Ascorbic Acid C6H8O6
Merck 11th Edition No. 855
Physical Properties
Molecular Weight 176.12 grams/mole
Mp 190-192 oC
pH = 3 (5mg/ml concentration)
pH = 2 (50mg/ml concentration)
Redox potential at first stage is pH 5.0 is E = +0.127 Volts.
One grams dissolves in 3 mls of water.
Possesses relatively strong reducing powers, decolourizes many dyes.
Aqueous solutions are rapidly oxidized by air. The reaction is accelerated by alkalies, iron and copper.
Making HI from I2 and Ascorbic Acid.
http://www.angelfire.com/scifi/WizardX/X4/ascorbic.bmp (http://www.angelfire.com/scifi/WizardX/X4/ascorbic.bmp)
C6H8O6 Ascorbic acid.
C6H6O6 Dehydroascorbic acid.
Balanced Reaction:
C6H8O6 ==>> C6H6O6 + 2H(+) + 2e E = +0.127 Volts
I2 + 2e ==>> 2I(-) E = +0.540 Volts
---------------------------------------------------------
C6H8O6 + I2 ==>> C6H6O6 + 2H(+) + 2I(-) E = +0.667 Volts
---------------------------------------------------------
The above reaction is used in analytical chemistry to determine quantitatively the amount of ascorbic acid.
In basic form: C6H8O6 + I2 ==>> C6H6O6 + 2HI
Simple Experiment.
Control Flask.
In a 50 ml flask, fill with 50 mls of demineralised water and add an iodine crystal. Stopper with rubber stopper.
Iodine solubility in water is 0.0013 moles in 1Lt at 25 oC
Reaction Test Flask.
In a 50 ml flask, fill with 50 mls of 1M Ascorbic Acid solution (176.12 grams in 1 Lt of demineralised water) and add an iodine crystal of equal size as the Control. Stopper with rubber stopper.
Observe that happens.
57% HI SOLUTION (HYDRIODIC ACID) : B.p 125.5-126.5 oC/760mmHg
Density 1.70 gr/ml ; 55-57% w/w HI is 0.936 to 0.99 grams of HI per ml.
If 57% w/w HI solution has a boiling point of 125.5-126.5 oC/760mmHg at which it form a azeotropic solution. Then lowering the pressure will lower the boiling point temperature and thus flash azeotropic distill the HI from the dehydroascorbic acid + HI solution.
At room temperature the reaction of HI with the hydroxy part of the glycol, -C(-OH)-C(-OH) functional group on the dehydrascorbic acid is very slow. Refluxing is required to iodinate or reduce to -CH2CH3
Therefore, by using flash azeotropic distillation (380-570mmHg) the reaction between the dehydrascorbic acid + HI can be minimized.
HI from I2 + Ascorbic acid is a method for making HI only. Then use reduced pressure azeotropic distillation (1/3 less of B.p 125.5-126.5 degC @ 760mm Hg) to purify your HI.
Approx. B.p 84 degC @ 506mm Hg
Do not think you can use the Ascorbic acid like RP, to recycle the I2.
Login Page.
http://www.angelfire.com/scifi/WizardX/login.html (http://www.angelfire.com/scifi/WizardX/login.html)
Plague: Have a read of this. Calculation of HI to Ephedrine Ratio
https://www.thevespiary.org/rhodium/Rhodium/chemistry/meth.hi-p.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/meth.hi-p.html)
We are looking basically at a two step "insitu" reduction reaction.