aldehyde and ketone has C=O which is very much polarised and are reactive towards nucleophilic addition reaction. But if we expect nucleophilic substitution from enolate form of aldehyde or ketone this is not spontaneous as pKa values of those enolate ions generally above 15 (except ethyl acetoacetate, acetylacetone etc.)
Q3. Explain why the reaction of aldehydes & ketones is. nucleophilic addition. Use pka values in...
Draw a general curved arrow mechanism for nucleophilic addition of aldehydes and ketones. OH Nus RA'R' / H2O+ R Nu Content Clue: Aldehydes and ketones react with various nucleophiles that can be based on carbon, hydrogen, nitrogen and oxygen. Carbon-based nucleophiles include: Grignard reagents, cyanide anion, and Wittig reagents. Grignard reagents as nucleophiles: 1) MgBr 2) H30+ 1) CH 3MgBr 2) H30+ 2 stereoisomers formed State the stereochemical relationship between products: MgBr 2. H3O+
Draw a general curved arrow mechanism for nucleophilic addition of aldehydes and ketones. OH Nus RA'R' / H2O+ R Nu Content Clue: Aldehydes and ketones react with various nucleophiles that can be based on carbon, hydrogen, nitrogen and oxygen. Carbon-based nucleophiles include: Grignard reagents, cyanide anion, and Wittig reagents. Grignard reagents as nucleophiles: 1) MgBr 2) H30+ 1) CH 3MgBr 2) H30+ 2 stereoisomers formed State the stereochemical relationship between products: MgBr 2. H3O+
one and two 1. Aldehydes are more susceptible to nucleophilic attack than ketones. Explain. 2. Complete the following reaction scheme. РОCЬ pyridine 1. O3 NaBH 2. Me S E1OH (CH3)2CuLi SOC/2 H30*, heat 1. LIAIH NaCN Br 1. DIBALH acetone 2. Hа0 2. H30* 1. DIBALH 2. H30* HCN
Nucleophilic addition to aldehydes and ketones Examples: Que. 6) What is the major organic product obtained from the following reaction? Note that Et20 is acting as solvent, CHO 1. (CH3)2CHCH2MgBr Et20 2. H3O+ a. 2,3-dimethyl-3-heptanol b. 2,4-dimethyl-4-heptanol C. 3,5-dimethyl-4-heptanol d. 3,5-dimethyl-3-heptanol Que. 7) Which combination(s) of alkyl bromide and carbonyl compound can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the carbonyl compound? OH CH3BT CH3CH2CH2Br CH3CH2Br (CH3)2CHBO a...
3) Draw resonance diagrams to explain why phenol has a pka pf 10 whereas aliphatic alcohols like ethanol have a pka of 16. 4) Why are aldehydes generally more reactive towards nucleophilic attack than ketones? 5) Suggest possible steps involved in the synthesis of the following compound starting propene. Note for each step involved your desired product must be a major product. Also note the two arrows indicate an unknown number of steps are involved.
9) 9) Why do aldehydes undergo nucleophilic addition reactions, whereas esters undergo nucleophilic acyl substitution reactions? A) The carbonyl carbon of an ester is more electrophilic than that of an aldehyde. B) Once the nucleophile adds to an aldehyde, neither H- nor R-can be eliminated because they are strongly basic. C) Aldehydes are more sterically hindered than esters. D) The ester carbonyl carbon is sp3 hybridized while the aldehyde carbonyl carbon is sp2 hybridized. E) Once the nucleophile adds to...
9. Reactions involving Enolates Ketones E) B-dicarbonyl Aldol: best with aldehydes Aldol addition Hproduct t冫 Aldol condensatiorn product Claisen Reaction: Esters! 9. Reactions involving Enolates Ketones E) B-dicarbonyl Aldol: best with aldehydes Aldol addition Hproduct t冫 Aldol condensatiorn product Claisen Reaction: Esters!
Explain why aldehydes and ketones have a higher boiling point than the corresponding hydrocarbons.
2. Give IUPAC names for the following compounds. 3. Name methods to prepare ketones and aldehydes from alcohols. Give the reagents. 4. Show the mechanism for the acid and base promoted nucleophilic addition reactions. Start from the carbonyl of your choice. Use NaOH as the base and HCI- as the acid. -
Please explain using Aldehydes and Ketones terms! Chem 202, Autumn 2019 Homework Packet 10 (Aldehydes and Ketones) 2. Reactivity of Aldehydes and Ketones a. Rank the following aldehydes and ketones in order from LEAST reactive to MOST reactive: H Н Н Н А В b. Justify your answer thoroughly in words: ш