02-10-04 11:46
No 487728
When using pseudo-freebase instead of Hcl in a reation does one use the same ratios of the other pre-cursers? Does the reaction procede in the same way? Is there anything differant that needs to be done?
(Chief Bee)
02-10-04 14:20
No 487743
It depends on which reaction.
The Hive - Clandestine Chemists Without Borders
(goat)
02-10-04 17:15
No 487780
among other things.
one would think it to react more vigourously when it says "HI" to "HI". avoiding the rumoured nasty heat-related by-products might require a much more gradual introduction to heat, than with the salt. swim has heard rumours of fb rxns staining the ceiling. more water?
(Newbee)
02-11-04 05:10
No 487877
In reference to the Rp/ I2 reaction
(Of Counsel)
02-11-04 10:06
No 487907
The freebase form of pseudo weighs approximately 82 percent of the weight of the HCl form. Multiply the mass of the freebase pseudo you wish to react by 1.22 to get the equivalent mass of pseudo HCl, and use the other precursors in proper ratios to the mass you would have if the pseudo were the salt form. Note that the ratios given for the phos acid synth in the "red phosphorous substitute" thread are for the freebase form of the molecule.
Bear in mind that when you put the freebase pseudo in an acid, it will take a molecule of the acid and become a salt form. This reaction is frequently exothermic, and the conversion of freebase pseudo to freebase HI is exothermic. If you are making HI in situ and doing a freebase reaction, you will have two exothermic reactions taking place at the same time-- the one with the I2 and red P making HI, and the one with the HI and freebase pseudo making pseudo HI.
I believe this double reaction is the source of the failed reactions that were mentioned in early freebase pseudo threads. Both Jacked and VideoEditor commented on the need to manage the start of the reaction to avoid it becoming too exothermic and damaging some of the pseudo, resulting in poor yields.
My experiences with freebase pseudo followed VideoEditor's lead for the most part, and I used the water he recommended be used. I can't recall "losing" a freebase reaction to heat, nor do I recall doing one with less water than VideoEditor recommended using. Since that amount of water is in line with the water I added for long wet refluxes, and since I was content to reflux freebase as well as the salt forms of pseudo, I never had a problem with overheating at the start of the reaction.
You might consider making your HI then adding the freebase pseudo as an alternative to a wet start, if so inclined. you could also limit the speed of the exothermic reactions if you do not use an excess of red phosphorous, and/or add the iodine in portions at the start of the reaction. This precaution will slow the generation of HI, and by the same token slow the conversion of the freebase pseudo to the salt form. I have used both alternatives, but since I am an advocate of the long wet reflux, have had no problem with the exothermic reactions since I have enough water in the flask to buffer them enough to prevent damage to the pseudo.
If you want to do a drier cook, you will have to carefully baby the pseudo through the HI production phase, using an ice bath to limit the heat and slow the HI production to keep the reactions from proceeding too hot and too fast. Jacked has posts describing an effective way of doing this.
mostly harmless