!!!!!!!!!!!!!!!!1!CHM!301!!!Fall!2018!!Fall!Break!Proble m!Set!!Part!I!–!Intro!to!13C!NMR.!!!!!1.!!On!the!blank!13C!NMR!spectrum!below,!fill!in!the!approximate!regions!for! each! type!o f!signal!listed!here.! !!The! range! for! methyl!is!sho wn.!!Note!a!13C!NMR!list!of!chemical!shifts!on!the!last!page.!!!!!13C!NMR:!!!!!!!!!!!!!!!!!a. R-CH2Rb. R2C=Oc.RCHORCROOd.e. R-CH2-NR2f. R2CH-Clg.CNRh.CRi.COj. R3C-OR200150 100 50 0δ (ppm)200150 100 50 0R-CH3!!!!!!!!!!!!!!!!2!II.!!Distinguishi ng!Between!Compounds!Usi ng!Spectral!Techniques!!2.!!!Consider! the!pairs!of!m olecules!shown!be low.!!For!each!spectral!technique,!give!the!main!predictable! difference(s)! that! you! could! use! to! distinguish! between! these!compounds.!!(Note!that! in!some!cases! there!may!not! be!a! predictable!difference!for!a!given!technique.)!!!!UV:!! !!MS:!! !!IR:!! !!1H!NMR:! !!!13C!NMR:! !!!!!!!!UV:!! !MS:! !!IR:!!!1H!NMR:! !!!13C!NMR:! !!!!!!!!!! ! ! ! ! ! ! ! ! ! ! Continued…!vs.H3CONHvs.H NOCH3!!!!!!!!!!!!!!!!3!!!!UV:! !!!MS:! !!IR:! !!!1H!NMR:! !!!!!!13C!NMR:! !!!!!!!!UV:! !!!MS:! !!IR:! !!!1H!NMR:! !!!!!!13C!NMR:! !!!!!! ! ! ! ! ! ! ! ! ! ! Continued…!vs.OOvs.O!!!!!!!!!!!!!!!!4!!!!UV:! !!MS:!! !!IR:!! !!1H!NMR:! !!!!!13C!NMR:!!!!!!!!!!!!!UV:!! !!MS:!! !!IR:! !!!1H!NMR:! !!!!!!!13C!NMR:! !!!!!!OH3CCH3CH3OH3CCH3CH3vs.vs.!!!!!!!!!!!!!!!!5!! 3 .!!!%For%each%of%the%pairs%of%molecules%listed%below, % determine%whether%the%given%technique%could%definitively%distinguish%between%the%two.%%%If%the%technique%can%differentiate%the%two%compounds,%explain%how.%%%If%the%technique%cannot%distinguish%them,%explain%why%and%suggest%an%alternative%technique%(IR,%UV,%Mass%spec,%1H%NMR,%13C%NMR)%that%could,%making%sure%to%justify%your%answer%with%one%clear%point.%%You%may%choose%each%alternative%technique%only%once%on%th is%page.%%!!!!!!!!!!!!!!!!!!!!!!!!6!4.!!Predict!the!1H!NMR!spectrum!for!compound!A.!!a)!!First,!identify!and!label!each!set!of!non-equivalent!pro tons!(HA,!HB,!HC).!!!!b)!Predict!the!approximate!chemical!shifts!for!each!set!of!chemically!equivalent!protons.!!!!!!!!!!!!!!!!c)!!Next,!determine!the!multiplicity!of!each!signal!(singlet,!doublet,!triplet,!etc.).!!Explain!which!protons!are!responsible!for!this!splitting!pattern.!!Suggest!J!values!for!each.!!!!!!!!!!!!!!!!!!!!! ! ! ! ! ! ! ! ! ! ! Continued…!!CH3CH3H3CH3COOA!!!!!!!!!!!!!!!!7!d)!!Draw!the!predicted!spectrum!on!the!blank!one!provided!below.!!Clearly!label!each!peak!corresponding! to !each!set!o f!protons! !(HA,!HB,!HC,!etc.),!and!predict!the!integral!for!each!sig nal.!!!!!!!!! !129 6 3 0δ (ppm)All J approx. 7 Hz!!!!!!!!!!!!!!!!8!5.! Match! each! of! the! following! compounds! to! the! proper!13C! NMR! spectrum! (proton!decoupled)!!below.!!!!(Different!carbons!will!give!distinctly!different!peaks;!ignore!slightly!thickened!lines.)!!!! !MeMeMe MeMeMeMeMeMeMeMeMeMe!!!!!!!!!!!!!!!!9!6.! Match! each! of! the! following! compounds! to! the! proper!13C! NMR! spectrum! (proton!decoupled)!below:!!!!!!!! MeMeMeMeMeMeOH O MeOHMeMeOH!!!!!!!!!!!!!!!!10! Spectroscopy Data Tables 13 Z:\files\classes\spectroscopy\typical spectra charts.DOC d0 - 30 ppmSimple alkane carbonsCH3CH2CHd20 - 40 ppm d30 - 50 ppmd50 - 60 ppm sp3 carbon next to oxygenCH3Od55 - 80 ppmd60 - 80 ppmd10 - 50 ppm sp3 carbon next to nitrogenCH3Nd35 - 55 ppmd50 - 70 ppm sp3 carbon next to bromine or chlorine (X = Cl, Br)d25 - 50 ppmd60 - 80 ppm sp carbon (alkynes) sp carbon (nitriles)CNCCδ70 - 90 ppm δ110 - 125 ppm sp2 carbon (alkenes and aromatics) simple sp2 carbon resonance donation moves δ lower,resonance withdrawal moves δ highersp2 carbon attached to an electronegative atom (X = oxygen, nitrogen, halogen) or Cβ carbon conjugated with a carbonyl groupCHCXδ100 - 140 ppmδ140 - 160+ ppmCOX carboxyl carbons (acids, esters, amides)δ160 - 180 ppmCOHδ180 - 210 ppmCORaldehyde carbons, lower values when conjugatedδ180 - 220 ppmC ketone carbons, lower values when conjugatedd30 - 60 ppmCHCX(q)(t) (d)(s)COd70 - 90 ppm(s)(q)(t) (d)CNd50 - 70 ppm(s)CXd60 - 80 ppm(s)(q)(t)(d)(d)(t)(d)(s)(s) Similar chemical shift information presented in a different format. Remember, proton decoupled carbons appear as singlets. When carbons are coupled to their hydrogens, carbons follow the N+1 rule. Methyls = q, methylenes = t, methines = d, and carbons without hydrogen appear as singlets = s. DEPT provides the same information. Carbon chemical shifts are spread out over a larger range than proton chemical shifts (they are more dispersed), so it is less likely that two different carbon shifts will fall on top of one another. The relative positions of various types of proton and carbon shifts have many parallel trends (shielded protons tend to be on shielded carbons, etc.)CH2OCH OCH2NCH NCH2XCH