CHM 266 Spring 2008 Organic Chemistry Lab

Experiment 1 Cysteine to Cystine

Note the point deductions and the total worth of various parts of the report is given. I reserve the right for further deductions for errors or omissions that shouldn’t be made in a 2^nd year laboratory course.

A. Turn in your sample in a labeled bottle. Include

· Compound Name

· Your name

· Date

· Weight of Product

· Tare Weight of Bottle

· NFPA #'s

· Decomposition Pt.

· The yield will be worth 5 pt. Sample weights that are off by > .05 g. will lose 0.5pt. Sample weights that are off by > 0.1 g. will lose 1 pt. I will assume that you used no more than 0.02 g. of sample in your analysis. The point scale for the yields will be given after the samples are turned in.

Yield Scale out 5 points. Of course adjustments will be made if you started out with more or less than the stated amount of limiting reagent.

Your yield in grams	Value in points
> 0.5	5
> 0.45	4.9
> 0.4	4.6
> 0.35	4.2
> 0.3	3.8
> 0.25	3.3
> 0.15	2.5
> 0.1	2.1
< 0.1	1.7

· The decomposition point will be worth 3 pt. The point scale for dec. pt. will be given after samples are turned in.

Your Dec. Pt. °C	Value in points
> 233	3
> 230	2.7
> 220	2.5
< 220	2

Please fill out the report in the following order

B. Your Name (-0.5 pt. if missing)

C. Date (-0.5 pt. if missing)

D. Experiment Title and Number (-0.5 pt. if missing)

E. Write the procedure in a journal style format. Use the 2 examples given at the end of this report form. Note how IR data is reported in journal format. The procedure will be worth 6 pt. The following deductions will be applied

· No yield stated in procedure -0.5 pt.

· No % yield given procedure -0.5 pt.

· Incorrect yield calculation -0.5 pt.

· Dec. pt. not given in procedure -0.5 pt.

· IR data missing in procedure -0.5 pt.

· Any unclear or incorrect statements (-.3 pt. each)

· Spelling errors particularly for compounds, techniques, apparatuses, and instruments (-0.2 pt. each)

· Overall report is not typewritten (-2 pt.).

F. Answer the following questions.

1. (1 pt.) Based on your IR spectrum, is your final product the free amino acid, the hydrochloride salt, or the sodium salt? You must determine this form your IR spectrum. It is not likely that all the IR bands will fall exactly in the ranges listed in the notes. No explanation is required.

2. (2 pt.) Answer question 1 on p. 908 of the lab manual.

G. Staple IR spectrum to end of report. (3 pt. possible deductions for poor quality)

Procedure in journal format: In any field, research is reported in a scholarly journals using specific formats. These formats are often so common and useful that even reports to research advisors, group leaders, and “bosses” in technical fields request them for weekly/monthly reports. We will use the format used for reporting procedures in organic chemistry. It is different from your notebook. Notebooks try to provide as much information as possible. Journals try to be concise. Their procedures provide just enough information to repeat the experiment. An example follows for a different chemical reaction. Modify your procedure to fit this format. Notice that you are asked to report yield (# of grams of product) and % yield. This means that you will need to determine the limiting reagent, calculate the theoretical yield and then finally the % yield. (O.N. means overnight.)

N-Methoxy 4-acetylbenzenesulfonamide

2.0 g. (8.9 mmol) 4-acetylbenzenesulfonyl chloride was added to a mixture of 5.5 ml. pyridine and 0.83 g. (10.0 mmol) methoxyamine hydrochloride cooled with an ice bath. After the addition was complete, the mixture allowed to warm to room temperature and stirred O.N. Solvent was removed en vacuo, and 33 ml. of water was added to the residue and stirred for 1 h. 30 ml. of CH₂Cl₂ was added to the mixture which dissolved the gummy yellow solid present. After separating the layers, the aqueous phase was washed with another 30 ml. of CH₂Cl₂. The combined organic layer was dried over MgSO₄ and the solvent was removed en vacuo. 0.14 g. (6.7%) white powder from methanol. m.p. 165 - 167° C. IR 3219, 2982, 2942, 2903, 2818, 1663, 1597, 1398, 1345, 1277, 1171, 1049, 927 cm^-1.

4-Acetylbenzenesulfonamide

0.9 g. (4.2 mmol) 4-Acetylbenzenesulfonyl chloride and 26 ml. conc. ammonia were heated to reflux for 20 min. and then stirred for 1h. The solid was collected by vacuum filtration and washed with water. 0.59 g. (70.2%) pale yellow crystals from ethanol. m.p. 177.5 - 179° C. IR 3310, 3098, 1669, 1401, 1343, 1267, 1160, 1096, 841, 784, 641 cm^-1.

This Table must be completed in your notebook.

Table of Compounds

Compounds	MW	Amount (g or mL)	Amount (mol)	mp	bp	General Hazardous
L-(+)-Cysteine hydrochloride monohydrate
Hydrogen Peroxide
Sodium Hydroxide
Cystine		^1,2	^1,2	³

¹Theoretical Yield ²Actual Yield ³Decomposition point: