Macrocyclic Synthesis Report

Prelab 5B Macrocyclic Synthesis

OBJECTIVE:
The objective this week is to produce Tetraphenylporphyrin and its metal complex. This will be carried out by condensation of 4 equivalents of Benzaldehyde and pyyrole in the presence of propanoic acid. The product will undergo UV/Visible Spectrum tests to determine its lambda max. The lambda max will show us the relationship between a conjugated system and the visible spectrum.

PROCEDURE:
Step 1: preparation of meso-tetraphenylporphyrin (TPP)
1. Set up reflux apparatus: -Add 40 mL of propanoic acid to 100 mL RBF with boiling chips -Attach claisen head to RBF with metal clip -Attach side arm of claisen head to reflux condenser -Attach blue cap and septum to straight arm of claisen head
2.
Simultaneously add .7 mL (.68g, 10 mmol) of pyrrole and 1.0 mL (1.05g, 10mmol) benzaldehyde through the condenser with graduated syringes.
3. Continue to heat at reflux for 30 min.
WORK-UP
1. Cool mixture to room temp. “if low crystals, can add a little methanol and cool”
2. collect colored product by suction filtration, filter twice if needed
3. wash with methanol until it runs clear, then dry for several minutes.
4. determine percent yield (weight), record UV/Visible spectrum (CHCL3) and determine lambda max.
Step 2: Preparation of TPP Copper Complex
1. Place 10mL of N,N-dimethylformamide (DMF) in a 25mL Erlenmeyer flask with boiling chips and heat on hotplate until slight boil.
2. Add 100 mg (0.16 mmol) TPP to the hot DMF, and dissolve
3. Add ~40 mg (0.20 mmol) of Copper (II) acetate, continue to heat at reflux for 5 min.
WORK-UP
1. Cool mixture in ice bath for 15 min then dilute w/ 10mL of distilled water.
2. Use a Buchner funnel and filter slowly the mixture. Wash with distilled water.
3. Collect small sample to run the UV/Visible spectrum in chloroform and determine the lambda max.
4. Weigh and calculate percent yield, save product in petri dish or beaker.

Physical Constants:
Compound
Mw(g/mol)
Mp©
Bp©
Density
Safety
Propanoic acid
74.07854
-21
141
.993g/mL
Toxic, Irritant
Pyrrole
67.09
-23
129-131
.9670g/cm3
Toxic, Central nervous system depression
Benzaldehyde
106.12
-26
178-179
1.044g/cm3
Toxic, Irritant
Methanol
32.04
-98
64.7
.7910g/cm3
flammable
Chloroform (CHCL3)
119.38
-63.5
61
1.489g/cm3
Flammable, toxic
N,N-dimethylformamide (DMF)
73.09
-61
153
.944g/mL
Irritant, Toxic
Tetraphenylporphyrin (TPP)
614.74
>300
N/A
1.27g/cm3

Copper (II) Acetate
181.63
115
240
1.88g/cm3
Irritant, Toxic
Cobalt (II) Acetate
249.08
100 Decomposes
N/A
N/A
Irritant, Toxic
Zinc (II) Acetate
219.5
237 Decomposes

1.74g/cm3

TPP Copper complex
671.65
>300

Brown crystal/powder λmax 411 nm

λmax 536 nm (2nd)