Other solvent based cleaning systems

Besides the already mentioned solvent based cleaners, there are some special solvents on the market. However, due to their physical and toxicological character, most of them are used for special applications. The advantages and disadvantages of the different products are summarized below. 

Due to their extremely low surface tensions combined with excellent wetting character, siloxanes were recommended for electronic cleaning applications. While siloxanes can be 

Chlorinated solvents such as trichloroethylene or 1.1.1-trichloroethane are nonflammable and excellent cleaning results can be achieved on especially non-polar residues. However, ionic contamination cannot be removed sufficiently. 

There are predominant environmental issues, in particular, their ozone depletion potential, which makes their use in electronic cleaning applications obsolete. 

Cleaning fluids based on formulations using n-propylbromide (nPB) have to be regarded very critically. Since these products also contain halogens, they cannot be considered to be real alternatives for chlorinated or fluorinated hydrocarbon mixtures. Due to these open environmental questions, cleaning applications using n-propylbromide formulations are still not very common, especially in Europe. 

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Before 1960, only sodamide and potassium amide were used for the a-metallation of nitriles ( CH—C=N) and successful couplings with electrophiles were restricted to alkylations [la]. The extension of the number of base-solvent systems allowed a clean a-metallation of a variety of nitriles and the subsequent successful reaction with other nucleophiles [lb]. The use of a-metallated dialkyl-aminonitriles R2NCH(R )C=N and protected cyanohydrins R CH(C=N)OR (R = SiMe3 or CH(CH3)OEt) as acyl-anion equivalents in organic synthesis has been reviewed by Albright [2]. 

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