l Aldehydes and ketones react reversibly with two equivalents of alcohol in the presence of an acid catalyst to give acetals. Alcohols are poor nucleophiles, and so protonation of the carbonyl oxygen is used to make the carbonyl carbon a stronger electrophile. Addition of the first equivalent of alcohol gives a hemiacetal, a hydroxyether. Addition of the second equivalent of alcohol is accompanied by loss of water to yield the product acetal. Draw curved arrows to show the movement of electrons in this step of the mechanism. H₂C 2 CH₂OH HCI catalyst CH3 H3CO OCH3 H3C. CH3

l Aldehydes and ketones react reversibly with two equivalents of alcohol in the presence of an acid catalyst to give acetals. Alcohols are poor nucleophiles, and so protonation of the carbonyl oxygen is used to make the carbonyl carbon a stronger electrophile. Addition of the first equivalent of alcohol gives a hemiacetal, a hydroxyether. Addition of the second equivalent of alcohol is accompanied by loss of water to yield the product acetal. Draw curved arrows to show the movement of electrons in this step of the mechanism. H₂C 2 CH₂OH HCI catalyst CH3 H3CO OCH3 H3C. CH3

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter21: Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution Reactions

Section21.SE: Something Extra

Problem 75AP: One frequently used method for preparing methyl esters is by reaction of carboxylic acids with...

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H3C. H3C. CH3 nnc» XT :OH 2 CH₂OH HCI catalyst Aldehydes and ketones react reversibly with two equivalents of alcohol in the presence of an acid catalyst to give acetals. Alcohols are poor nucleophiles, and so protonation of the carbonyl oxygen is used to make the carbonyl carbon a stronger electrophile. Addition of the first equivalent of alcohol gives a hemiacetal, a hydroxyether. Addition of the second equivalent of alcohol is accompanied by loss of water to yield the product acetal. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions CH3 H3C CH3OH H3CQ OCH3 CH3 H3C. H HO: :OCH 3 CH3 46
H3C 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 CH3
H₂C ཏཱཏི 1 ནི 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 :0: H3C Br Br + :::OH2 Br H₂O H3C Br за
Nonconjugated , -unsaturated ketones, such as 3-cyclohexenone, are in an acid-catalyzed equilibrium with their conjugated , -unsaturated isomers. Propose a mechanism for this isomerization.
One frequently used method for preparing methyl esters is by reaction of carboxylic acids with diazomethane, CH2N2. The reaction occurs in two steps: (l) protonation of diazomethane by the carboxylic acid to yield methyldiazonium ion, CH3N2+, plus a carboxylate ion; and (2) reaction of the carboxylate ion with CH3N2+. (a) Draw two resonance structures of diazomethane, and account for step 1. (b) What kind of reaction occurs in step 2?
A synthetic organic molecule, G, which contains both aldehyde and ether functional groups, is subjected to a series of reactions in a multi-step synthesis pathway. In the first step, G undergoes a Wittig reaction, leading to the formation of an alkene, H. Subsequently, H is treated with an ozone (O3) reagent followed by a reducing agent in an ozonolysis reaction, resulting in the formation of two different products, I and J. Considering the functional groups present in G and the nature of the reactions involved, what are the most probable structures or functional groups present in products I and J? A. I contains a carboxylic acid group, and J contains an aldehyde group. B. I contains a ketone group, and J contains an alcohol group. C. I and J both contain aldehyde groups. D. I contains an ester group, and J contains a ketone group. Don't use chat gpt.
Ketones and aldehydes react with sodium acetylide (the sodium salt of acetylene) to give alcohols, as shown in the following example: R, OH 1. HC=C: Na* 2. Hзо C. R2 R2 HC Draw the structure of the major reaction product when the following compound reacts with sodium acetylide, assuming that the reaction takes preferentially from the Re face of the carbonyl group. Use the wedge/hash bond tools to indicate stereochemistry where it exists. You do not have to explicitly draw H atoms. If a group is achiral, do not use wedged or hashed bonds on it.
Give the major organic product(s) of the following reaction. 1) NABH4 ? 2) H3o+
2 Moin H3C H H₂C C⇒x= base :0: OH Hori H3C H. The aldol reaction is a carbonyl condensation reaction between two carbonyl partners and involves a combination of nucleophilic addition and a-substitution steps. One partner is converted into an enolate ion nucleophile and adds to the electrophilic carbonyl group of the second partner. In the classic aldol reaction, the carbonyl partners are aldehydes or ketones, although aldehydes are more reactive. The product is a B-hydroxy carbonyl compound. Under reaction conditions slightly more vigorous than those employed for the aldol reaction, the ß-hydroxyl group is eliminated in an E1cB dehydration to give an a,ß-unsaturated carbonyl compound. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions H₂C Ἡ :0: heat H Home H3C + H₂O
An alkene is treated with OsO4 followed by H2O2. When the resulting diol is treated with HIO4, the only product obtained is an unsubstituted cyclic ketone with molecular formula C6H10O. What is the structure of the alkene?
HO, но. Chrysanthemic acid Chrysanthemyl alcohol OH H20 TsO. DMSO Chrysanthemyl tosylate Artemesia alcohol Yomogi alcohol Chrysanthemic acid occurs as a mixture of esters in flowers of the chrysanthemum (pyrethrum) family. Reduction of chrysanthemic acid to its alcohol, followed by conversion of the alcohol to its tosylate, gives chrysanthemyl tosylate. Solvolysis of the tosylate gives a mixture of artemesia and yomogi alcohols. Draw curved arrows to show the movement of electrons in this step of the reaction mechanism. Arrow-pushing Instructions HO+ :OH :A H-A
NAC↔X™ Ph Ph OH Acid chlorides react with Grignard reagents to yield tertiary alcohols, two equivalents of Grignard reagent are required. The first equivalent reacts in a typical nucleophilic acyl substitution reaction to give a ketone. This ketone, however, is itself reactive in the Grignard reaction. Thus, the second equivalent adds to the ketone carbonyl carbon. Subsequent protonation yields the tertiary alcohol. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions Ph :0: 1. 2 eq. CH3MgBr 2. H3O+ CH3 H3C CH3 H3C-MgBr Ph O: MgBr -CH3 CH3