Reactions and Mechanisms of Ethers and Epoxides - Prof. Richard Hubbard, Study notes of Chemistry

Download Reactions and Mechanisms of Ethers and Epoxides - Prof. Richard Hubbard and more Study notes Chemistry in PDF only on Docsity! Reactions of Ether: 1. Acidic Cleavage * Ethers are generally inert and therefore useful as reaction solvents * Strong acids will cleave them however: General Reaction: ON HCH a CH3 HBr. H20 cr Reftinc CY + CH3CH2Br Ethyl phenyl ether Phenol Bromoethane Reaction Specifics Ethers Containing Primary and/or Secondary Alkyl Groups: More hindered —_Less hindered fh = HI CHgCH—O—CHaCHg — | Sn2 creo cach Sn2, CHy CHycH—OH + I —CHaCHy CH3 7 CH Ethyl isopropyl! ether * Isopropyl! alcoho! Iodoethane 1 2007 Thomson Het Esveaton Ethers Containing Tertiary Alkyl, Benzylic or Allylic Groups: fercs vie Sl Mechenism CHg CH, Product cHse—o-—cH,cH,ch; 48 crgc—er + HOCH,CH,CH at 2CH2CHs at @CH2CHy mt ghares CHy CH3 fo SGibLe tert-Butyl propyl ether 2-Bromo-2- 1-Propanol methyipropane Fash rans et occur Why? formatton ob Shble corks cating ~T Medemte temps ar As & Reactions of Ether: 2. Claisen Rearrangement * Specific to allyl aryl ethers General Structure: ots Initial Ether Formation: on wat Pen es 6A] om Claisen Rearrangement: Pericyclic Reaction (concerted) allyl phoryl tow Ol = at Mechanism (alkene + peroxy acid): el to: WVrkte — Ce ° ho Synthesis Involving Halohydrins: Mechanism: ys On H ! Clz NaOH | OG - H20 “HO " Ga cl Cyclohexene trans-2-Chloro- 1,2-Epoxy- cyclohexanol cyclohexane {8 2007 Thomson Hicher Education Practice: CPR Sf ™ —~ ew ae yeh ste c* oo mehr ON ~~ ———— Cc— bem ,2s". med K +r an ef Mn No/ The erisine! alleene”s Stes chemistry is Con Served in He exfexide fing Epoxide Reactions: Acid Catalyzed Ring Opening * Epoxides can be cleaved in acidic conditions just like ethers (hydrolysis) * They react under much milder conditions due to ring strain Example: Or Hy0 \ Sa < ,cm—c, os eho” wd ou en, K my te, 1,2-drol (vteine dial) Mechanism: ., nO, H H é éf P= hee = ck» ‘ WI +OH2 su 4 eS wand 1,2-Epoxycyclo- trans-1,2-Cyclohexanediol hexane (86%) Recall the following: H Oc= H Cyclohexene trans-1,2-Dibromo- cyclohexane {©2007 Thomson Hisher Education