Here we will be attempting to prepare propiophenone via the distillation of a mixture of calcium

and propionic acid.

Here is the mixture of salts we prepared for the reaction which were in a 1 to 2 ratio

of propionate to benzoate.

As a quick background, we prepared the calcium benzoate through a reaction with solutions

of calcium chloride and sodium benzoate and collected the precipitate formed on cooling.

The calcium propionate was prepared by reacting the correct quantity of calcium hydroxide directly with propionic acid.

The mixture of salts was then dried again in a hot oven, ground to fine powder with a consistency of flour, and 110 grams of this mixture placed into a dry 500 ml round bottomed flask.

To begin with we put this in a heating mantel, and set up for simple distillation.

It took a lot of heat on the flask before, anything interesting happened.

As the flask got really hot, we saw smoke appearing, and we soon got a small amount of liquid distilling, over which had a vapor temperature of 85 degrees C, according to the thermometer and the still head.

After this we couldn't get the flask any hotter so, we took the mantel away, and heated the flask directly, using a gas flame.

The contents of the flask turned brown then black and, as the temperature increased, we noticed another batch of distillate, being produced which was yellow in color.

The heat was continued until no more distillate was produced.

Which took around 3 hours.

The result was around 35 ml of orange liquid, with a few drops of water sitting at the bottom.

This has a very strong petrochemical spicy aroma and is slightly irritating to the eyes.

We put the distillate into a separating funnel and washed thoroughly with 20 ml of water.

The water formed the bottom layer, but a slight emulsion, was formed which took a while to separate properly.

We washed again with another 20 ml of water, then, drained the water off, and retained the product.

We dried this using anhydrous magnesium sulfate and then set, up again for distillation in order to see what we've, got.

Our first fraction, came up to about 50 ml.

Over between 75 and 80 degrees.

See, we got about 6 ml of a colorless liquid.

This had an unusual aroma a bit like ethyl acetate.

We then got another product distilling at around 130 degrees.

See, we didn't get much of this, only a few, mls.

This had an unusual spicy petrochemical aroma.

And finally we got this 30 ml.

The third fraction which came over, between 190 and 200 degrees.

See, and was a yellow, color.

This had a sweet powerful aroma, a bit like, honey.

Here's the three fractions we collected.

We did a few, tests to see if we could make some guesses about, what we ended up with.

First, we tried measuring the rough melting point of the, fractions by chilling them down.

Here, still liquid at minus 10 degrees.

Fraction 3 melted between 0 and 10 degrees.

Focusing on fraction 3, we measured the weight of exactly, 10 mls which gave us the density.

We performed an iodoform test for alpha-methyl ketones by, adding iodine solution in ethanol, and then dilute sodium hydroxide, solution.

Fraction 3 is on the right, and on the, left is a control which is in the right.

This is acetone.

After gentle warming this was the result, a strong reaction, from the acetone, but some degree of yellow color above, and beyond that of the original product from fraction 3, as well.

Interestingly the pure fraction 3 did slightly decolorize iodine solution, when added to it directly, but not completely.

Our final test involved, adding iron 3 chloride solution to, fraction 3 which is here on the right, we used, salicylic acid on the left as a control.

This tests for the presence of any aromatic hydroxyl groups, or phenols.

The purple color is a positive, fraction 3 is not, phonolic.

This leaves us with a conundrum, we believe the fraction, 1 can change.

Fraction 2 contains some ethyl acetate as a result of a, slight impurity in our propionic acid, but other compounds is, well.

Fraction 2 could be a straight chain ketone as a, side product.

Fraction 3 contains some acetophenone, but is obviously a mixture, of different compounds.

We believe it contains some propiopinone but, without a lot more work we can't know for sure, or how much.

This synthesis route, seems attractive.

But in reality is going, to require a lot of work to extract any pure, product and with likely small yields.

But it was fun to find out.