The steps 5 to 10 work as described.
However the thermal rearangement in the last step has never worked for me as it was described there, the evil tar monster came around and polymerized to the extend that nothing decent could be recovered.
The most convenient method is rearanging the methylketmine in its HCl salt form in the following procedure:
Dissolve the methylketmine in 1.5 times its weight of ethyl benzoate heating to 50 Celcius was required to get everything in the solution.
After the contents have returned to RT gasseous HCl is bubbled in until a pH of <2 is reached, the solution is stirred well and heated as fast as possible to a temperature of 180 Celcius, this is maintained for 30 minutes and then cooled down to 0 Celcius for 1 hour, at this point the very dirty Ketamine HCl is filtered off.
The dirty Ketamine HCl was boiled in a royal amount of dH2O with activated charcoal (5% by weight) for 30 minutes and then the charcoal was filtered off, this was repeated once.
The final yellowish solution is freebased with 10% NaOH solution and the solvents are removed under vacuum, from there the freebase is recrystalized using pentane/ether
As for the preparation ethyl benzoate :
To 56 ml benzyl alcohol with stirring there was added 150 ml concentrated HCl,150 ml of water and 150 gram crushed ice, the precipated benzoic acid was filtered and recrystalized from boiling water. The yield was 44,9 gram
In a 500 ml RBF with 145 ml (115 gram, 2,5 mol) of absolute ethanol and 2,7 ml (5g) of concentrated sulphuric acid there was added 30 g (0,246 mol) benzoic acid and the mixture was gently refluxed for 6 hours. The excess ethanol was distilled off and the residue was cooled down, poured in a sep funnel charged with 250 ml water and 10 ml CCl4 the lower layer was kept and washed with sodium hydrogen carbonate until the evolution of co2 stopped. The ethyl benzoate solution is dried with 5 gram MgSO4 and filtered.
The ethyl benzoate solution is slowly distlled at first to remove the CCL4 fraction and then the fraction that comes over at 212-214 Celcius is kept. The yield was around 30 gram
