Lizz Radican Lab 4 2/24/14 The Diels-Alder Reaction: Results and Problems 1. ) Table 1: Mass, Percent Yield and Melting Points for Diels-Alder Reaction Products. Product Mass (g) Percent Yield Melting Points (°C) Anhydride 8. 87 88. 2% 164. 4-165. 8 Dicarboxylic Acid 3. 20 71. 9% 176. 6-180. 1 Unknown 1. 66 111% 168. 7-176. 0 2. ) See attached calculations. 3. ) Table 2: Anhydride Product IR Data: Functional Group or Bond Peak Location(s) (cm-1) Peak Intensity Symmetric C=O Stretch
1840 Weak Asymmetric C=O Stretch 1765 Strong C-O Stretch 901 Very strong Table 3: Dicarboxylic Acid Product IR Data: Functional Group or Bond Peak Location(s) (cm-1) Peak Intensity C=O Stretch 1702 Strong O-H Stretch 3200-2500 Broad, medium Sp2 C-H Stretch(s) 3021, 3082 Medium Table 4: Lactone (Unknown) Product IR Data Functional Group or Bond Peak Location(s) (cm-1) Peak Intensity O-H Stretch 3100-2500 Broad, medium C=O-O Stretch(s) 1175, 1158 Very strong C=O Stretch(s)
1769, 1691 Strong 4. The reaction of the unknown with bromine gave a negative result meaning the solution did not turn clear, but rather, maintained an orangish brown color. This is interpreted to mean that bromine in not adding to either side of an alkene bond, so there is no C=C bond in the unknown compound. The reaction of the dicarboxylic acid with bromine gave a positive result meaning that the solution turned clear as a result of bromine adding to both sided of the C=C bond.
The dicarboxylic acid has a C=C bond. Problems: 1. The carbonyl that is NOT incorporated into the ring structure has the greater IR stretching frequency. This is because the carbonyl incorporated into the ring structure shares some of its double bond character with the other double bond in the ring, giving it more single bond character. Thus, conjugated double bonds lower the stretching frequency of a carbonyl group by sharing the dipole character of the carbonyl group with the double bond.
The Review on Group Cohesiveness
We are thankful to a lot of people for all the cooperation and support they extended, without which this project would not have been possible. We are grateful to our Organizational Behaviour – II Professor Manish Singhal, for giving us the opportunity to work on this project, and for all his guidance in his course lectures. We are thankful to our teaching assistants Gaurav Marathe and Madhu ...
2. Some C=C groups sometimes do not show up on an IR spectrum. This is because the C=C groups of aromatic compounds show weak overtones between 1650-2000 cm-1. This area of aromatic overtones could be partially covered up by a strong C=O peak(s) over the same frequency range. An aromatic C=C stretch could also be hidden by a nitrile stretch or an alkene C=C. 3. Maleic anhydride is an excellent dienophile because it is a cyclic alkene where the double bond is conjugated to two carbonyl groups.
These groups, as well as the oxygen to which they are bonded, serves as a large electron withdrawing group which pulls electron density away from the double-bonded carbons. Because of this dipole effect, these carbons have a much more positive character, which will readily react with an available electron-rich diene. (See drawings on attached pages. ) 4. Yes, the reaction will be successful because the molecule possesses a conjugated diene that can rearrange through resonance where the double bonds localize to the same ring and react with a dienophile to form a bicyclo ring. 5. Drawings on attached pages.
