Disclaimer: The definitions & photos used herein belong to: Organic Chemistry by David Klein 2 nd edition, Wiley publishers

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1 Fall 2017 Organic Chemistry I Review by Elizabeth Ruelke fr SARC 12/2/17 8:00-8:02am Intr/disclaimer 8:02-8:04am Ch1 structure and bnding Mass number weight f the atm Atmic weight S rbital lcated within sigma bnds P rbital lcated within pi bnds Valence electrns lcated n the uter shell Bnding electrns shared between atms Nnbnding electrns lcated lcally n ne atm Lewis structures structure shwing the electrn lcatin n atms Frmal charge charge n the verall mlecule cumulated frm the individual charges n each atm. Ismers same mlecular frmula, different arrangement f atms. Octet rule there must be 8 electrn in the uter shell Resnance electrns mvement thrughut mlecule Delcalized lne pairs participate in resnance Lcalized lne pairs dn t participate in resnance VESPR thery electrn repulsin yields different mlecule gemetry hybridizatins. Sp3 n lne pairs is tetrahedral; ne lne pair is pyramidal; tw lne pairs is bent Sp2trignal planar Splinear Cndensed frmula written ut mlecular frmuala withut written bnds CH 3 CH 2 CH 3 Electrnegativity increases up and t the right f the peridic table 8:04-8:06am Ch2 acids and bases Lewis acid electrn acceptr Brnsted acid prtn dnr (aka LA) Lewis base electrn dnr Brnsted base prtn acceptr (aka LB) Keq= [prducts]/[reactants] pka= -lg Ka Increasing acidity ges dwn and t the right n peridic table Cmparing acidity f certain mlecules: MARIO Mlecule make sure yu re cmparing similar mlecules Atm make sure yu evaluate the electrnegativity f the atms Resnance the mre resnance available the better the acid Inductin the mre inductive effects the mre acidic Orbital the mre s character in rbital the mre acidic Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

2 8:07am-8:09am Ch3 rganic mlecules and functinal grups Intermlecular frces van der waals diple-diple hydrgen bnding inic Biling pint increases with mre hydrgen bnding Larger the surface area higher the BP Melting pint mre glbular/symmetrical higher MP SlubilityLike disslves like 8:09am-8:16am Ch4 alkanes Straight chain vs branched chain Cyclalkanes Nmenclature w/substituents Always priritize lwest number t substituents, giving preference t alchls Newman prjectins (staggered, eclipsed) (anti/gauche) Angle strain any angle belw/abve C Cyclprpane Trsinal strain energy frm verlapping grups (eclipsed) Cyclbutane Steric strain energy frm verlapping electrn cluds t-butyl grup base Chair/Bat cnfrmatin (ax/eq) & ring flipping Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

3 Cnstitutinal ismers same mlecular frmula, different cnnectins Stereismers (cis/trans) same mlecular frmula, same cnnectins, different special arrangement OIL RIG (xidatin/reductin) Oxidatin is lss f electrns, r increased xygen cnnectins Reductin is gain f electrns, r decreased xygen cnnectins Prblems: Nmenclature: m-chlrphenl Newman prjectin: C2-C3 3-chlr-2-butanl Lwest energy cnfrmer Highest energy cnfrmer Chair/Bat: cis 1,3-diethylcyclhexane vs. trans 1,3-diethylcyclhexane Lwest energy? Highest energy? Stereismers r cnstitutinal ismers r same? (CH 3 ) 3 CCH 2 CH(CH 3 ) 2 and (CH 3 ) 2 CHCH 2 C(CH 3 ) 3 8:16-8:22am Ch5 sterechemistry Achiral vs Chiral R clckwise (dextrrtary: plarized light t the right) S cunterclckwise (levrtary: plarized light t the left) Mes ptically inactive Stereismers: Enantimers mirrr images, nn-superimpsable Diasteremers nt superimpsable and nt mirrr images Tw enantimers have identical physical prperties except plarimetry Optically active has chirality, nt mes, part f chemical prperty f a substance Racemic definitin 50/50 mixture f enantimers Specific rtatin [a]= specific rtatin a=bserved rtatin c=cncentratin (g/ml) l= path length (dm) Enantimeric excess Prblems: Draw bth R/S f 2-chlr-2butanl Draw bth R/S f 3-brm-3-chlrhexane Specific rtatin: Yu add 0.3g f sucrse t 10mL water. Run the sample acrss 10cm length. The bserved rtatin is What is the specific rtatin? Enantimeric excess: Scientist was t create synthetic adrenaline, but experiment is cntaminated. Pure adrenaline is The bserved rtatin is -45. What is the ee%? ***Nte: final number is the excess dn t frget t add the difference f racemic*** 8:22-8:32am Ch6 understanding Organic reactins Substitutin rxn replacing X with Y n a mlecule Additin rxn adding mlecules acrss duble r triple bnds Eliminatin rxn remving HX frm mlecule t create duble bnd Bnd making /bnd frming Cncerted mech single step Stepwise mech tw step, with intermediate state Bnd cleavage: Heterlytic ne f the pair f atms receives bth electrns Carbcatins: C+ Carbanins: C: -- Hmlytic electrns are evenly split between atms Radicals: C Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

4 Electrphile atm lacking electrn density, vulnerable t attack Nuclephile atm/bnd with lne pair electrns, will attack substrate H= bnds brken bnds frmed Endthermic + H absrbs heat frm system Exthermic - H releases heat int system Thermdynamics G= H T S Exergnic releases energy int system Endergnic absrbs energy frm system K eq >1 crrelates with G (-) favrs prducts K eq <1 crrelates G (+) favrs reactants Energy diagrams Peaks=transitin state Valley=intermediate Energy f activatin (E a ) difference in energy between reactants and transitin state Catalysts speeds up reactin rate, usually acids r metals; lwer activatin energy Kinetics= study f reactin rate Rate= k [reactants] Sn1 rate= k[reactant] Sn2 rate= k[reactant][nuclephile] Prblems Substitutin, Eliminatin, r Additin? Chlrbutane + HBr Brmbutane + HCl 2,4-dibrmbutane + 2NaH 2-butyne + 2HBr Butane + Br2 1,2-dibrmbutane Acetylene + 2HBr 1,2-dibrmethane 2-brmprpane + NaOH 2-prpanl + HBr 2,2-dichlrpentane + NaNH 2 2-chlr-2-pentene + NH 3 Identify electrphilic and/r nuclephilic sites n the fllwing: Phenl Pentanl 3-brm-2-hexanl Carbxylic acid Draw the fllwing energy diagrams: Exergnic 2 step rxn Endergnic 2 step rxn Exergnic 1 step rxn Endergnic 1 step rxn 8:32am-8:41am Ch7 alkyl halides and nuclephilic substitutin Vinyl halide & Aryl halides unfavred and unreactive in substitutins Allylic halide & Benzylic halide favred and reactive in substitutins Nmenclature Cmmn names: t-butyl-, isbutyl-, sec-butyl-, isprpyl- Bnd plarity based ff relative electrnegativity s f the atms n bnd Gd leaving grups easily leave the mlecule, usually halides Nuclephilicity increases t the right and dwn peridic table Steric hindrance can determine site f attack See NaOH versus t-butxide Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

5 Substitutin Reactins Sn1 Sn2 Rate =k[reactant] =k[reactant][nuclephile] Mechanism Stepwise (carbcatin intermediate) Cncerted Substrate Res > 3 > 2 > 1 1 > 2 > 3 Nuclephile Weak Strng Slvent Prtic: water, acetic acid, ammnia Aprtic: DMSO, DMF, acetnitrile Prduct Type Racemic mixture Inverted chirality due t back-side attack Hammnd pstulate (Sn1) shws 3 has lwer activatin energy ver 2 fr carbcatin frmatin Prblems Shw prduct, arrw pushing and indicate Sn1 r Sn2: 2-brm-3-methylpentane + H 2 O 2-brm-3-methylpentane + NaOH 2-pentanl + TsOH/py 2-methyl-3-OTs-pentane + EtOH 2-chlrbutane + NaCN 3-brm-3-methylpentane + H 2 O 1-chlr-3-methylpentane + NaOH 2-methylcyclhexanl + H 2 O 2-idcyclpentane + MeSH 8:41-8:50am Ch8 alkyl halides and eliminatin reactins Eliminatin Reactins E1 E2 Rate =k[reactant] =k[reactant][nuclephile] Mechanism Stepwise (carbcatin intermediate) Cncerted Substrate 3 > 2 > 1 3 > 2 > 1 (antiperiplanar) Base n/a Strng Hammnd pstulate (E2) shws trans substitutin is preferred ver cis Trans Alkene mre stable than cis alkene due t steric strain E/Z nmenclature: E largest grups n ppsite sides f duble bnd Z largest grups n same side f duble bnd Zaitsev rule: indicates the mst stable alkene is the mre substituted duble bnd Zaitsev mre substituted prduct Hffman lesser substituted prduct *** Triethylamine & t-buok give preferential Hffman prduct Nuclephile vs Base Prblems List E1, E2, Sn1, r Sn2 fr belw and majr/minr prducts Chlrpentane + NaBr 3-brm-3methyl-pentane + NaSH 2-brmpentane + NaH Brmpentane + NaOH 2-brmpentane + NaOH 2-brm-3-methylpentane + H2O 8:50-9:00am BREAK TIME Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

6 9:00-9:06am Ch9 Alchls, Ethers, and related cmpunds Nmenclature Naming alchls Naming epxides Naming Ethers Synthesis Williamsn ether synthesis Epxide have angle strain Breaking in acid additin at mre substituted side Breaking in base additin at less substituted side Alchl Additin f primary alchl (1. BH3, THF 2. H2O2, OH) Additin f secndary alchl (H2SO4) Eliminatin f alchl via E1 f 2 /3 degree alchl Eliminatin f alchl via E2 f 1 degree alchl LeChatelier s principle Reagents NaH strng base, preparatin f ethers TsCl, py replace OH t be gd leaving grup H2SO4dehydratin if cncentrated, hydratin if dilute HCl acid breaking f epxide KOH base breaking f epxide NaNH2 base NaOCH3 frmatin f ether with base POCl3 in py replace alchl with chlride (backside attack) SOCl2 replace alchl with chlride (backside attack) PBr3 replace alchl with brmine (backside attack) NaCN base, and elngatin f carbn chain Br2/I2 adds trans vicinal halides KSH replace alchl r break epxide ring; adds thil grup (backside attack) Disulfide Zn/Hcl thil grups Prblems: Give prduct(s) Acetylene 1. NaH, 2. MeBr 3. H2, Lindlars 4. Dilute H2SO4 2-butanl 1. H2SO4, heat, 2. HBr 3. t-buok 1,2-epxycyclhexane 1. NaBr 2. NaH 3. Br2 1-pentene 1.BH3, THF 2. H2O2, OH 3. TsOH, py 4. NaSH 1,2-epxy-2-methylcyclhexane 1. NaOH 2. POCl2, py 9:06-9:12am Ch10 alkenes Calculating the degrees f unsaturatin ½(2C +2 + N H X) Each degree represents 2 less H, r an additinal duble bnd Nmenclature (vs alchl, functinal grups, etc) -diene, -triene, E/Z (cis/trans) Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

7 Making alkenes -OCH3 vs OC(CH 3 ) 3 different prducts acid (H2SO4 n alchl) vs base (-OCH3) Reagents Hydrhalgenatin (HX) Hydratin (H2O, H2SO4) Halgenatin (X2) Halhydrin frmatin (X2, H2O) Hydrbratin-xidatin (1. BH3, THF, 2. H2O2, -OH) Markvnikv additin hydrgen ges with mre hydrgens Prblems: Shw arrw pushing 2-butanl + H2SO4, heat 2-butanl + -OCH3 Pentene + HBr 2-butene + H2O, H2SO4 2-butene + Br2 2-pentene + Br2/H2O Pentene 1. BH3, THF 2. H2O2, OH 9:12-9:18am Ch11 alkynes Nmenclature (-diynes, -triynes) If alkene and alkyne, g with the lwer numbering Preparatin f alkynes frm alkenes NaNH2, NaH, etc Reactins t alkynes H2, lindlar s (cis additin) H2, pt (reduce t alkane) NaNH3 (trans additin t alkyne) X2 Water additin Acid tautmerizatin (enl t ket) H2O, H2SO4, HgSO4 (mre substituted alchl) BH3, THF 2. H2O2, -OH (lesser substituted alchl) Elngating carbn chains Add epxides (then H2O) t give terminal OH Retrynthesis (final beginning prduct): g back ne step/precursr at a time Synthesis (acetylene) given final Prblems Acetylene 1. NaH 2. EtBr 3. NaH 4. MeBr 5. H2, lindlar s Acetylene 1. NaH 2. PrpylBr 3. Br2 (excess) Acetylene 1. NaH 2. Oxirane 3. H2O Acetylene 1. NaH 2. EtBr 3. BH3, THF 4. H2O2, OH Acetylene 1.NaH 2. MeBr 3.NaH 4. MeBr 5. H2SO4, HgSO4, H2O 9:18-9:25am Ch12 Oxidatin reductin Reducing agents Na NH3 (trans) NaBH4 LiAlH4 (LAH) Oxidatin agents KMnO4/OsO4 syn additin) MCPBA (expy) RCO3H 2. H2O (anti dil additin) O3 2. Zn, H2O (cleavage f alkene) Carbxylic acids n alkynes) K2Cr2O7 (r CrO3 with H2SO4, H2O) (yield ketne) PCC (ketne) Prblems Butanal 1. LAH excess 2. H2O 3.TsOH, py 4. NaBr 5. NaH 2-pentanl 1. CrO3, H2O, H2SO4 2. NaBr 3. H2O Acetylene 1.NaH 2. MeBr 3. Br2 4. KMnO4, cld Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

8 Prpanl 1. H2SO4, heat 2. Br2 3. NaH (2eq) 4. NaNH3 5. MCPBA Cyclpentene 1. O3 2. Zn, H2O 3. LAH (excess) 4. H2O 2-methylcyclpentanl 1. TsOH, py 2. NaBr 3. NaH 4. RCO3H 5. H2O 9:25-9:32am Ch13 Mass Spec & IR spectrscpy Mass Spec Yields mlecular frmula, presence f Br/Cl, via fragmentatin and detectin f carbcatins Base peak (100%), mass-t-charge (m/z), (M) + mst cmmn fragment, (M+1) + secnd mst abundant fragment (M+2)+ chlrine (1:3 rati peaks), brmine (1:1 rati peaks) Fragmentatin/Lss: M-15 (methyl), M-29 (ethyl), M-43 (prpyl), M-57 (butyl), M-18 (H2O) Prblems Mlecular frmula? Brmine, Chlrine, r neither? IR spec Yields functinal grups present n mlecule, via bending and stretching Diagnstic regin: (cm -1 ) mst imprtant frequencies Fingerprint regin: (cm -1 ) dn t pay attentin t this Shifting is affect by % s character, bnd length, difference in weight between atms Signals can be brad, strng, r weak Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

9 Prblems Carbxylic acid, alchl, neither? Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

10 Carbxylic acid, alchl, amine, neither? Match Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

11 9:32-9:40am Ch14 NMR H NMR Cmparing signals: hmtrpic, enantitrpic, diasteretrpic Characteristics: Lcatin (aka shift δ) determined by inductive neighbrs Dwnfield (high number) vs upfield (lw number) Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

12 Area (integratin I) hw many prtns are represented in the signal Height represents integratin relative t each ther (rati) 2:3:2:3 Shape (splitting m) hw many neighbrs (n+1) Singlet= n neighbrs; dublet= 1 neighbr; triplet= 2 neighbrs, etc. Prblems Determine number f signals Determine number f signals and shift C NMR Identify number f signals f C 13 Range: Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

13 Types f C NMR: Prblems Determine number f signals, shift, integratin Determine structure 9:40-9:45am Ch15 Radical Reactins Radical stability: res > 3 > 2 > 1 > Me Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers

14 Definitins Stages: Initiatr (heat, light, NBS, Acyl perxides) Prpgatin Terminatin Types chlrinatin (mre energy favrable, incmplete prduct frmatin) vs brminatin (cmplete prduct frmatin, higher energy state) Prduct racemic Reagent HBr, ROOR (gives anti-markvnikv prduct) Prblems Acetylene 1.NaH 2.MeBr 3.NaH 4.MeBr 5.HBr, ROOR 2-butene 1.Br2 2. NaH (2eq) 3. NaNH3 4. NBS, hv 9:45-10:00am Final survey, Questins, and Clsing Statements Please leave rm clean Disclaimer: The definitins & phts used herein belng t: Organic Chemistry by David Klein 2 nd editin, Wiley publishers