Expt 10'1

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• Expt 10.1
• Qualitative Analysis of
• Alkenes, Alkynes, and Alkyl Halides
• Lab Practical

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Purpose

• Identify an unknown alkyl halide, alkene or
  alkyne
• Physical properties
• Boiling point, nD, density
• Chemical properties
• Solubility in H2SO4
• Spectral properties
• IR, NMR

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Physical Properties

• Boiling point (Exercise D.2, pages 30 - 32)
• Correct for barometric pressure and thermometer
• Refractive index (Exercise E.1, pages 33 - 34)
• Correct for ambient temperature
• Density (Exercise B.2, page 21)
• Convert density data to g/mL

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Chemical Properties

• Solubility Test in H2SO4
• Positive for alkenes alkynes
• dissolves
• color changes
• heat evolved
• Negative for alkyl halides
• two layers

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Chemical Properties
Solubility test

• Alkynes react similarly.
• Alkyl halides do not react.

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Spectral Properties

• IR spectra
• Important alkyl halide absorptions
• 3000-2850 cm-1 sp3 CH bond stretching
• 800-600 cm-1 CCl bond stretching
• Important alkene absorptions
• 3100-3000 cm-1 sp2 CH bond stretching
• 1630 cm-1 CC double bond stretching
• Important alkyne absorptions
• 3300 cm-1 sp CH stretching
• 2150-2100 cm-1 CC triple bond stretching

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No CC, Too symmetrical
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(weak)
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13C NMR

• Chemical shifts indicative of atoms or groups
  attached to the carbon.
• See inside back cover of lab text for ppm
• Alkyl, 0-50 ppm
• C-Cl, C- Br, 20-60 ppm (correct your text!)
• Alkynyl, 70-90 ppm
• Alkenyl, 100-150 ppm

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2-chlorobutane
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trans-2-pentene
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1-pentyne
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2-pentyne
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Pre-lab Preparation

• Read
• Expt. 10.1
• Boiling point (Exercise D.2, pages 30 - 32)
• Refractive index (Exercise E.1, pages 33 - 34)
• Density (Exercise B.2, page 21)
• Review
• IR
• NMR

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Pre-lab Preparation

• Prepare Notebook
• Header Information
• Purpose
• Reference
• Table of reagents, hazards
• sulfuric acid only
• Procedures (two columns)
• Write procedures in sufficient detail for you do
  perform all the necessary tests.

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Procedural Changes

• Unknowns will not be distilled.
• Solubility test is the only chemical test that
  will be performed in lab.
• IR spectrum of each unknown will be provided.
• NMR spectrum of each unknown will be provided.
• Download and bring the datasheet to lab.

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In Lab

• No talking
• Record all data, observations, calculations and
  results in notebook
• Determine physical properties
• Correct observed data
• Perform solubility test
• Interpret IR and NMR spectra
• Be sure to bring calculators and your textbook.
  You will need the textbook for spectral
  information (back cover) and the list of unknowns
  in Ch 10. You may NOT use your textbook to
  reference procedures that should have already
  been recorded.

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In Lab

• Identify unknown based on all available data
• Tables 10.1 (pages 288-289)
• No Dienes
• Complete datasheet
• Turn in datasheet, annotated spectra, and
  notebook pages
• Everything is due at the end of the period.