Organic Chemistry Lab 315
This presentation is the property of its rightful owner.
Sponsored Links
1 / 13

Organic Chemistry Lab 315 Fall, 2013 PowerPoint PPT Presentation


  • 122 Views
  • Uploaded on
  • Presentation posted in: General

Organic Chemistry Lab 315 Fall, 2013. DUE DATES. Today At beginning of lab – Identification of an Unknown Report Problem #1, Part II, Spectroscopy Problem Set At end of lab -- copy of laboratory notebook pages for today's experiment (do not turn in your pre-lab notes or in-class notes)

Download Presentation

Organic Chemistry Lab 315 Fall, 2013

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Organic chemistry lab 315 fall 2013

Organic Chemistry Lab 315

Fall, 2013


Due dates

DUE DATES

  • Today

    • At beginning of lab – Identification of an Unknown Report

    • Problem #1, Part II, Spectroscopy Problem Set

    • At end of lab -- copy of laboratory notebook pages for today's experiment (do not turn in your pre-lab notes or in-class notes)

  • Next Week

    • Part II, #2-5, Spectroscopy Problem Set

    • Extraction of Caffeine Report (see special instructions)


From last week

From Last Week

  • Pay attention to significant figures in calculations.

  • Properly labeled vial example in Pavia (page number was written on the blackboard). It must include the melting point range – you always report ranges (and it is an indication of purity).


In lab today

In Lab Today

  • Learn the new technique of extraction

  • Drying organic solvents (See p. 697 in Pavia)


Experiment notes

Experiment Notes

Beaker containing dissolved caffeine and insoluble binder

Funnel with glass wool as filter

Separatory funnel supported on iron ring on ring stand

Stopcock closed

Beaker underneath “just in case”


Experiment notes1

Experiment Notes

Beaker containing dissolved caffeine and insoluble binder

Funnel with glass wool as filter

Separatory funnel supported on iron ring on ring stand

Stopcock closed

Beaker underneath “just in case”

Separatory funnel with stopper

Aqueous layer on top

Methylene chloride layer on bottom (contains caffeine)

Drain off CH2Cl2 bottom layer into beaker

Total 3 extractions (8 ml x 3)


Experiment notes2

Experiment Notes

Extractions in a Separatory funnel

  • Add liquids using a glass funnel in order to not contaminate the neck of the sep. funnel

  • After replacing the stopper, turn the sep. funnel upside down to vent. Repeat if audible gas escapes.

  • Shake/swirl gently, but thoroughly, to mix the immiscible liquid phases. Emulsion may form in this experiment.

  • Caffeine is in the bottom CH2Cl2 layer. Drain bottom layer through stopcock into 100 ml beaker. [This is one extraction.]

  • Add additional CH2Cl2 with glass funnel from top.

  • Extract with CH2Cl2 three times total, combining all extracts in beaker.


Experiment notes3

Experiment Notes

There will be water dissolved in the CH2Cl2 extracts that needs to be removed.

Organic solvents are “dried” by using an anhydrous salt that can absorb the water and become hydrated.

See Section 12.9 in Pavia for common drying agents and equations for anhydrous salt → hydrated salt

MgSO4 + H2O → MgSO4∙10H2O

When you are ready to dry your solution, bring it to the instructor’s bench.

After drying, decant the solution into a pre-weighed beaker.


Experiment notes4

Experiment Notes

  • Evaporate solvent UNDER THE HOOD.

  • Do not recrystallize caffeine.

  • Weigh the beaker and mostly dry caffeine.

  • Place your caffeine in a properly labeled vial. See Pavia for an example of a correctly labeled vial.

  • Caffeine tablet contains 200 mg of caffeine. The remainder is “inert ingredients”.

  • Calculate the % isolation based on the mg caffeine in the 2 tablets.


Report for next week

Report for Next Week

  • Report Form in Manual

  • Separation scheme (flow chart of procedure for separating a pure product from reaction by-products)

    • See explanation and example in Manual/class web page

  • There is no written report required (major grading will be for the Separation Scheme – be sure you understand it)


Report for next week1

Report for Next Week

  • Some additives in Vivarin:

    • polyethylene glycol and polysorbate 80 (water-soluble)

    • titanium dioxide and silicon dioxide (water-insoluble)

    • D&C yellow #10 and yellow #6 aluminum lake (water-insoluble)

    • carnauba wax (water-insoluble)


Report for next week2

Report for Next Week

  • These additives should be included in your Separation Scheme for isolating caffeine from Vivarin tablets. You do not need to find the structures for these compounds.

  • You can ignore the effect of Na2CO3 on the water-solubility of any of these additives. (Na2CO3 was added to the Vivarin-water solution.)


  • Report for next week3

    Report for Next Week

    • Your Separation Scheme should resemble the one done for isolation of caffeine from tea leaves, shown in class.


  • Login