Found by WizardX
HI from I2 + Ascorbic acid
Ascorbic Acid C6H8O6
MW= 176.12 grams/mole
MP: 190-192 *C
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
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C6H8O6 + I2 ==>> C6H6O6 + 2H(+) + 2I(-) E = +0.667 Volts
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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)
BP: 125.5-126.5 *C/760mmHg
D= 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 you can use azeotropic distillation for removal of the HI from the dehydroascorbic acid + HI solution.
At room temperature the reaction of HI with the hydroxy group 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.
Found by Rhodium
HNO3 in DCM
https://www.thevespiary.org/rhodium/Rhodium/chemistry/aromatic.nitration.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/aromatic.nitration.html)
Abstract
Pure dry HNO3 can be liberated from KNO3 with 96% H2SO4 directly into CH2Cl2 to yield solutions of variable concentration for use in a number of organic reactions. The present method efficiently replaces the employment of 100% HNO3 in some synthetic applications, avoiding the problems associated in storage and handling the acid.
Procedure
Unless otherwise specified, finely powdered KNO3 (50.0 mmol) was treated with the appropriate amount of 96% H2SO4 (47.5 mmol) and the mixture stirred for 15 min at room temperature; CH2Cl2 (25.0 mL) was added to the homogeneous slurry so obtained and the mixture cooled at 0°C with vigorous stirring. A solution of the substrate 1 (5.0 mmol) in CH2Cl2 (8.0 mL) was added dropwise and the stirring continued at room temperature for the required time. The reaction mixture was then poured into 10% aqueous Na2SO4 (30 mL) and the separated organic phase washed with 10% aqueous Na2SO4 (2×20 mL), dried over anhydrous Na2SO4, concentrated to dryness and the products obtained conveniently purified.
Notes on Safety:
The HNO3 in DCM is not stable and they reference possible explosions but state that they had no such problems. Be careful and only make this reagent when you need it, and dispose of extra.
Reference: Tetrahedron Letters, Vol 42(7), 1387-1389 (2001)