BAI 1 ALDEHYDE VA KETONES ppt

HOÁ HỮU CƠ BÀI ALDEHYDES & KETONES ALDEHYDE & KETONES CẤU TẠO & LIÊN KẾT TÍNH CHẤT HOÁ HỌC DANH PHÁP ĐIỀU CHẾ TÍNH CHẤT VẬT LÝ ỨNG DỤNG CẤU TẠO VÀ LIÊN KẾT (Structure and Bonding) CẤU TẠO & LIÊN KẾT (Structure and Bonding) CẤU TẠO & LIÊN KẾT (Structure and Bonding) NHÓM CARBONYL (The Carbonyl Group, C=O) Aldehydes Ketones O R C H Ít nguyên tử H liên kết với C nhóm C=O) O C O R C R' C nhóm C=O liên kết với 02 nhóm alkyl CẤU TẠO & LIÊN KẾT (Structure and Bonding) Aldehydes HH2 CC OO formaldehyde formaldehyde OO CH CH3 CH CH Ketones OO CC HH acetaldehyde acetaldehyde benzaldehyde benzaldehyde OO CH CH33CC CH CH33 acetone acetone CH CH33 CH CH33CH CH22CC OO methyl methylethyl ethylketone ketone CẤU TẠO (Structure and Bonding) Liên kết (bonding) C=O - 01 liên kết σ (do xen phủ orbital lai hoá (hybridized) sp C & O) - 01 liên kết π (do xen phủ bên orbital 2p) CẤU TẠO (Structure and Bonding) Liên kết (bonding) C=O DANH PHÁP (Nomenclature) DANH PHÁP (Nomenclature) ALDEHYDES TÊN IUPAC (IUPAC names) + Chọn dây dây dài có chứa nhóm -CHO + Thay hậu tố –e tên hydrocarbon tương ứng thành –al Nhóm – CHO liên kết trực tiếp với vòng: dùng hậu tố -carbaldehyde Many aldehydes and ketones occur naturally O H trans-2-hexenal (alarm pheromone of myrmicine ant) Many aldehydes and ketones occur naturally O H citral (from lemon grass oil) 6) Cannizzaro reaction (self oxidation/reduction) a reaction of aldehydes without α-hydrogens COO- CH2OH CHO conc NaOH Br Br H2C=O + conc NaOH CH3OH + HCOO- Br Formaldehyde is the most easily oxidized aldehyde When mixed with another aldehyde that doesn’t have any alpha-hydrogens and conc NaOH, all of the formaldehyde is oxidized and all of the other aldehyde is reduced Crossed Cannizzaro: CH=O CH2OH + H2C=O conc NaOH + HCOO- OCH3 OH vanillin OCH3 OH ketone ROR aldehyde RCOOH ROH alkene RX Alcohols are central to organic syntheses RH alkyne How you make Aldehydes? • o Aldehydes from Oxidation of alcohols – Problem is over oxidation to ACID! CH Cr22OO77 CH33CH CH22OH OH ++ KK22Cr ethanol ethanol OO CH CH33CH CH H+ H+ acetaldehyde acetaldehyde OO H+ H+ + K Cr O CH + K22 Cr22 O77 CH33CH CH acetaldehyde acetaldehyde Practice a couple ………… OO CH CH33CC OH OH acetic aceticacid acid How you make Ketones? • o Ketones from Oxidation of alcohols OH OH H+ H+ CH CH CH + K Cr O CH33 CH CH33 + K22 Cr22 O77 2-propanol 2-propanol O O CH CH33CC CH CH33 ++ K K22Cr Cr22O O77 H+ H+ acetone acetone Practice a couple ………… O O CH CH33CC CH CH33 acetone acetone N.R N.R Synthesize benzaldehyde three different ways CH2OH K2Cr2O7 special conditions CH(OOCCH3)2 CH3 CrO3 CH=O H2O (CH3CO)2O benzaldehyde O C Cl LiAlH(O-t-Bu)3 Synthesize benzophenone three different ways OH CH O + C Cl O + C Cl NaOCl AlCl3 CuLi O C cyclohexanone, 4-bromobenzaldehyde, 2-pentanone, valeraldehyde, acetophenone, isobutyraldehyde, using a different method for each one O Br oxidation of 2o alcohol O CH3CH2CH2CCH3 R2CuLi + R'COCl O CH3C Friedel-Crafts acylation CHO oxidation of Ar-CH3 CH3CH2CH2CH2CHO oxidation of 1o alcohol CH3 CH3CHCHO reduction of acid chloride H OH (CH3CH2CH2)CuLi CH3 O C Cl O K2Cr2O7 + + CH3 O CH3CH2CH2CCH3 O C Cl AlCl3 O CH3C Br CH3 (CH3CO)2O CH3CH2CH2CH2CH2-OH CH3 O CH3CHC Cl H2O CrO3 Br K2Cr2O7 special conditions LiAlH(O-t-bu)3 The methods could be reversed for the last two syntheses CHO CH3CH2CH2CH2CHO CH3 CH3CHCHO