O H O H O H O H -H H H or OH H O H O H H H more reactive C=O H +H H more reactive C=O H +H H O + H H H O O + H H H O What is the first intermediate in this mechanism? O H H O H H O H OH H more reactive nucleophile OH HO H O H H O H H A B H What is the mechanism of the base catalyzed reaction? What is the first step? C There are two forms of formaldehyde in water, the carbonyl compound and its hydrate. In water the hydrate is the dominant form. Keq O + H H H O H H O H O H H H O + H H O H H O H O H H 2000 formaldehyde formaldehyde E ∆G˚ = -RTlnKeq R Would the Keq of acetaldehyde be (A) larger or (B) smaller or (C) the same as formaldehyde? Keq O H H + C H H H O H H H H O C H O H H O H H C H H H H What is the best reason why acetaldehyde is less hydrated than formaldehyde? Keq O + C H H H O H H H H O C H O H H 1.3 acetaldehyde O + H H H O H H O H O H H 2000 H O + H H O H H O H O H H 2000 formaldehyde A. A. The methyl group stabilizes the hydrated form. B. The methyl group stabilizes the C=O group. C. Formaldehyde is not soluble in water. D. Acetaldehyde is not soluble in water. E ∆G˚ = -RTlnKeq R 1 2/25/2010 Would the Keq of acetaldehyde be (A) larger or Would (B) smaller or (C) the same as acetone? Keq O H H + C H H H O H H H H O C H O H H Would the Keq of acetaldehyde be (A) larger or Would (B) smaller or (C) the same as acetone? Keq O H H + C H H H O H H H H O C H O H H 1.3 1.3 acetaldehyde acetaldehyde O H H C H C H H H + H O H H H H O C H O C H H H H H H C H O C H H H + H O H H H H O C H O C H H H H 0.002 acetone acetone Would the Keq of acetaldehyde be (A) larger or Would (B) smaller than trichloroacetaldehyde? Keq O H H + C H H H O H H H H O C H O H H Would the Keq of trichloroacetaldehyde be (A) larger or (B) smaller than acetaldehyde? Keq O H H + C H H H O H H H H O C H O H H 1.3 1.3 acetaldehyde acetaldehyde O Cl Cl C Cl O Cl Cl + C Cl H H O H H acetaldehyde O Cl Cl C Cl O Cl Cl + C Cl H H O H H H Cl Cl O C Cl O H H H Cl Cl O C Cl O H H 2000 trichloroacetaldehyde trichloroacetaldehyde Do alcohols react with carbonyl compounds? Which compound is behaving as the acid? Which arrow is correct? A B H O O H CH3 H O H O CH3 Which of the following is an intermediate on A going from the hemiacetal to the acetal? H O O H H CH3 B H O CH3 O CH3 O H H C H O H H O H O O +H CH3 C ketone H H O H3C O O CH3 CH3 hemiacetal CH3 H3C H O + H H H O O CH3 H O O CH3 O CH3 H H O H3C O O CH3 ? acetal acetal 2 2/25/2010 What are acetals and hemiacetals? hemiacetals? Predict the product of the reaction of water with cyclohexanone in the presence of an acid catalyst. H H O O H CH3 O O +H CH3 H O H CH3 H3C O O CH3 O + H O CH3 H H3C O O + H2O CH3 ketone hemiacetal acetal ketone acetal E R Predict the product of the reaction of water with cyclohexanone in the presence of an acid catalyst. What is the major product of the following reaction? H3C O + H O CH3 H O O CH3 OH OH ketone acetal H O OH O OH2 E R A B C D What is the mechanism of the following reaction? Choose the structure that is an intermediate in the following reaction? H H O A B C D 3 2/25/2010 How many acetals and hemiacetals are present in the carbohydrate lactose? H O O +H CH3 H3C O O + CH3 H2O Acetals and ketals can be used to protect carbonyl groups. hemiacetal HO HO O HO HO O OH O OH lactose OH OH H O OH HO OH H HO O OH acetal O HO H H O H HO CH3 O O +H CH3 H3C O O + CH3 H2O O HO OH OH glucose glucose A acetal hemiacetal 1 0 B 1 1 C 0 1 D 0 0 E 2 0 F 2 1 Acetals and ketals can be used to protect carbonyl groups. How could the following transformation be accomplished? H3C O H H / H2O O O CH3 O 1. 2. H3O OH No Reaction 1. MeOH/H 2. LiAlH4 3. H3O Li 1. 2. H3O Li O NaBH4 MeOH OCH3 O OH H OCH3 1. MeOH/H 2. NaBH4 3. H3O NaBH4 MeOH A B C D How could the following transformation be accomplished? How could the following transformation be accomplished? O O O MeOH/H OCH3 OCH3 LiAlH4 OCH3 OCH3 H3O O O OCH3 H H OH O OCH3 O OCH3 H H O H H OH 1. MeOH/H 2. LiAlH4 3. H3O 1. MeOH/H 2. NaBH4 3. H3O NaBH4 MeOH 1. LiAlH4 2. H3O 1. MeOH/H 2. LiAlH4 3. H3O 1. MeOH/H 2. NaBH4 3. H3O NaBH4 MeOH 1. LiAlH4 2. H3O A B C D A B C D 4 2/25/2010 5 ...
View Full Document

This note was uploaded on 04/06/2010 for the course CHE 326 taught by Professor Fowler during the Spring '08 term at SUNY Stony Brook.

Ask a homework question - tutors are online