Acetic Acid and Percentage Yield Essay

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Experiment #5B: Macrocyclic Synthesis
Nathan Cordova, Stefanie Lopez, & Lonny Nenadovich
March 26th, 2015
Pima Community College - West Campus

Authors Note
Laboratory Report for Organic Chemistry II, 235IN, taught by Dr. Medeiros Macrocyclic Addition
Nathan Cordova, Stefanie Lopez, & Lonny Nenadovich
Instructor: Dr. Matthew Medeiros

Purpose/Aim: The macrocyclic molecules, TPP and TPP cobalt(II) complex, were synthesized and all products were analyzed using UV/Visible light spectroscopy. Synthesis of TPP yielded 0.129 g; a percentage yield of 8.57%. The synthesized amount of TPP cobalt(II) complex was 0.387 g; percentage yield of 353%. There was major product loss and error. Maximum wavelengths recorded for TPP and the metal complex were 418 nm and 417 nm respectively. The TPP cobalt(II) complex was concluded to have a higher energy band gap than TPP due to a slightly smaller maximum wavelength.

To understand how synthesis of macrocylic synthesis or heme analog works, the objective of today’s lab is to synthesize meso-Tetraphenylporphyrin (TPP) from benzaldehyde, pyrrole, and an addition of acid. Then use the TPP product to synthesize a TPP metal complex of either cobalt (II), copper (II), or zinc. Porphyrins are able to form complex metal ions and are comprised of a macrocylic, nitrogen-containing rings. They are found in hemoglobin and myoglobin which play important roles in bodily functions. TPP and the TPP metal complexes result in colored solid; therefore, UV/Visible light spectroscopy will be the analytical method to determine the spectrum for each compound and determine the maximum wavelength.

Method / Experimental Procedure:
Preparing meso-Tetraphenylporphyrin:

1) We measured out 40 mL of propanoic acid using a graduated cylinder
2) We placed the propanoic acid into a 250 mL round-bottom flask. Boiling chips were added thereafter.
3) Connect to reflux condenser.
4) Solution was heated up with the lab apparatus (heating mantle).
5) 0.7 mL of pyrrole and 1.0 mL of benzaldehyde was added through the condenser.
6) We continued heating for 30 minutes.
7) Solution was cooled to room temperature after 30 minutes.
8) A filtration system was set up using Buchner filter, a hose, and one-arm flask.
9) Filter solution through and apply suction.
10) If needed, filter the solution twice. Make sure the one-arm flask is clean!
11) The product was washed with methanol until washings are colorless.
12) Using suction the product was allowed to dry

Preparing TTP Copper, Cobalt, or Zinc Complex:
1) We obtained a 25 mL erlenmeyer flask and add a few boiling chips. Place 10 mL of DMF.
2) We heated the flask on hotplate until solvent begins to boil.
3) We added 100 mg of TPP to the hot DMF allowing it to dissolve.
4) 40 mg of copper(II), cobalt (II), or zinc acetate was added.
5) The solvent was heated at boiling point for 5 minutes.
6) Using as ice bath the reaction flask was cooled for approximately 15 minutes.
7) The mixture was diluted with 10 mL of distilled water.
8) Buchner filtration system was cleaned and the solid collected. Afterwards we washed it with water.
9) Using suction the product was allowed to dry

TPP Synthesis:
Starting materials => 0.7 mL of pyrrole, 40 mL of propionic acid, 1.0 mL of benzaldehyde
TPP yield => 0.129 g
Percentage yield => 8.57%

TPP UV/Visible light spectrum => maximum wavelength: 418 nm at 0.196 absorbance

TPP Cobalt(II) Complex Synthesis:
Starting materials=> 0.1 g TPP (product from first synthesis), 0.041 cobalt(II) acetate, 10 mL DMF
TPP Cobalt(II) Complex yield => 0.387 g
Percentage yield => 353%

TPP Co(II) complex UV/Visible light spectrum => maximum wavelength: 417 nm at 1.396 absorbance

The synthesis of the macrocyclic molecule, meso-tetraphenylporphyin (TPP, was performed followed by synthesis of TPP cobalt (II) complex from the TPP product and cobalt (II) acetate. TPP complexes typically are highly