C 202 1stt Edition CHE Lecture 3 Outline of Last Lectture I S Spectroscop py of Hydrocarbons a Bond d Stretchingg II C Carbon Satu uration a Indeex of Hydroggen Deficien ncy III C Conjugation n a Hybridization bonyl Compounds Carb Outline of Current Lecture R Resonance Review I II I Introduction n to Mass Spectrometrry a Overview b Fraggment Patteerns c Alco ohol MS III E Example Co ompound Currentt Lecture Review of Resonance Resonan nce occurs w when electrrons are shaared among the parts o of a molecule these aree often represented with o one depictio on of the mo olecule and resonance is assumed R Resonance affects a the appearance a e of an IR spectra pectroscopyy Mass Sp Overview Method M of Compound C Analysis thaat utilizes high energy eelectrons to o compare m masses of d different paarts of the saample Destructive D because th he molecules are broken apart by tthe electron ns Masses M and d the relativee abundancce are reporrted Forms F Radiccals and Cattions Mass M Peak M Masss to Charge Ratio m zz o used d to determine scale off entire grap ph Mass Peeak becomess 100 These notes represent a d detailed interp pretation of th he professor s lecture Grad deBuddy is besst used as a supplement to your own notes n not as a substitute Fragmentation Most M comm mon fragmen ntation of alkenes is cleeavage of alllylic bonds to give an allylic a c cation Benzylic B cattions are abundant beccause of reso onance stab bility Alcoholss Alcohols A oftten lose watter when fraagmented Examplee Compound C9H10O 1 IHD I 5 degrees of satu uration therefore assumed a benzzene ring 2 IR I Data nd 1 conffirms aromaatic C C bon 2 Deteermine oxyggen bond C C O at 1688 8cm 1 3 MS M Peaks o Diffe erences between the laast and nextt to last peaaks show losst fragmentss o Know wn loss of 2 29 indicates a methyl grroup