Organic Chemistry
8th Edition
ISBN: 9781305580350
Author: William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote
Publisher: Cengage Learning
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Question
Chapter 16, Problem 16.70P
Interpretation Introduction
Interpretation:
The given reaction is
The cyclic hemiacetals formed from D-ribose are four-membered or five-membered or six-membered has to be given.
Concept Introduction:
Cyclic hemiacetals are formed by the intramolecular reaction of a carbonyl group with alcohol group.
Expert Solution & Answer
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Students have asked these similar questions
Ribose, a carbohydrate with the formula shown, forms a cyclic hemiacetal, which, in
principle, could contain either a four-membered, five-membered, or six-membered ring.
When D-ribose is treated with methanol in the presence of an acid catalyst, two cyclic
acetals, A and B, are formed, both with molecular formula C,H,0, These are separated,
and each is treated with sodium periodate (Section 10.8C) followed by dilute aqueous
acid. Both A and B yield the same three products in the same ratios.
он о
CHO
СНО
H+ CH,OH A +B
ÕH
1. NalO,
2. H,0*
НО
CHO + CHOH + CH,OH
ÕH
CH,OH
Isomeric cyclic
acetals with molecular
formula CH12O,
D-Ribose
(C;H1605)
From this information, deduce whether the cyclic hemiacetal formed by D-ribose is four-
membered, five-membered, or six-membered.
Ribose, a carbohydrate with the formula shown, forms a cyclic hemiacetal, which, in principle, could contain either a four-
membered, five-membered, or six-membered ring. To determine which ring is formed, ribose is treated with methanol in the
presence of an acid catalyst. The products are then isolated and treated with NaIO4 then with H3O+.
OH
HO
OH
OH
Ribose, C5H10O5
H
MeOH
H*
A & B
isomeric cyclic
acetals with
formula C6H₁2O5
1. NalO4
2. H₂O*
MeOH products
Assuming that ribose formed a six-membered ring cyclic hemiacetal, draw the structure of the sodium periodate digestion
products.
• Use the wedge/hash bond tools to indicate stereochemistry where it exists.
• Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner.
b) Compounds A and B have the following properties:
Compound A (C5H1005) is an optically active D-pentose that exists exclusively as an acyclic molecule. (Hint:
that sentence alone completely determines the structure of A! But we generously give you more information.)
• Compound A does not react with Br₂/H₂O.
• Reduction of A with NaBH4 gives only one product, B (C5H12O5), which is optically active.
Write acyclic Fischer projection structures of A and B.
Chapter 16 Solutions
Organic Chemistry
Ch. 16.1 - Write the IUPAC name for each compound. Specify...Ch. 16.1 - Write structural formulas for all aldehydes with...Ch. 16.1 - Write the IUPAC name for each compound.Ch. 16.5 - Prob. 16.4PCh. 16.6 - Prob. 16.5PCh. 16.7 - Prob. 16.6PCh. 16.7 - Write a mechanism for the acid-catalyzed...Ch. 16.8 - Prob. 16.8PCh. 16.8 - The given mechanism of transamination reaction is...Ch. 16.8 - The given mechanism of transamination reaction is...
Ch. 16.8 - The given mechanism of transamination reaction is...Ch. 16.8 - Prob. DQCh. 16.8 - Prob. EQCh. 16.8 - The given mechanism of transamination reaction is...Ch. 16.9 - Predict the position of the following equilibrium.Ch. 16.9 - Draw a structural formula for the keto form of...Ch. 16.10 - Prob. 16.11PCh. 16.11 - What aldehyde or ketone gives these alcohols upon...Ch. 16.11 - Prob. 16.13PCh. 16 - Prob. 16.14PCh. 16 - Prob. 16.15PCh. 16 - The infrared spectrum of compound A, C6H12O, shows...Ch. 16 - Following are 1H-NMR spectra for compounds B...Ch. 16 - Draw structural formulas for the product formed by...Ch. 16 - Suggest a synthesis for the following alcohols...Ch. 16 - Show how to synthesize the following alcohol using...Ch. 16 - 1-Phenyl-2-butanol is used in perfumery. Show how...Ch. 16 - Prob. 16.22PCh. 16 - Draw structural formulas for (1) the...Ch. 16 - Show how to bring about the following conversions...Ch. 16 - Prob. 16.25PCh. 16 - Wittig reactions with the following -chloroethers...Ch. 16 - Prob. 16.27PCh. 16 - Prob. 16.28PCh. 16 - 5-Hydroxyhexanal forms a six-membered cyclic...Ch. 16 - Prob. 16.30PCh. 16 - Prob. 16.31PCh. 16 - Propose a mechanism to account for the formation...Ch. 16 - Prob. 16.33PCh. 16 - Prob. 16.34PCh. 16 - Show how to bring about the following conversion.Ch. 16 - A primary or secondary alcohol can be protected by...Ch. 16 - Prob. 16.37PCh. 16 - Prob. 16.38PCh. 16 - Prob. 16.39PCh. 16 - Prob. 16.40PCh. 16 - The following molecule belongs to a class of...Ch. 16 - When cis-2-decalone is dissolved in ether...Ch. 16 - Prob. 16.43PCh. 16 - Prob. 16.44PCh. 16 - The following bicyclic ketone has two -carbons and...Ch. 16 - Propose a mechanism for this reaction.Ch. 16 - The base-promoted rearrangement of an -haloketone...Ch. 16 - If the Favorskii rearrangement of...Ch. 16 - (R)-Pulegone, readily available from pennyroyal...Ch. 16 - (R)-Pulegone is converted to (R)-citronellic acid...Ch. 16 - Starting with cyclohexanone, show how to prepare...Ch. 16 - Show how to convert cyclopentanone to these...Ch. 16 - Prob. 16.53PCh. 16 - Prob. 16.54PCh. 16 - Prob. 16.55PCh. 16 - Following is the structural formula of Surfynol, a...Ch. 16 - Prob. 16.57PCh. 16 - Propose a mechanism for this isomerization.Ch. 16 - Starting with acetylene and 1-bromobutane as the...Ch. 16 - Prob. 16.60PCh. 16 - Prob. 16.61PCh. 16 - Prob. 16.62PCh. 16 - Prob. 16.63PCh. 16 - Prob. 16.64PCh. 16 - All rearrangements we have discussed so far have...Ch. 16 - In dilute aqueous base, (R)-glyceraldehyde is...Ch. 16 - Treatment of -D-glucose with methanol in the...Ch. 16 - Treating a Grignard reagent with carbon dioxide...Ch. 16 - Prob. 16.69PCh. 16 - Prob. 16.70PCh. 16 - Prob. 16.71PCh. 16 - Prob. 16.72PCh. 16 - Write the products of the following sequences of...Ch. 16 - Using your reaction roadmaps as a guide, show how...Ch. 16 - Using your reaction roadmaps as a guide, show how...Ch. 16 - Using your reaction roadmaps as a guide, show how...Ch. 16 - Using your reaction roadmaps as a guide, show how...Ch. 16 - Prob. 16.78PCh. 16 - Prob. 16.79PCh. 16 - Prob. 16.80PCh. 16 - Prob. 16.81P
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