4. Hemiacetals are the product of a reaction between an aldehyde and one equivalent of alcohol. Similarly, hemiketals form by a reaction between a ketone and one equivalent of alcohol. The reaction can be either inter- or intramolecular. The general structures are: 4.1 Complete the following reaction with the corresponding Hemiacetal/Hemiketal. O H3C H OH olanlarson CH3 + H3C H + OH CH3CH₂OH H + CH3OH CH₂OCH3 4.2 Identify the aldehyde and alcohol that will form the following products. OH HOR¹ R hemiacetal هم H3C HO OH R3 OH OR¹ 4.3 Write a complete arrow-pushing mechanism for the following hemiacetal formation under acid- catalyzed conditions. Use H-A to represent the acid catalyst. R hemiketal ܐ ܗ ܙ ܗ >

Choose the reagent(s) from the list at right and give the number of equivalents required. Draw out the R group of the reagent needed. Draw the by-products of the reaction. 26. 27. H C-C Bond Forming Reagents: 1) R-MgBr 2) H3O*CH 1) R-Li 2) H₂O*CI 1) R-CH₂X, PPh3, 2) n-BuLi 1) (EtO)2P(=O)CH₂EWG, 2) NaH CO₂Et

! 11:50 %0AONO propanoic acid can be prepared from reaction with EtONa, CH3-Br And H3O+, heat / -CO2 diethyl malonate ethyl acetoacetate diethyl acetate ethyl acetate i CH₂ a) CH₂-C-PPh a d b) CH₂-C-P CH₂ CH₂-C-C-CH₂ CH₂ CH₂ CH, CH CH₂ O d) CH₂ CH₂ CH₂ C-Phy CH₂

12.27 Assign an IUPAC name for each of the following compounds: HO. OH (b) OH OH (c) 'Br (d)