Chemistry 319, Organic Chemistry Laboratory, Fall 2011

Textbook: "Organic Laboratory Techniques", 3rd. ed.,by Fessenden, Fessenden and Feist.
"Laboratory Manual for Organic Chemistry, 319" (Available at El Corral).

Materials:

Safety Goggles (Z-87 rated) and a pair of Rubber Gloves (not surgical type)
Protective Apron will be provided
Bound Laboratory Notebook, Spectral Notebook and a Lock for your drawer

Safety:

At all times while you are in the laboratory, you must wear your goggles and protective apron. While you are in the organic chemistry laboratory, the foremost thought in your mind should be safety. You are expected to work at a steady pace, but under no circumstance should you rush and create a hazard for yourself or your classmates. Be certain to prepare carefully before coming to the laboratory.

The Laboratory Notebook:

Purchase a hard bound notebook with lined format and prepare it by writing page numbers in all of the upper right hand corners beginning with 1,2,3, etc. You will treat the left hand page, or the back of each page as you may prefer to view it, as a place for note taking and calculations. The left hand pages are substitutes for paper towels or loose note paper. Your organized laboratory material will be placed on the right hand pages. Save the first 2 right hand pages for the table of contents. Remember that all entries are to be in ink. Place a single line through any mistakes. Don't try to erase or use a White-Out material.

* Experiment Title and Date
* Reference
* Reaction Equation
* Materials
** Procedure (the procedure should be detailed enough that someone could pick-up your lab book and perform the experiment without additional information).
*** Organization of Results and Conclusions (In your conclusion be sure to answer the following questions for each experiment: What was your percent yield? Did you get what you wanted? How do you know? Was it pure? How do you know that?)

* Do this part of your book before coming to the laboratory.
** Make these entries while you are in laboratory.
*** Make these entries when you have time at the end of your procedure.

The Spectra Book

1) A small two or three ring flat binder is needed.

2) The spectra book must have a table of contents.

3) In addition to taking the spectra, they must be interpreted. Draw the structure of the product on the center of the NMR and with arrows, show where the pieces of the molecule are located on the spectrum. For the IR spectra, with arrows show the appropriate absorptions (e.g. C=O, C=C).

Sample Page from a Lab Book

Synthesis of Ethyl Acetoacetate Acetal

Reference: G.F. Moran, J.Chem. Educ., 1973, 50, 216.

Procedure:

21 September 2011

16:30 - On top of a 100mL round bottom flask was placed a three-way adapter. With a Kem-Klamp a 25 ml round bottom flask was attached to the side-arm. A condenser was placed on top of the adapter with a reflux condenser. To the round-bottom flask was added the ethyl acetoacetate, ethylene glycol, p-toluenesulfonic acid, and 50 ml of toluene. Another 20 mL of toluene was added through the condenser to fill the 25 ml round bottom.

16:45 -With a Thermowell the mixture was vigorously refluxed for 60 minutes.

17:45 - The mixture was allowed to cool to room temperature, capped with a cork and allowed to sit in the drawer until the next period.

26 September 2011

15:15 - The mixture was transferred to a separatory funnel, and washed with 15 mL of 10% sodium hydroxide solution, followed by 2 x 20 mL portions of water.

16:15 - The organic layer was then dried with anhydrous potassium carbonate, filtered and concentrated at the rotary evaporator to give 17.3 g of a light yellow oil.

16:45 - The residue was transferred to a 50mL round bottom flask, a magnetic stir bar was added, a Claisen adapter attached, and vacuum distillation assembly completed.

17:30 - The material was distilled under vacuum (92-95oC, 1.5mmHg) over a period of 35 minutes, and 15.2 g of product was collected.

28 September 2011

15:30 - A refractive index was measured and IR and NMR spectra were taken.

Results and Conclusion: 15.2 g (87%) of product was obtained. The material appeared to correspond to the expected product. This was evidenced by comparison to the literature value for the refractive index (observed 1.4332, literature 1.4339). The IR spectrum showed that the starting material had been consumed as evidenced by the disappearance of the ketone carbonyl at 1710 cm-1. The NMR spectrum was clearly in support of the expected structure. 4.1d (q, 2H), 3.6d (s, 4H), 2.8d (s, 2H), 1.6d (s, 3H), 1.3d (t,3H). The new peak at 3.6d corresponding to the ketal's CH2's was pronounced. In addition, the location of the singlets at 2.8 and 1.6d are indicative of the correct product. In general the experiment went favorably. There was a pot residue, 3.6 g, from the distillation but it was not analyzed.

Products:

Don't throw away any materials that you produce. Any material that you prepare or purify will be turned into to me. It will be necessary to place the sample in a screw-cap vial with a label describing the contents. On each label I want the following information:

experiment name	structure of product	your name
theoretical and actual mass	percent yield	physical property

Grading:

Plus/minus grading will be used. The average lab grade is usually the letter grade, B.

15% Lab Book [periodic unannounced checks] (average 13/15)
15% Spectra Book [periodic unannounced checks] (average 12/15)
20% Products [purity and amount] (average 17.5/20)
15% Midterm & Final [at weeks 6 (5/3) and 10 (6/2)] (average 11/15)
15% Amine Unknown & Beilstein Report (average 14/15)
20% Personal Estimate (average 16.5/20)

Useful Websites:

http://www.chemfinder.com (For chemical structure and physical property searches).
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_index.cgi?lang=eng (Excellent source for viewing and downloading IR, HNMR, ¹³CNMR and mass spectra - search recommended by molecular formula and query).
http://www.mdl.com (After login and registration at this site, go to dowloads for a free ISIS/Draw in Mac or Windows versions).
http://scistore.cambridgesoft.com/sitelicense.cfm?sid=797 (Free download of ChemDraw Std 11.0 is currently unavailable).
http://hazard.com/msds/index.php (University of Vermont archive of material safety data sheets).
http://www.sigmaaldrich.com/ (Catalog of chemical supplies including useful physical properties, IR, HNMR,
¹³CNMR and mass spectra, and some MSDS information. Use Product Search).
http://webbook.nist.gov/ (An additional site for IR, UV, mass spectra and other chemical information).

Use of Grease on Ground Glass Joints:

A) When do you need to use it?

Evolution is a curious phenomenon. At one time, Bunsen burners were frequently used to heat mixtures of organic materials. With the development of efficient electrical sources of heat and the use of Teflon as a material for stopcock valves, etc., the use of grease to seal ground glass joints has fallen far to the wayside. There are however, two legitimate times when grease should be used.

1. When you are attempting to create a vacuum seal for your apparatus, you must use grease (e.g., in a vacuum distillation, or on permanent fixtures of the rotary evaporator or a similar apparatus).
2. Grease must also be used when you have created a basic reaction mixture. Base is notorious for causing ground glass joints to fuse. This concern over basic reaction mixtures applies not only to solutions containing common bases such as sodium hydroxide, but also to those containing alkoxides and hydrides.

If you develop the good habit of not using grease, remember to use it when it is essential.

B) Why should the use of grease be restricted?

Most greases used for ground glass joints are soluble in organic solvents. This means that the grease will eventually work its way into your solvents, and into your final product. You will not find an experimenter who is accustomed to working on small scale, use grease, except in the instance of vacuum distillation or vacuum transfer. Teflon tape is sometimes used in place of grease for small-scale reactions. On larger scales, washing grease into your solvent and eventually into the product is common, although somewhat less annoying.

C) Keep your ground glass joints clean and sparkling.

We commonly remove grease with solvents such as ligroin (30-60), hexane, or dichloromethane. A ground glass joint can be dipped into a small beaker of one of these solvents and wiped quickly with a Kimwipe before drying (Use your gloves!). The resultant is an opaque joint surface.

When using grease for a reaction, be certain to remove it before attempting to pour your contents out of the flask. Wipe the bulk of the grease away with a dry Kimwipe, then use a Kimwipe wet with one the degreasing solvents to remove the remainder of the grease (Use your gloves!). Remember that small amounts of materials can best be removed from flasks with disposable pipettes, rather than by pouring.