Ketones and Aldehydes in Organic Chemistry II - Study Guide | CHEM 3332, Study notes of Organic Chemistry

Download Ketones and Aldehydes in Organic Chemistry II - Study Guide | CHEM 3332 and more Study notes Organic Chemistry in PDF only on Docsity! CHAPTER 18: KETONES AND ALDEHYDES Carbonyl compounds: reagents / solvents / and constituent: Bean Chem 3332 's of fabrics / flavorings / plastics / drugs / proteins / carbohydrates / nucleic acids ° oO fe} oO oO oO ul I il il I u R—-C—R R-C—H R—C—OH R-—C—cl R—C—oR R—C —NHp |. Structure: ° ° ° I «> c c ano Na CHy~ HCH CH CHO Hy CHgCH,-O—H Il. Physical Properties: A. Boiling Point 9 9 I CHgCHyCH2CHg =» CH3—O—CH2CHy =~ CHyCH» —C —H CH, —C —CHg CHgCH,CH2-O—H B. Solubility -O~, ° 4 4 ° G AW am CHs~ CH ili. Reactivity: A. Acidity of Alhpa Hydrogens Hoo lou $B° R-C—C—R —, | H B. Reactivity of Aldehyde vs Ketone IV. Aldehyde and Ketone Nomenclature: A. As parent: (priority over alcohols, amines, alkenes, alkynes, ethers) 1. Aldehydes - drop “e" from alkane, add "al" Oo a Q CHgCH,CH,-C-H CH CH-CHy-CH-CH CH,CH2CHs Oo HO-CH,CH CH CH>-C+H For cyclic aldehydes: add "carbaldehyde" cr or “CH, CHs 2. Ketones - drop "e" from alkane name, add "one" CH Cl aN A ry? 7 2 OH b= CH3CH-CH5-CH-C-CH2CH, CHy OCHS CH-C-CH, CH, For cyclic ketones: since carbonyl is part of ring, same as acyclic ketones; carbonyl is always # 1 ° OH B. As substituents: CH ° jo CH “formyl” COH 9 HC "oxo" Cyc OH VI. Aldehyde and Ketone Synthesis: (A-D are Review) A. Oxidation of Alcohols 1° alcohol oop aldehyde 2° alcohol PCC ketone or Jones’ ox or NagCraO7/H2SO4/H20 B. Cleavage of Alkenes by Ozonolysis CHs CHg \ / 1.03 CHs hs an 2, (CHg)o5 ao + O=c. H CHg H ‘CH, C. Friedel-Crafts Acylation oO RC.) 9 —C- il ——_—— C-R AICly 9 COMC! _ (> AICk/cucl Cp H No strong deactivators on ring (halogens OK) No amino groups on ring D. Hydration of Alkynes R MM oO H. B— CECH on aoe on ~— R—C-CH, HO H 1. SiagBH 2, HpOo/NaOH R H No o” 9 yo — R-CH,—C-H H ‘OH ith . R—C==c—pR SMelteagent mixture of ketones E. 1, 3 - Dithiane Synthesis of Aldehydes and Ketones a multi-step synthesis: eo CH9(CHp)9CHp - Li $s s rs wn or Cy ui eo s + R-X ——. ae H ce ) 8 CH3(CHp)oCHp - Li Li or Cr n on x = a s s + R—-X ——» aX R Example: oO ll CH;CH,—C -o< ) F. Ketones from Carboxylic Acids a multi-step synthesis oO it” 1. R—C—O-H it “OH, o R'—Li I 2. R-C—OLi*t ——. Ott I + 3 R—C—OL _H30" R' Example: o . Cheb —on 1. CHgCH2CHprLi (2 69.) 2 Hg0* G. Ketones from Nitriles R-C=N + R'—MgX = ——» Example: MgBr CHa-C=N + CY ether 1) 1. Grignard Reaction: 9 Ty too i \ —c—p- 20-1 —cC—pR Cw, + RiMgX I~ R ¢ R R—C—R R R | R ° RETR R 2. Addition of Acetylide: 9 ° How | on u" — . DFr| — 1 ao + NaC=CR' A—G-C=CR R—C-—C=C-R R R 3. Addition of Hydride: 9 + OH R—E—-H —— =R-C-H R “ong + Lit H-AIH3 4. Catalytic Hydrogenation: similar to hydrogenation of alkenes, but aldehydes and ketones are less reactive Oo CL Cy 4 He, Raney Ni 2 Raney 5. Hydration: a. The reaction Oo a a’ OnR + HO = 0 W ao OTH + HO = b. Position of EQ depends on the structure of the aldehyde or ketone: 0 in —_— CL + HO ==> H3C~ CHg 2 g a7 OoH + HzO =~— g cue’ OH + 40 == 3 How to predict EQ? - the more stable the aldehyde or ketone, the more the EQ lies to the aldehyde or ketone, not the hydrate - the less positive the carbonyl carbon, the more stable the aldehyde or ketone Oo Oo Oo oO C R~ R c. Reaction Rate and Catalysis 1) acid catalyst il 2) base catalyst 2 C “O-H R~ ~R 6. Addition of HCN Q Cc + H-CN == R~ ~R 2 a CL, + H-CN [= Mechanism: 2 ceN 2s Oo R Example: 9° NaCN /Ht ed CHsCH,~ —~H 7. Addition of Amines a. 1° amines: oO + C + RNH, 10H “an i2 Mechanism of Enamine Formation: gt et i | R—-C—C— + RAH == RCC — NR, H7+ > H H H SO + I | I R—-C—Cc— == R—-C—C— 14 NRo NRo i R'—C—cC— I ot +NRo {| HzO RY \ cH” 7 \ RoN Example: oO I + CHg-C-CHaCHg + (CHg)oNH wy 8. Addition of Alcohols (Acetal Formation) + om A—C—C— rt NR, 7+” | Hz0 mt fj R'—C—C— 1 Np is 16 Example: ° CH C-cH H* aee"S 2 CHgCHzQH = > Mechanism: H ° to7 O-H . OH ll Ht I ROH i VR Bs R t o-R = Cc —— R-C—O+ —_— uO R~ “R R” “rR A Nu R | | Hw Ho+ R OH OR \ 1 UR ROH c=0. ~<~— >» R-C—O—R === =R-C-—O-R R-C-0O+ ~ / 1 1 I XN R A R R R H | jes OR I R-C—O-—R I R Acetals are "protected carbonyls": +2ROH carbonyl) = acetal + H20 -2 ROH Example: oO i] oO C-OCH, 4 oO CH,OH Mechanism of deprotection is the reverse of acetal formation. Remember the hydrolysis below? R HS SH RR Similar: H,0t 9 oO. LO HgClp A. + HO. OH 4 RR RR i Selective Acetal Formation - alcohols are weak nucleophiles, therefore selective nucleophiles - aldehydes are more reactive than ketones, therefore alcohols selectively react with aldehydes to form acetals in the presence of ketones