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The Synthesis of D,L-Phenylglycine and Its Optical Resolution

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Academic year: 2021

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(1)

Experiment 1

The Synthesis of D,L-Phenylglycine and Its Optical Resolution

Total Scores: 100 points

1-1 1-2 1-3 1-4 1-5 ∑

Total Points 25 15 25 5 30 100

Received

Step 1. Preparation of (D,L)-phenylglycine

1-1 Confirmed and signed

by lab assistant

Weight of benzoylformic acid used: g g

/

Weight of fritted glass funnel: g g

/

After complete dryness:

Product weight + fritted glass funnel: g g

/

[Weigh on a balance that reads to the nearest centigram (0.01g)].

Weight of D,L-phenylglycine obtained: g Chemical yield: %

Calculate the chemical yield (% yield; show the calculations).

Recommended scoring standard:

(2)

We will double check the calculations, 5 points will be taken off for the wrong calculations. Points will be given based on the correct chemical yield.

1-2

Turn in the sample (in the vial with blue label).

Signature of student:

Signature of the lab assistant:

[The organization committee will weigh an appropriate amount of sample (0.01g) for 1H NMR spectroscopic analysis.]

Recommended scoring standard:

Impurity may come from the ammonium formate and unknown side products. From our pilot studies, most students will be able to get 15 points.

Step 2. Optical resolution of D,L-phenylglycine by (+)-camphorsulfonic acid [(+)-CSA]

1-3 Confirmed and signed by lab assistant

Weight of D,L-phenylglycine used: g g

/

(3)

After complete dryness:

Product weight + fritted glass funnel: g g

/

[Weigh on a balance that reads to the nearest centigram (0.01g)].

Weight of the resolved phenylglycine • (+)-CSA salt: g Chemical yield: %

Calculate the chemical yield (% yield; show the calculations).

Recommended scoring standard:

We will double check the calculations, 5 points will be taken off for the wrong calculations. Points will be given based on the correct chemical yield.

1-4

Draw the correct configuration formula (stereochemical structure) of the isolated phenylglycine.

O NH2

OH

NH2 COOH H

O Ph NH2

H OH

If only correct chemical structure is given (no stereo chemistry), 1 point is given.

(4)

1-5

Specific rotation of the enantiomeric phenylglycine • (+) CSA salt (to be determined by the organization committee)

Turn in the sample (in the vial with pink label).

Signature of student:

Signature of the lab assistant:

[The organization committee will weigh an appropriate amount of sample (0.055 ~ 0.065g) for measurement of optical purity.]

Recommended scoring standard:

The organization committee will weigh the resolved product (from the fritted glass funnel) for students who fail to finish the procedure in time. However, 15 penalty points will be taken.

(5)

Experiment 2

Identification of Unknown Inorganic Samples

Total Scores: 100 points

2-1 2-2 ∑

Total Points 96 4 100

Received 2-1

Unknown Compound

Code Number**

Unknown Compound

Code Number**

Unknown Compound

Code Number**

HCl , H2SO4 , NH4SCN , NaOH , BaCl2 , K4Fe(CN)6 , Na2CO3 , ZnCl2 ,

Na2SO3 , H2O2 ,

**Second column is for duplicates.

2-2

A. Write the electrolysis equation that would help you confirm that an unknown sample is ZnCl2. Zn2+(aq) + 2Cl—(aq) → Cl2(aq) (anode) + Zn(s) (deposit on cathode)

B. Write one equation that shows how to clean the deposit of Zn on the electrode (limited to the items provided in this task).

Zn(s) + 2H+(aq) → H2(g) + Zn2+(aq) or Zn(s) + 2OH—(aq) → H2(g) + ZnO22—(aq)

Riferimenti

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