Protic organic solvent

The classical Michael reaction is carried out in a protic organic solvent—e.g. an alcohol—by use of an alkoxide as base—e.g. potassium r-butoxide or sodium ethoxide. 

This group tends to react violently with protic organic solvents, water, and the aprotic solvents, dimethylformamide and dimethyl sulfoxide. Their facile reaction with ethers is also potentially hazardous. 

The condensation of the silanols to siloxanes in non-protic organic solvents proceeds to completion. Lasocki has observed that the rate of silanol condensation is affected by small amounts of water added to the non-protic (dioxane) solvent [68]. The maximum effect is observed at approximately 0.75 M water. The impact of water on the rate may be due to solvation of ionic intermediates, its effect on the activity of the acids or bases, and its effect on the polarity of the solvent. 

The nucleophilic fluorinations have to be performed with the exclusion of water and under an inert atmosphere in a non-protic organic solvent. Since under those circumstances 1SF is insoluble, a phase transfer reagent has to be used. Often used are Kryptofix 2.2.2 and tetra-A-butylammmoniumhydrogencarbonate, the first one giving the better yields [11],... 

Tajima and co-workers have developed a novel environmentally friendly electrolytic system using solid-supported bases and protic organic solvents such as methanol [24], This method permits electrolysis without an intentionally added supporting electrolyte. Solid-supported bases are not oxidized at the electrode surface because electron transfer between two solids is, in principle, very difficult [25], Therefore, protons generated by the reaction of a solid-supported base and a protic solvent may serve as carriers of electronic charge. After the electrolysis, the solid-supported base can be easily separated by filtration and can be re-used. 

The glass electrode has found extensive use in non-aqueous solvents and seems to function quite well. ° On the other hand silver halide electrodes appear to be soluble in most aprotic solvents but behave reasonably well in protic organic solvents such as the alcohols. Butler has tabulated a fairly complete listing of solubility and stability constants for the various polynuclear silver halide species in many solvents. 

The presence of a less protic organic solvent may have a suppressive effect on reducing adsorption phenomena, and hence adsorption prewaves and waves, which in many cases unpredictably complicate the polarograms of organic compounds in real samples. 

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