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|2C-HxHCl chlorination with elemental chlorine|
In PiHKAL, Shulgin describes chlorination of 2C-H in the form of acetate salt in glacial AcOH with elemental chlorine with the over-modest 22% yield. It turned out that protection of the amine function of 2,5-DMPEA/2,5-DMA with some anion of a strong acid in different halogenation reactions improves the yield greatly: doubling in the case of iodination with AgNo3/I2 and chlorination with elemental chlorine. Yields in bromination of hydrochlorides of the abovementioned amines are also higher, than in classical method with the acetate salt. The only disadvantage is that more solvent is needed.
Post 521733 (Erny: "Хлорирование 2C-HxHCl элементарным хлором", Russian HyperLab)
24 ml of glacial acetic acid containing 1,14 g elemental chlorine were added to the solution of 3,5 g 2C-H hydrochloride in 60 ml AcOH in a beaker, wrapped in aluminum foil. Evolution of HCl gas began immediately and was very intense. Reaction proceeded for 10 min at room temp. and was poured into ~ 150 ml cold sodium thiosulphate water solution. SWIM's idea was that thiosulphate would not react with AcOH, but it did, though not to a great extent with the evolution of SO2 and the deposition of sulphur. Cold NaOH solution would have been a better choice.
The whole thing was then made basic with NaOH. Extraction with benzene (~ 100 ml) led to the formation of emulsion; addition of enough NaCl and putting the solution in the freezer for 40 min helped to separate the layers. Benzene layer (yellow colored) was separated and extracted with aq. HCl until pH was slightly higher than 7 (keeping the pH little above neutral doesn't let the colored impurities to pass into water phase).
Water solution of amine hydrochloride was evaporated, the residue dried, grinded with acetone, and washed with acetone on a Buechener.
Yield: 1,6 g of 2C-C hydrochloride (39,3%).
One hyperlab bee stated that chlorination of 2C-H chloride instead of acetate may give up to 90% of a pure product, inducing SWIM's interest in this reaction. This is still to be confirmed, maybe by some more accurate bee.
|Chlorination with Cl2|
There is a German text that states not only the monochlorinated, but also di- and trichlorinated product is present.
But I don't know... Why would it happen for Cl2 and not for Br2 and I2?
-+- Александр Бородин -+-
One reason might be steric hindrance, while I believe there's others. Chlorine is small compared to bromine, iodine is the biggest of the (non-radioactive) halogens. There's fair chances of a thin guy sitting next to another thin one (disubstituted product). A fat guy taking a seat right next to another heavy-weighter is unlikely. It might, but you have to wait long, or take drastic measures to make it happen. In the 2C-H bromination the rxn is long over before any two fat bromine fellas have descided to sit next to another...