Hey! Finally was able to isolate the dimethly ether of gallacetophenone. Here is what the TLC looked like
Apparently the reactant (right in the tlc) has converted almost completely to the product. The reaction conditions were as follows :
3.36 gm of gallacetophenone(0.02 moles) and 15.8 gm (0.1 mole) was added in 100 ml acetone and refluxed for 20 mins. The reaction mixture was cooled to room temperature. To this, 2.52 grams(0.02 moles) of dimethyl suflate was added and stirred for 3 hours. The reaction did not seem to progress. So the reaction was heated for about 1 hour at reflux. The reaction flask was kept under free stirring for 48 hours and the TLC shown above was taken. Apparently the reaction had proceeded. The spot with the reactant is almost gone. There is a faint spot of the mono methyl ether just below the main dark spot. The trimethyl ether is seen distinctly above the monomethly ether.
Workup : The acetone was distilled off to leave only 10 % of the solution. To this about 50 ml toluene was added and the reaction mixture was washed with almost 100 ml (25ml x 4) of 20% NaOH. This was done so that only the mono and di methly ethers would remain in the solution. These were then to be separated by column chromatography. Hope you guys find it useful 
Today was a good day! I learned a lot from the research reactions that I have been carrying out. Its really a great learning exprience. Okay, today what I did was methylation of my product that I have synthesized earlier. I have described the product synthesis here. Let me call the reactant “A”. Okay, here is what I did. I took up 5 ml of acetone in a test tube. I took about 0.5 g of “A” in the test tube. The compound got dissolved and formed a light yellow solution. To that, about 0.2 g of K2CO3 was added. This resulted into a little bit of extra K2CO3 remaining undissolved. The test tube was shaked vigorously and I tried to make sure that the K2CO3 dissoved as much in the reaction mixutre as possible. After about 5 minutes of vigorous shaking and breaking of K2CO3 with a glass rod, quite a bit of K2CO3 had dissolved. After that about 0.2 ml of methyl iodide was added to the reaction mixture. This resulted into deepening of the yellow colour of the reaction mixture. The temperature of the test tube rose by about 1 C. I will check the results of the tests by tomorrow. Hopefully, it would give me something to cheer about!
Here pyrogallol reacts with Acetic Anhydride in presence of Zinc Chloride (Lewis Acid) and acetic acid as a solvent.
Pyrogallol:
- IUPAC Name: benzene-1,2,3-triol
- Chemical Formula: C6H6O3
- Exact Mass: 126.03
- Molecular Weight: 126.11
- m/z: 126.03 (100.0%), 127.04 (6.7%)
- Elemental Analysis: C, 57.14; H, 4.80; O, 38.06
- Boiling Point: 309°C
- Melting Point: 131-134 °C
- Critical Temp: 792.92 [K]
- Critical Pres: 99.8 [Bar]
- Critical Vol: 311.5 [cm3/mol]
- Gibbs Energy: -342.18 [kJ/mol]
- Log P: 0.87
- MR: 30.72 [cm3/mol]
- Henry’s Law: 12.61
- Heat of Form: -451.1 [kJ/mol]
- tPSA: 60.69
- CLogP: 0.211
- CMR: 3.1479
Gallacetophenone:
- IUPAC Name: 1-(2,3,4-trihydroxyphenyl)ethanone
- Chemical Formula: C8H8O4
- Exact Mass: 168.04
- Molecular Weight: 168.15
- m/z: 168.04 (100.0%), 169.05 (8.9%), 170.05 (1.2%)
- Elemental Analysis: C, 57.14; H, 4.80; O, 38.06
- Boiling Point: 705.05 [K] (Calc)
- Melting Point: 171-172 °C
- Critical Temp: 828.83 [K]
- Critical Pres: 76.28 [Bar]
- Critical Vol: 429.5 [cm3/mol]
- Gibbs Energy: -463.89 [kJ/mol]
- Log P: 0.18
- MR: 41.97 [cm3/mol]
- Henry’s Law: 15.35
- Heat of Form: -616.43 [kJ/mol]
- tPSA: 77.76
- CLogP: 0.861434
- CMR: 4.1112
Synthetic Procedure:
In a 250-cc. round-bottomed flask, fitted with a reflux condenser, 28 g. (0.21 mole) of freshly fused zinc chloride is dissolved in 38 cc. of glacial acetic acid by heating in an oil bath at 135–140°. Try to make sure that the quality of Zinc Chloride used is good. It is always preferred to freshly fused Zinc Chloride. The temperature of the solution remains close to about 132 °C. Once the temprature reaches this point, forty grams (0.37 mole) of 95 per cent acetic anhydride is then added to the clear, pale brown liquid, followed by the addition in one lot of 50 g. (0.4 mole) of distilled pyrogallol. The addition should be done only after about 30 minutes of free stirring of pale brown liquid. The mixture is heated at 140–145° (Note 3) for forty-five minutes with frequent and vigorous shaking. Once again, due to the acetic acid synthesized in the reaciton, the temprature of the flask should not exceed 138 °C. You can try to maintain the bath temperature at 150°. The unused acetic anhydride and acetic acid are removed by distilling under reduced pressure. The temperature should NOT exceed 150 °C. The red-brown cake is broken up by the addition of 300 cc. of water with mechanical stirring for a few minutes. The mixture is cooled in ice water, filtered with suction, and washed with cold water. The crude material, 45–50 g., is crystallized from 500 cc. of boiling water saturated with sulfur dioxide. The yield of straw-colored needles melting at 171–172° is 36–38 g. (54–57 per cent of the theoretical amount). On saturating the mother liquor with salt and cooling to 10°, 4–5 g. of crude material is obtained, which on recrystallization yields 3–4 g. of pure material.
The method described above is a modification of the process of Nencki and Sieber. Gallacetophenone has also been prepared by treating pyrogallol with acetyl chloride, and from 2-formyl-4-acetylresorcinol by treatment with hydrogen peroxide and alkali.
Related References:
- Witt and Braun, Ber. 47, 3227 (1914).
- Cheema and Venkataraman, J. Chem. Soc. 1932, 919.
- Nencki and Sieber, J. prakt. Chem. (2) 23, 151, 538 (1881);
- Nencki, Ber. 27 2737 (1894).
- Crabtree and Robinson, J. Chem. Soc. 121, 1038 (1922).
- Einhorn and Hollandt, Ann. 301, 107 (1898);
- Fischer, Ber. 42, 1020 (1909).
- Nakazawa, J. Pharm. Soc. Japan 59, 297 (1939) [C. A. 33, 8186 (1939)].
