The reaction is moisture sensitive, so no water. Until now I have been using organic solvents like oleylamine and DMF, but the concentration saturates at 0.1mM.
Any insights that could push this limit into the range of 1-10mM is more than welcome.
Not knowing the nature of the reaction, it seems that glacial acetic acid may be a reasonable choice, as long as you take the adequate safety measures.
Thank you for your reply. I will try that. I hope the reaction's pH will not be an issue.
Hi Carlos, for the record, I tried glacial acetic acid, and solubility was almost nil. However, DMSO looks to be able to increase the critical concentration by at least a factor 15 under heat.
Dear Victor:
Sorry for being misleading. I actually did not look for data on solubility of PbCl2 in glacial acetic acid. My reasoning was as follows. Since lead acetate possesses some solubility in glacial acetic acid, I thought that by adding PbCl2 to glacial acetic acid, the Cl- ion could be expected to dissolve to some extent as HCl while the acetate ion should facilitate dissolution of Pb2+. So, both the ions might dissolve to some extent. Since HCl solubility in glacial acetic acid could be expected to decrease with temperature, while that of lead acetate should follow the opposite trend, better solubility might be expected at some mild temperature. Poor solubility of HCl seems to be the reason for this 'deceiving' solubility test. Anyway, solubility may possibly be enhanced by adding a convenient co-solvent. As dielectric constant of acetic acid is 6.2, one could think that substances of higher dielectric constant, such as pyridine (12.3-12.5); dimethyl sulfoxide, meaning DMSO (47.2--47.8); or formic acid (57.5--58.5), could possibly act as co-solvents.
Considering DMSO, one should remember that DMSO is a common ligand in coordination chemistry, so that it may dissolve PbCl2 by forming a complex involving both the Pb2+ and the Cl- ions. Therefore, it may leave these ions less readily available to participate at the intended reaction. The following reference may be useful, concerning solubility of PbCl2 in DMSO: G. W. Warren and H. Henein, “Solubility of PbCl2 in DMSO and DMSO—water solutions”, Hydrometallurgy, 46(1-2), 1997, 243-247.
Best Regards
Thank you Carlos for this answer, I am going to follow this direction and see what it gives.
The cosolvent is primarily intended as a modifier of the 'main' solvent properties. The ratio of cosolvent to solvent can be relatively small: possibly about 1:5 might be a reasonable figure.
Dmethyl sulfoxide (DMSO) seems promising as a possible cosolvent for use with glacial acetic acid. Possible complex compounds could be less stable than in DMSO alone, what may be favourable concerning the intended reaction. Also promising is pyridine, yet with similar problems to DMSO, being also prone to act as coordinating agent. Pyridine also dissolves PbCl2. Formic acid may perform worst than DMSO or pyridine, but complex compounds should not be a problem.
A related question can be seen at:
https://www.researchgate.net/post/Which_organic_solvents_can_be_used_to_disolve_PbI2_or_PbCl3_crystals
Sorry I didn't give a lot of feedback. Carlos' suggestion were good indeed. But in my case, we were trying to obtain something very precise of the reaction that apparently required the use of DMF, even if the maximum concentration was lower.
Thank you
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