In addition to the table, please provide answers to the following questions: 1)

Question

In addition to the table, please provide answers to the following questions: 1) Evaluate the IR spectrum of the product (IR: page 99 in the Lab Manual). Comment on the key peaks for the product and how IR can be used to distinguish the anhydride and carboxylic acid (presence and absence of peaks). 2) (a) Based on the results of your melting point comment on the purity of the product. (b) Comparing similar molecular structures of Cycloaddition Product (Day 1) and Hydrolyzed Product (Day 2), why is the melting point increased so much after hydrolysis? 3) (a) Based on the use of 0.4 g maleic anhydride in this experiment, how much 2,3-dimethyl-1,3- butadiene in mL should be added to achieve equimolar conditions? (b) Why is an extra amount of 2,3- dimethyl-1,3-butadiene important in this experiment? Show calculations 4) If the hydrolysis to the diacid is not complete, how could you separate the desired diacid from the unhydrolyzed anhydride by extraction?

Explanation / Answer

IR spectrum Analysis:-

prominent peaks

1)3091.26 cm-1,intensity=strong and very broad --> expected at 2500-3000cm-1 due to O-H stretching vibration

2)2960.19 cm-1 ,intensity =medium --->expected at 2950-2850 cm-1 for C-H stretch of CH3(methyl)

3)1719.42 cm-1,intensity =strong,--->expected in the range 1780-1710 cm-1 dueto C=O stretch

4)1614.56 cm-1,intensity=medium---->alkene C=C stretch ,expected at 1680-1600 cm-1

5)1527.18 cm-1,intensity =strong,---->CH3 bending

6)1133.98 cm-1,intensity =strong,----->alkene =C-H bending

To distinguish anhydride from carboxylic acid:

peaks for carboxylic acid

-intensity=strong and very broad --> expected at 2500-3000cm-1 due to O-H stretching vibration

-intensity =strong,--->expected in the range 1780-1710 cm-1 dueto C=O stretch

peaks for anhydride

-intensity =strong,--->ttwo peaks expected in the range 1830-1800 cm-1 and 1775-1740 cm-1 dueto C=O stretch

-No broad OH peak

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