I will use propanol and sodium hydroxide in the experiments. I tried tests, but did not. Can you give me information about the rates?
May 24, 2017, 06:03 PM
I made biodiesel using 99%+ anhydrous 2-propanol also named isopropanol. A problem is that the triester with glycerol backbone bonded to three fatty acid molecules will not react in the regular transesterification where base (caustic, sodium hydroxide, potassium hydroxide) + alcohol + heat + vegetable oil to yield the isopropyl biodiesel, but the normal reaction does not work, probably due to steric hinderance where the alcohol functional group is closely surrounded by two methyl groups adjacent to the carbon bonded to the oxygen atom and hydrogen atom. I made the 2-propanol , isopropyl biodiesel using anhydrous (dry, without water) isopropanol plus a catalytic amount (small amount) of 98% concentrated sulfuric acid plus the free fatty acid plus heat to yield isopropyl biodiesel. The difference in making isopropyl biodiesel is different properties like viscosity , vapor pressure, freezing point et cetera. Purifying the product biodiesel using magnesium silicate probably is a good method of removing impurities after doing the Fischer Esterification where alcohol plus a weak organic carboxylic acid (like vinegar , acetic acid) plus a small amount of a strong mineral type inorganic acid (sulfuric acid) yields the ester (biodiesel) plus water that is produced in the reaction plus residual strong acid in the liquid material . It is necessary to use isopropyl alcohol with very little water in it, for the Fischer Esterification to work. I think it's Utah Biodiesel that can supply 99%+ anhydrous (without water) isoproply alcohol at a reasonable price for research chemistry studies in synthetic fuels (biodiesel).This message has been edited. Last edited by: WesleyB,
May 24, 2017, 07:32 PM
"The classic synthesis is the Fischer esterification, which involves treating a carboxylic acid with an alcohol in the presence of a dehydrating agent:
RCO2H + R′OH ⇌ RCO2R′ + H2O " - wikipedia
Good to hear you are still at it.
May 25, 2017, 12:14 AM
I did a mathematics calculation. The quantitative amount of isopropanol required to react 100% with stearic acid (18 carbon atom chain), the most common fatty acid, is for 1000 grams of free fatty acid requires about 268.6857505 milliliters of anhydrous isopropanol at 20 degrees centigrade. But for the Fisher Esterification an excess of alcohol, the less expensive chemical , needs to be used in the reaction to get a more compleat reaction. I said twenty degrees centigrade because at different temperatures the volume changes a bit for the alcohol.
May 25, 2017, 02:38 AM
How do you work out the amount of sulphuric?
May 25, 2017, 11:13 AM
A catalytic quantity means any amount will work. 5 milliliters of concentrated sulfuric acid would be fine for 1 kilogram of free fatty acid plus the anhydrous alcohol. A small problem is concentrated sulfuric acid reacts with the double bonds in fatty acids, but the brown product can be removed using magnesium silicate.
May 25, 2017, 04:49 PM
The article on fischer esterification refers to sequestering the produced water to push the reaction over to the right hand side, so there would need to be enough to keep things "dry", no?
May 26, 2017, 09:08 AM
Water is a product of the Fischer Esterification. Adding water pushes the reaction to the left, starting materials are on the left side of the reaction equation. Ideally removing the water product as it's produced would be best. The fatty acid plus anhydrous alcohol (without water) plus concentrated sulfuric acid yields the ester plus water. Note there is no water in the starting materials. The dryer the better to cause the reaction to go farthest to the right (right side of the reaction equation is the products side).
September 28, 2017, 08:46 AM
Fascinating approach. Why use the IPA over MeOH? It's a terrifically versatile chemical, but in Australia not available in industrial quantities (like MeOH).
November 16, 2017, 02:10 PM
Biodiesel made using isopropyl alcohol or 1-propyl alcohol has different properties. Freezing temperature, flow, viscosity, boiling point, vapor pressure, and other differences.