barnabe

further looking for DCm and pyridine, i found that, which is quite interesting i think: http://www.chemistryviews.org/details/ezine/737151/Puzzling_Pyridine_Problem_Probed.html pyrdine derivatives/salts can form unanticipated or undesired compound(s) with DCM. However the formation of them seem slow.

Sorry if was not clear: I meant the evaporation of DCM in aqueous emulsion. Say i have a ratio of 1 to 4 or 5 DCM to water, emulsified and sonicated with the compound and a protein. I wonder if all DCM contained in droplets can easily escape or can resist evaporation due to droplet entrapment.. I understand one can t say about bonding phenomena without knowing the organic compound or the protein.. But i mean simply the droplet state of DCM and its influence on evaporation.. thanks

great stuffs. Thanks for the support. Last question if i may, a bit unrelated. To your knowledge, do emulsive droplets of a solvent (like DCM) render the evaporation of that solvent harder/longer? do the trapped micro droplets of a solvent affect its evaporation? regards

Hi hypervalent_iodine, thanks a lot for your response. You seem to implicitly approbate the deductions i made above (?) regarding the suitability/"substitutability" based on the specs/protocol I gave. ( i understand one can only gives a position based on those parameters) That would be great in effect to replace with DCM wich i already use and is in effect really practical. If i can use same amount of DCM as ether, i understand from that that their difference in water solubility is not an important parameter for the formation of the pyridinium hydrochlorate: the latter will form from aqueous HCL in emulsive way (shaking) rather than solution way...(?) thanks

Hi Again, i got this idea, please tell me your opinion. It is simply the use of Dichloromethane as replacement of ether Pyridine Hydrochloride is insoluble in DCM just like ether. The washing with water might be even easier than with ether as solubility of DCM in water is lower than that of ether. Also, my compound is soluble to good ratio in DCM. It remains to see (calculate) if HCL can dissolve in enough quantity for the molar ratio of pyridine in the intial DCM. DCM would be ideal in terms of evaporation/flammability Thanks for your opinion. as to the pending question of aqueous HCL in DCM in the protocol i have with ether it s like this: the pyridine salt (formed with the organic compund) 0.8 g is dissolved in ether 50 mL and shaken with aqeuous HCl (1N, 50 mL) 1 h So, I m not sure as to the quantity needed if ether replaced by DCM. Since water is like more than 3 times less soluble in DCM than ether, maybe i should use 3 times more DCM in the above procedure..?

sorry but i m not sure i get what you mean. The aqueous phase washes the pyridine hydrochloride. Plus the compound is totally insoluble in the aqueous phase. But i ll test the solubility of the compunds in ethyl acetate. regards

thanks. i have found NO data about solubility in ethyl acetate, but i have plenty so i can try incrementally to dissolve the compound in it to figure that out and check until some solid crytals are floating. Tha twould be a simple way to go right? thx

Hi, thanks hypervalent_iodine for your insights. I do have a rotavap with vacuum. Just not the fume hood. I have to check if the compound can withstand such heat. would you have any othe solvent with lower boiling point and making it easy to wash the HCL layer with water? regards

Thanks for the 2 last answers. That step i described is litterature. I have not performed it yet. So i can not be more explanatory without extrapolating. Those are the exact terms. It is not specified if the washing is done with separatory funnel or not. I asssume The HCL-Pyridine is washed with water in aqueous form from the ether solution. After checking, Fume hood will be a bit complicated in terms of time/logistics to get. So i m still interested in alternatives to ether. I ll check with the solvents proposed. The objective is again to remove newly formed pyridine HCL salt (solid or not) from the solutionto get only the compound in the solvent. Regards @hypervalent_iodine regarding inhalation: i m using active coal masks. IS it protective enough? It seems i have to find a solvent in which pyridine salt is soluble, pyridine hydrochloric is insoluble, like ether, and in wich aqueous HCL is soluble to some extent (comparable to ether), like ether again. Those 3 properties. and washable with water

hi, i am isolating an organic molecule from a fruit. It is itself a trivial, non hazardous coumpound. i ll see if i can add the hood. But Would you think of a possible alternative to ether in those setting and properties (slightly acidic coumpound, insoluble in water, but soluble in toluene and DCM)? at least less flammable and volatile? thanks

Hi, thanks for your responses. To clarify the process: The pyridine salt is dissolved in ether and shaken with aqeuous HCl. The ether solution is then washed with water , dried and evaporated to give the compound. As said, i d rather use another solvent than ether (no fume hood in my settings). Any idea? Thanks

Hi, I make a pyridine salt which contains the pyridine and an organic weak acid. The standard procedure to isolate the acid and remove the pyridine is to dissolve the salt in Diethyl ether with HCL, and let the diethy ether evaporate, which leaves the organic acid crystals with purity 99%. But i would like to use something else, less flammable than ether to isolate the said acid. Do you have any idea what could be used? The acid is composed of C H O and is completely insolube in water. It is mildy soluble in alcohols and quite soluble in dichloromethane. Thanks for any motivated suggestion. Regards