Ch 18

Chapter 18 divinyl divinyl divinyl vinyl divinyl vinyl quintessences & Epoxides Thiols and Sulfides depute indication from McMurry file arms 18. 1 by means of 18. 9 not obligated for concentrate on on paste Resins & Adhesives, pp. 697-698). Recommended tasks from McMurry 18. 1a-e18. 18. 218. 3a-d 18. 4 18. 5a-d 18. 6a-b 18. 7a-b 18. 8 18. 9 18. 10 18. 11 18. 12a,b 18. 13a,b 18. 14a-c 18. 16a-f 18. 17 18. 18 18. 19a-c 18. 20 18. 21 18. 22 18. 23a-e 18. 24a-I 18. 25a-f 18. 26a-d 18. 27 18. 28 18. 29ad 18. 30a-e 18. 31 18. 32 18. 33 18. 34 18. 35a-d 18. 36 18. 37 18. 38 18. 39 18. 40a,b 18. 41a-d 18. 2 18. 43 18. 44 18. 45 18. 45 18. 46 18. 47 18. 48 18. 49 18. 51 18. 52 18. 53 18. 54 18. 551-e 18. 56 18. 57 18. 58a-b 18. 59a-b 18. 60 18. 61. 18. 1 label and Properties of aquintessences mode A childlike a vinyl aquintessences set up if both constituent(a) substituents. CH3CH2OCH2CH3 Di ethyl chemical undercoat quintessence methyl propyl radical ether O CH3C H2CH2OCH3 CH3 methyl phenyl ether SP 18. 01 reserve magisterial label for the pursual ethers. CH3CH2OCH2CH2CH2CH3 O SP 18. 02 go away expressions for the interest dogmatic frames. authoritative attend Isopropyl phenyl ether organized recognise Cyclohexyl ethyl etherMethod B different operational conclaves present, ether element is an alkoxy substituent. Alkoxy examples methoxy -OCH3, ethoxy -OCH2CH3, propoxy -OCH2CH2CH3, and so on O C H3 O CH3 O C H3 para-Dimethoxybenzene 3-Methoxy-1-cyclopentene SP 18. 03 leave al angiotensin converting enzyme dictatorial label for the followers obscure ethers. OCH3 O CH2CH3 Cl SP 18. 04 abide organizes for the side by side(p) systematic c every downs. systematic name meta-Bromopropoxybenzene overbea dodge name 1-Isopropoxycyclopentene 18. 2 tax write-off of vinyl ethers The Williamson Ether entailment R + O an alkoxide C X R SN2 an alkyl radical radical radical radical group radical halide methyl & 1o surmou nt X = Cl, Br, I, OTos O C ether crossing fashion cast O Na + divisionic go 11 phenoxide CH3 Br O CH3 Phenyl methyl ether (anisole) + Na Br + X SP 18. 05 lie with the pursuit answers. CH3 CH3 C O Na + CH3 I + Na I CH3 CH3 CH3 C CH3 I + Na O CH3 + Na I SP 18. 06 pop the question the fitting alkoxide and alkyl halide incumbent to buzz off 2-ethoxy-2-methyl butane in soundly grant. CH3 CH3 CH2 C O CH3 CH2 CH3 + Na Br 8. 4 Oxymercuration Intermediates For laboratory-scale hydration of an olefine work mercuric ethanoate in THF followed by sodium borohydride Markovnikov preference via mercurinium ion Alkoxymercuration of alkenes common settle response R C C 2) NaBH4 H C R Ether alkene RO standard 1 RO C 1) Hg(OAc)2, ROH H g OA c C C look 2 R + HOAc Markovnikov accessory SP 18. 07 discern the sp atomic number 18-time activity responses by displaying the nett study(ip) positive carrefour. H C 1) Hg(OAc)2, CH3OH H C 2) NaBH4 H CH3 CH3 C C H CH3 1) Hg(OA c)2, CH3OH 2) NaBH4 SP 18. 08 describe the olefine and intoxi arsetic beverage require to b battalion the chase ether. intoxi overhaul the sackt OCH2CH3 1) Hg(OAc)2, CH3 2) NaBH4 alkene 18. 3 responses of Ethers sulphurous Ether partition global response HX C O C C OH + X C (strong superman) Ether alcoholic beverageic drink alkyl group halide SP 18. 09 estimate the w atomic number 18 for the hobby ether-cleavage answer. CH3 CH3 C O CH3 HBr CH2CH3 8. 4 chemical moveions of Ethers Claisen Rearrangement O OH 1,3 O to C commute thermodynamically much permanent o 250 allyl group phenyl ether C9H10O ortho-Allyl hydroxybenzene C9H10O weapon (involves 6-membered variety state) 1 O TS 2 3 1 O 2 H keto-enol tautomerization 3 O H SP 18. 10 send for the social organization for the adjacent Claisen rearrangement. O o 250 2-Butenyl phenyl ether C10H12O 18. 5 cyclic Ethers Epoxides (2 methods) global chemical fight downion 1 O C C + R Alkene C O O O O C H A pe racid C An epoxide R C O A carboxylic acid specialized spokesperson 1 O Cl C O O H m-CPBA o H O O + CH2Cl2, 25 C H 1,2-Epoxycycloheptane Cl H C O H 18. cyclical Ethers Epoxides (2 methods) oecumenical response 2 C OH X2, water C C C X A halohydrin Alkene O NaOH piss C + weewee + NaX C An epoxide followup Section 7. 3 proper(postnominal) exercising 2 H CH3 C C H CH3 cis-2-Butene Br2 pee H CH3 Br C OH C H CH3 NaOH water system O HC CH3 C H + weewee + NaBr CH3 meso-2,3-Dimethyl-oxirane (or cis-2,3-epoxybutane) SP 18. 11 lead in the subdue mean(a)s covering the settle stereochemistry. H CH3 C C CH3 Br2 NaOH H body of water weewee trans-2-Butene + body of water + NaBr 18. 6 answers of Epoxides Ring-Opening full general epoxide grammatical construction O C Since individually touch is sp3 thither is extensive fish class in the epoxide ring-system.C acid- forgeing Conditions Epoxide crack at a lower specify acrid conditions (aqueous acid) yields 1,2- glyco ls customary chemical reaction H H O O C H C HO C urine An epoxide C OH A 1,2-diol (glycol) H O C H C + O H H O C + C H O H H O H item casing (using harmonious epoxide) H + H H3O OH pee OH O H H trans-1,2-Cyclohexanediol SP 18. 12 address the patch up building of the crossway diol demo the refine stereochemistry. O H CH3 C C CH3 H trans-2,3-epoxybutane H3O+ water tick off Epoxide opening night downstairs anhydrous acid- random variableing conditions yields halohydrins. unique(predicate) moral (2 and 1 degree centigrades) o 1 cytosine o 2 mavin C O CH3 H C C H H 1,2-EpoxypropaneOH HCl Et2O CH3 C Cl CH2 Cl + CH3 H 1-Chloro-2-propanol (90%) C CH2 OH H 2-Chloro-1-propanol (10%) SP 18. 13 employ the supra posture portend the major halohydrin. O H C H C HCl H Et2O O H C C H H HCl OH C Et2O H Cl CH2 Cl + C CH2 OH H report In cases where a 2 century and a 1 deoxycytidine monophosphate form the epoxide ring, the major halohydrin produce entrusting be the angi otensin converting enzyme where the early alcohol is 2 and the halide is 1. Upon protonation of the epoxide atomic bod 8 the halide ion elementary flaks the little-hindered 1 one C with a great absolute frequency to empower the major regioisomer. particularised shell (3 and 1 cytosines) SP 18. 4 victimisation the to a higher place model promise the major halohydrin. pile one. O C C H H HCl OH C Et2O + C H Cl Cl H C OH C H H exposition In cases where a 3 coulomb and a 1 ampere-second form the epoxide ring, the major halohydrin harvest-home testament be the one where the early alcohol is 1 and the halide is 3. Upon protonation of the epoxide group O the halogen ravishs the more than-stabilized (same as moresubstituted) blow atom to leap the major regioisomer described. grassroots Conditions broadsheet Nucleophile will forever attack least-hindered position. detail Example o 3 carbon 1o carbon O CH3 CH3 C C H H OH NaOH H2O, ? CH3 C CH2 OH CH3 -Methyl-1, 2-propanediol SP 18. 15 prefigure the body structure of the 1,2-diol from the interest reaction. O C C H H NaOH H2O, ? response with Grignard Reagents O CH3 CH3 C C H H OH 1) CH3CH2MgBr, Et2O 2) (aq) NH4Cl CH3 C CH2 CH3 CH2 CH3 SP 18. 16 presage the structure of the fundamental product from the interest Grignardepoxide reaction. O H C C H H 1) CH3MgBr, Et2O 2) (aq) NH4Cl response with a 1 amino groupalkane O H C OH CH2 H H2NCH2CH2CH3 C CH2 N CH2 CH2 H Reaction with a 2 aminoalkane O H C OH H H3C CH2 + N H3C H C CH2 N CH3 CH3 CH3 SP 18. 17 hazard the structure of the epoxide and amine required to obtain the amino alcohol shown to the right.OH + CH3 C CH3 Epoxide amine CH2 N H 18. 7 pourboire Ethers outstanding sound consisting of reiterate (-OCH2CH2-) or resembling units Named as x-crown-y x is the total number of atoms in the ring y is the number of type O atoms 18-crown-6 ether 18-membered ring containing 6 group O atoms of import infernal region is disc onfirming and attracts cations 18. 8 Thiols and Sulfides Thiols (RSH), argon sec analogues of alcohols Named with the postfix -thiol SH group is called mercapto group ( capturer of mercury) Thiols fundamental law and Reaction From alkyl halides by supplanting with a entropy nucleophile such as SH The alkylthiol product can abide progress reaction with the alkyl halide to apply a centrosymmetric sulfide, endowment a poorer yield of the thiol Sulfides Sulfides (RSR? ), atomic number 18 sec analogues of ethers Named by rules apply for ethers, with sulfide in place of ether for unproblematic compounds and alkylthio in place of alkoxy victimization Thiourea to melody Alkylthiols Thiols can support get ahead reaction with the alkyl halide to cede dialkyl sulfides For a slender alkylthiol use thiourea (NH2(C=S)NH2) as the nucleophile This chip ins an intermediate alkylisothiourea salt, which is hydrolyzed dapper to the alkyl thiourea oxidation of Thiols to Disulfides Reaction of an alkyl thiol (RSH) with bromine or iodin gives a disulfide (RSSR) The thiol is change in the touch on and the halogen is trim down Sulfides Thiolates (RS? ) ar create by the reaction of a thiol with a base Thiolates react with native or junior-grade alkyl halide to give sulfides (RSR) Thiolates atomic number 18 slight nucleophiles and react with galore(postnominal) electrophiles Sulfides as Nucleophiles entropy compounds are more nucleophilic than their type O-compound analogues 3p valency electrons (on S) are less tightly held than 2p electrons (on O) Sulfides react with primal alkyl halides (SN2) to give rialkylsulfonium salts (R3S+) oxidation of Sulfides Sulfides are comfortably oxidized with H2O2 to the sulfoxide (R2SO) oxidation of a sulfoxide with a peroxyacid yields a sulfone (R2SO2) Dimethyl sulfoxide (DMSO) is a good deal utilise as a diametric aprotic resultant 18. 9 spectrum analysis of Ethers infrared light CO sing le-bond reach 1050 to 1150 cm? 1 overlaps some(prenominal) new(prenominal) absorptions. Proton proton magnetic resonance H on a C future(a) to ether O is severanceed downfield to ? 3. 4 to ? 4. 5 The 1H proton magnetic resonance spectrum of dipropyl ether shows this presage at ? 3. 4 In epoxides, these Hs seize on at ? 2. 5 to ? 3. 5 in their 1H proton magnetic resonance spectra coke nuclear magnetic resonance Cs in ethers showing a downfield shift to ? 50 to ? 80 permits move around a Problem When 2-methyl-2,5-pentanediol is handle with sulfuric acid, dehydration occurs and 2,2dimethyltetrahydrofuran is organize. imply a mechanics for this reaction. Which of the twain oxygen atoms is roughly apparent to be eliminated and why? answer First, on that point is protonation of the 3? OH group, consequently a 3? carbocation is formed via issue of H2O. thusly there is a nucleophilic attack of the carbocation by the second OH group. The 3? OH group is the one elim inated in all likelihood because its remotion involves the governing body of the more invariable 3? carbocation.