Hand in Lecture Problem 6

1
Lecture 17

• Hand in Lecture Problem 6
• The Synthetics
• Quiz 6 Review
• Reminder Quiz 6 in lecture on Thursday Hand in
  Selection Sheet!

• This Week in Lab
• Finish Ch 9
• Ch 7 Final Report Due
• Ch 12 Progress Check
• Next Week in Lab
• Start synthetics!
• Synthetic 1 PreLab Due
• Ch 9 Final Report due the week of April 10th!

Note This weeks office hours are from 1 to 3
pm on Wednesday.
2
Natural Product Isolations
Experiment 110 Cholesterol from Human Gallstones

• Extraction of cholesterol from gallstones using
  hot solvent
• Analyses IR, NMR or MS
• Cholesterol Attached to lipoproteins HDL and LDL
  
• Average human has 200 g of cholesterol located
  in spinal cord, brain, and nerve tissues
• May produce gallstones or cause hardening of the
  arteries

3
Natural Product Isolations
Experiment 112 Isolation of Casein, Lactose
Albumin from Milk

• Casein a phosphoprotein
• Albumin a globular, water-soluble protein
• Lactose a carbohydrate
• Techniques used to isolate these 3 biomolecules
• Precipitation of casein
• Separation of lactose albumin by
  centrifugation
• Analyses Polarimetry of lactose

4
Natural Product Isolations
Experiment 116 Soap from Nutmeg

• Isolate trimyristin from nutmeg
• Saponify trimyristin to form sodium myristate, a
  soap
• Saponification hydrolysis of an ester
• Analyses chemical tests and IR or NMR

5
Reduction Reactions
Experiment 130 Hydrogenation of Olive Oil

• Reduction of CC bonds
• Quick look at mechanism in class
• Analyses IR NMR

6
Reduction Reactions
Experiment 135 Enzymatic Reduction A Chiral
Alcohol from a Ketone

• An asymmetric reaction!
• Quick look at a similar reduction mechanism in
  class
• Analyses Polarimetry with IR or NMR

7
Substitution Reactions
Experiment 142 Synthesis of a Plant Hormone

• SN2 mechanism!
• Analyses IR, NMR MS
• 4-Chlorophenoxyacetic acid (2)
• Plant growth hormone
• Promotes growth of roots on plant clippings
• Prevents fruits from falling prematurely

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Substitution Reactions
Experiment 144 Synthesis of OFF

• Two-step process
• Make the acid chloride (mechanism not needed)
• Make an amide from the acid chloride (acyl
  substitution reaction)
• Analyses IR, NMR, or GC/GC-MS
• N,N-diethyl-m-toluamide (OFF)
• Insect repellent

9
Substitution Reactions
Experiment 145 Synthesis of Norleucine

• SN2 reaction - substitute Br with NH2
• Analysis IR
• Norleucine
• Not a naturally occurring amino acid
• Structural isomer of leucine and isoleucine
  (both essential AAs)

10
Substitution Reactions
Experiment 146 Synthesis of Sulfanilamide

• Two substitution reactions plus a hydrolysis
• Analyses Bioassay with IR or NMR
• Sulfanilamide
• Inhibits growth of folic acid thus stopping the
  growth of bacteria

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New PreLab Sections Chromatographic Spectral
Features Comparisons

• For the synthetic experiments only! See Chapter
  10 for details!
• Chromatographic Comparison
• Relative Rf comparison between main organic
  starting material and main
• product of reaction.
• Example

(Draw out structures)
Cyclohexanol would have a lower Rf value due to
the OH functionality, which is more polar than
the alkene of cyclohexene.
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PreLab Sections Chromatographic Spectral
Features Comparisons

• For the synthetic experiments only!
• Spectral Features Comparison
• Consider diagnostic 1H NMR IR signals for the
  starting material and product
• that would be used to distinguish the two from
  one another.
• Example

(Draw out structures)
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Comments on Synthetics

• May need to repeat an experiment.
• Yields count! The quality of your technique
  will be
• evaluated.
• Check Chemical Inventory when looking for
  chemicals check
• hooded shelf, common shelf, refrigerators, ask
  class/TA,
• or ask stockroom
• Get melting points for all solid products.
  Report yields for
• all products.
• Do TLC analysis for appropriate reactions. TLC
  charts posted
• throughout labs.

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Troubleshooting

• No product formed
• No reaction - recovered starting material
  verify by TLC
• Check reagent bottles
• Check times and temperatures
• Check calculations
• Low yield after recrystallization
• Added too much solvent? Concentrate solution.
• Obtain an oily-non-crystalline product? Try to
  recrystallize
• product to get a solid.

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Quiz 6 Review

• Questions on
• Basic theory of IR NMR
• Data interpretation of IR NMR data
• May include annotating data
• Solving unknown structures using data
• IR NMR correlation charts will be provided.
• Look over old lecture problems and lab
  guide/McMurry problems.

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Spectroscopy

• NMR (Nuclear Magnetic Resonance Spectroscopy)
• Uses radio waves (electromagnetic radiation)
• Interacts with samples nuclei in the presence of
  a magnet
• Effect nuclei flip and relax (known as resonance)

1H NMR Determine bond connectivities/pieces of a
structure, whole structure

• IR (Infrared Spectroscopy)
• IR radiation
• Interacts with molecule as a whole
• Effect bond vibrations within molecule

IR Use Determine the functional groups present
in a structure -OH, CO, C-O, NH2, CC, C?C,
CN, C?N
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Quiz 6 Practice Problems
Propose a structure that is consistent with the
following data. C4H7BrO2 1H NMR IR 1.08
ppm (t, 3H) broad peak 2.07 ppm (m, 2H)
2500-3000 cm-1 4.23 ppm (t, 1H) peak at 1705
cm-1 10.97 ppm (s, 1H)

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Quiz 6 Practice Problems
C7H8O 1H NMR IR 2.43 ppm (s, 1H) broad
peak in 3200- 4.58 ppm (s, 2H) 3500 cm-1
region 7.28 ppm (m, 5H)