specID - TOPIC 9. STRUCTURE DETERMINATION (chapter 9 and...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
CHEM 2311 B Topic 9 slide 1 TOPIC 9. STRUCTURE DETERMINATION (chapter 9 and part of chapter 2) CHEM 2311 B Topic 9 slide 2 OBJECTIVES 1. Use combustion analysis to determine empirical formula. 2. Determine molecular weight (and molecular formula) from mass spectrometry. 2. Calculate number of rings and double bonds from molecular formula. 3. Determine functional groups present from infrared spectroscopy. 4. Use 1 H and 13 C NMR spectroscopy to identify other structural features. 5. Combine conclusions from individual techniques to determine the structure of organic compounds. Problems in this section will be restricted to the following classes of aliphatic and aromatic compounds: Alkanes, alkenes, alkynes, alkyl halides, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, acyl chlorides, anhydrides, amides, amines, nitriles
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CHEM 2311 B Topic 9 slide 3 Chapter 9 9.1 Introduction 9.2 Nuclear Magnetic Resonance Spectroscopy (NMR ) 9.3 Interpreting Proton NMR 9.4 Nuclear Spin: 9.6 Shielding-Deshielding of Protons 9.6 Shielding and Deshielding 9.7 The Chemical Shift 9.8 Chemical shift Equivalent and Non-equivalent Protons 9.9 Signal Splitting: Spin-Spin Coupling 9.10 Proton NMR Spectra and Rate Processes 9.11 13 C NMRR Spectroscopy 9.11 A, B, C only 9.13 An Introduction to Mass Spectrometry 9.13 The Mass Spectrometer 9.14 Formation of Ions: Electron Impact Ionization 9.15 Depicting the Molecular Ion 9.16A Fragmentation by Cleavage Skip 9.5 Detecting the Signal FT NMR 9.11 D, E 9.12 Two-dimensional NMR 9.16B-D 9.17 thru 9.20 (end) CHEM 2311 B Topic 9 slide 4 ? COMBUSTION ANALYSIS C x H y O z + O 2 xCO 2 + ( y / 2 )H 2 O Measure mass of CO 2 and H 2 O formed from a known mass of compound; data cited as mass% of each element present. Generally do not measure mass%O. e.g. , C H O Mass% 54.51 9.09 Mole Ratio = = Empirical formula Be careful when rounding, elemental analyses provided ±0.4 mass% - do not round by more than 0.05 to 0.1. Multiply ratios before rounding.
Background image of page 2
CHEM 2311 B Topic 9 slide 5 EMPIRICAL AND MOLECULAR FORMULAS; DETERMINATION OF “SODAR” Molecular formula is an integral number of times the empirical formula. C 2 H 4 O Sum of double bonds and rings (“SODAR”) For C,H,O: (2#C + 2 – #H) / 2 For C,H,O,N,Hal: (2#C + 2– #H – #Hal + #N) / 2 Each Hal replaces a H Each N adds an extra H S,O: no effect on calculation If SODAR calculated from empirical formula is not a positive integral (or 0), this cannot be the molecular formula. C 2 H 4 O MOLECULAR FORMULA COULD BE: ? CHEM 2311 B Topic 9 slide 6 MASS SPECTROMETRY Theory and Experiment M + e (70 eV) M + + 2e M + lower mass ions S:9.12-9.18
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CHEM 2311 B Topic 9 slide 7 Data Available e.g. , mass spectrum of ethane, CH 3 CH 3 Ions also fragment, which can give further clues about the structure (beyond scope of this course). Knowledge of molecular weight (from mass spec) and empirical formula (from combustion analysis) allows determination of molecular formula.
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 58

specID - TOPIC 9. STRUCTURE DETERMINATION (chapter 9 and...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online