ORGANIC CHEMISTRY MASTERINGCHEM ACCESS
9th Edition
ISBN: 9780137249442
Author: Wade
Publisher: INTER PEAR
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Textbook Question
Chapter 18, Problem 18.41SP
Acetals can serve as protecting groups for 1,2-
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Br2, H3O+
གོ་ཤི་ན་ཤི་
H3C CH3
CH3
CH3
Aldehydes and ketones can be halogenated at their a-position by reaction with Cl₂, Br2, or 12, under acidic conditions. Using Br2 under acidic conditions, an intermediate enol is formed which adds
bromine at the a-position. The reaction stops after the addition of one bromine because the electron-withdrawing halogen decreases the basicity of the carbonyl oxygen, making the protonation less
favorable.
Draw curved arrows to show the movement of electrons in this step of the mechanism.
Arrow-pushing Instructions
:OH
:OH
Br-Br
H3C
H3C.
Br
Br
CH₂
H₂
H3C CH3
H3C CH3
2b
CH3
གོན་ནི། ཡོན་
Br₂,
H₂C
CH₂Br
H3C CH3
H₂C CH3
Aldehydes and ketones can be halogenated at their a-position by reaction with Cl₂, Br2, or 12, under acidic conditions. Using Br₂ under acidic conditions, an intermediate enol is formed which adds
bromine at the a-position. The reaction stops after the addition of one bromine because the electron-withdrawing halogen decreases the basicity of the carbonyl oxygen, making the protonation less
favorable.
Draw curved arrows to show the movement of electrons in this step of the mechanism.
Arrow-pushing Instructions
:0:
:OH
н-он
H-OH₂
H₂O
H₂C.
H3C.
CH3
CH3
H3C CH3
H3C CH3
Σα
Some alcohols undergo rearrangement or other unwanted side reactions when they dehydrate in acid. Alcohols may be dehydrated under mildly basic conditions using phosphorus oxychloride (POCl3) in pyridine. The alcohol reacts with phosphorus oxychloride much like it reacts with tosyl chloride, displacing a chloride ion from phosphorus to give an alkyl dichlorophosphate ester. The dichlorophosphate group is an outstanding leaving group. Pyridine reacts as a base with the dichlorophosphate ester to give an E2 elimination. Propose a mechanism for the dehydration of cyclohexanol by POCl3 in pyridine.
Chapter 18 Solutions
ORGANIC CHEMISTRY MASTERINGCHEM ACCESS
Ch. 18.3 - Give the IUPAC name and (if possible) a common...Ch. 18.5D - NMR spectra for two compounds are given here,...Ch. 18.5D - Why were no products from the McLafferty...Ch. 18.5D - Use equations to show the fragmentation leading to...Ch. 18.5E - Prob. 18.5PCh. 18.7D - Show how you would synthesize each compound from...Ch. 18.8 - Prob. 18.7PCh. 18.9 - Predict the products of the following reactions....Ch. 18.9 - Show how the following transformations may be...Ch. 18.10 - Prob. 18.10P
Ch. 18.11 - Show how you would accomplish the following...Ch. 18.11 - Prob. 18.12PCh. 18.12 - Propose mechanisms for a. the acid-catalyzed...Ch. 18.12 - Rank the following compounds in order of...Ch. 18.13 - Prob. 18.15PCh. 18.13 - Show how you would accomplish the following...Ch. 18.14 - Prob. 18.17PCh. 18.14 - Prob. 18.18PCh. 18.14 - Prob. 18.19PCh. 18.14 - Prob. 18.20PCh. 18.15 - 2,4-Dinitrophenylhydrazine is frequently used for...Ch. 18.15 - Prob. 18.22PCh. 18.15 - Prob. 18.23PCh. 18.16 - Prob. 18.24PCh. 18.16 - Prob. 18.25PCh. 18.16 - Show what alcohols and carbonyl compounds give the...Ch. 18.16 - In the mechanism for acetal hydrolysis shown, the...Ch. 18.16 - Prob. 18.28PCh. 18.17 - Show how you would accomplish the following...Ch. 18.18 - Prob. 18.30PCh. 18.18 - Prob. 18.31PCh. 18.18 - Prob. 18.32PCh. 18.18 - Show how Wittig reactions might be used to...Ch. 18.19 - Predict the major products of the following...Ch. 18.20C - Prob. 18.35PCh. 18.20C - Predict the major products of the following...Ch. 18 - Draw structures of the following derivatives. a....Ch. 18 - Prob. 18.38SPCh. 18 - Predict the major products of the following...Ch. 18 - Rank the following carbonyl compounds in order of...Ch. 18 - Acetals can serve as protecting groups for...Ch. 18 - Sketch the expected proton NMR spectrum of...Ch. 18 - A compound of formula C6H10O2 shows only two...Ch. 18 - The proton NMR spectrum of a compound of formula...Ch. 18 - The following compounds undergo McLafferty...Ch. 18 - An unknown compound gives a molecular ion of m/z...Ch. 18 - Show how you would accomplish the following...Ch. 18 - Prob. 18.48SPCh. 18 - Prob. 18.49SPCh. 18 - Propose mechanisms for the following reactions.Ch. 18 - Show how you would accomplish the following...Ch. 18 - Show how you would synthesize the following...Ch. 18 - Predict the products formed when cyclohexanone...Ch. 18 - Predict the products formed when...Ch. 18 - Show how you would synthesize octan-2-one from...Ch. 18 - Prob. 18.56SPCh. 18 - Both NaBH4 and NaBD4 are commercially available,...Ch. 18 - When LiAIH4 reduces 3-methylcyclopentanone, the...Ch. 18 - Prob. 18.59SPCh. 18 - Show how you would accomplish the following...Ch. 18 - There are three dioxane isomers 1,2-dioxane,...Ch. 18 - Two structures for the sugar glucose are shown on...Ch. 18 - Prob. 18.63SPCh. 18 - Prob. 18.64SPCh. 18 - Prob. 18.65SPCh. 18 - Prob. 18.66SPCh. 18 - Within each set of structures, indicate which will...Ch. 18 - Prob. 18.68SPCh. 18 - Prob. 18.69SPCh. 18 - Prob. 18.70SPCh. 18 - The UV spectrum of an unknown compound shows...Ch. 18 - a. Simple aminoacetals hydrolyze quickly and...Ch. 18 - The mass spectrum of unknown compound A shows a...Ch. 18 - Prob. 18.74SPCh. 18 - Prob. 18.75SPCh. 18 - Prob. 18.76SPCh. 18 - Prob. 18.77SP
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- Wittig reactions with the following -chloroethers can be used for the synthesis of aldehydes and ketones. (a) Draw the structure of the triphenylphosphonium salt and Wittig reagent formed from each chloroether. (b) Draw the structural formula of the product formed by treating each Wittig reagent with cyclopentanone. Note that the functional group is an enol ether or, alternatively, a vinyl ether. (c) Draw the structural formula of the product formed on acid-catalyzed hydrolysis of each enol ether from part (b).arrow_forwardTertiary alcohols with two identical alkyl groups attached to the alcohol carbon can be made either from an ester and two moles of a Grignard reagent, or from a ketone and one mole of a Grignard reagent. Use retrosynthetic analysis to suggest one path of each type to synthesize 2-methyl-2-butanol (or 2-methylbutan-2-ol). OH H,O* Reagent 1 + Reagent 2 Route 1: Select an Ester, and an appropriate Grignard, , to give 2-methyl-2-butanol (or 2-methylbutan-2-ol) after reaction and an aqueous workup. Route 2: Select a ketone, , and an appropriate Grignard, to give 2-methyl-2-butanol (or 2-methylbutan-2-ol) after reaction and an aqueous workup. about us privacy policy terms of use contact us help careersarrow_forwardH3C OH 1. Br2, PBг3 2. H₂O H3C OH Br The a-bromination of carbonyl compounds by Br₂ in acetic acid is limited to aldehydes and ketones because acids, esters, and amides don't enolize to a sufficient extent. Carboxylic acids, however, can be a-brominated by first converting the carboxylic acid to an acid bromide by treatment with PBr3. Following enolization of the acid bromide, Br2 reacts in an a-substitution reaction. Hydrolysis of the acid bromide completes the reaction. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions Br Br зь P-Br Br H₂C H₂C SH Br Brarrow_forward
- Write a mechanism that accounts for the formation of ethyl isopropyl ether as one of the products in the following reaction. CI OEt HCI EtOH Write the mechanism for step one of this reaction. Show lone pairs and formal charges. Only the acidic hydrogen should be drawn out with a covalent bond. Write the mechanism for step two of this reaction (where the product of step one reacts with the solvent, ethanol). Show lone pairs and formal charges. Only the acidic hydrogen should be drawn out with a covalent bond. Write the mechanism for the last step of this reaction (formation of ethyl isopropyl ether). Show lone pairs and formal charges. Only the acidic hydrogen should be drawn out with a covalent bond. CI will act as the base in this reaction.arrow_forwardPhenols (pKa ≈ 10) are more acidic than other alcohols, so they are easily deprotonated bysodium hydroxide or potassium hydroxide. The anions of phenols (phenoxide ions) can beused in the Williamson ether synthesis, especially with very reactive alkylating reagents suchas dimethyl sulfate. Using phenol, dimethyl sulfate, and other necessary reagents, show howyou would synthesize methyl phenyl ether.arrow_forwardWhen 2-bromo-2-methylbutane is treated with a base, a mixture of 2-methyl-2-butene and 2-methyl-1- butene is produced. When potassium hydroxide is the base, 2-methyl-1-butene accounts for 45% of the product mixture. However, when potassium tert-butoxide is the base, 2-methyl-1-butene accounts for 70% of the product mixture. What percent of 2-methyl-1-butene would be in the mixture if potassium propoxide were the base? base Br A. Less than 45% B. C. 45% Between 45% and 70% D. More than 70%arrow_forward
- Convert 2-pentanol into 2,3-dibromopentane. Draw structures of the starting material (2-pentanol) and final product (2,3-dibromopentane), and show the two reactions needed for this synthesis. Include the structure of the intermediate compound, and the reagents and conditions for each reaction. Then explain why 1,2-dibromopentane would not be a significant product of this synthesis.arrow_forward1. Br₂, PBrg 2. H₂O H₂C OH H3C OH Br The a-bromination of carbonyl compounds by Br₂ in acetic acid is limited to aldehydes and ketones because acids, esters, and amides don't enolize to a sufficient extent. Carboxylic acids, however, can be a-brominated by first converting the carboxylic acid to an acid bromide by treatment with PBr3. Following enolization of the acid bromide, Br₂ reacts in an α- substitution reaction. Hydrolysis of the acid bromide completes the reaction. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions H3C :0: :0::Br: Br Br H3C CO-P H Br Brarrow_forward! Which are the products of the Cannizzaro reaction * Carboxylic acid and ketone Carboxylic acid and aldehyde Carboxylic acid and alcohol Carboxylic acid Reaction between formaldehyde and benzaldehyde give 1 t Formic acid and methyl alcohol Benzyl alcohol and formic acid Benzyl alcohol and benzoic acid Benzyl alcohol and acetic acid Claisen-Schmidt including reaction between 2 mole of aldehyde not containing a-hydrogen 2 mole of aldehyde containing a-hydrogen 1mole of aldehyde containing a-hydrogen and 1mole of acid containing a-hydrogen 1 mole of aldehyde containing a-hydrogen and other aldehyde not containing a- hydrogen ntarrow_forward
- Show the mecanism for the protection of the diol by forming an acetal with acetone. Remember this reaction occurs in an acidic environment CH3 CH3 с H D CH,COCH; tocamobor CH3 Н.С. OH B 10 11arrow_forwardDraw the structural formula of the enol formed in the following alkyne hydration reaction and then draw the structural formula of the carbonyl compound with which this enol is in equilibrium.arrow_forwardH3C OH OH H+ CH3 Esters can be synthesized by an acid-catalyzed nucleophilic acyl substitution between an alcohol and a carboxylic acid; this process is called the Fischer esterification reaction. Because the alcohol oxygen is a poor nucleophile, the carbonyl carbon is made a better electrophile by protonation of the carbonyl oxygen. The steps of the synthesis are all reversible. The reaction is generally driven to completion by using an excess of the liquid alcohol as a solvent, or by distilling off the product as it forms. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions CIX 10-4 H₂O CH3 H₂O CH3arrow_forward
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