2i8 PRACTICAL ORGANIC CHEMISTRY Note that this is only a particular case of Williamson's general method for the preparation of ethers. (2) Purdie's Method, also chiefly for hydroxy-compounds. The substance is mixed with a small excess of dry silver oxide, and then shaken (or, if neces-sary, heated) with methyl iodide, a smooth methylation usually occurring. 2 ROH + Ag 4 O + 2 CH,I = 2ROCH, + 2AgI + H 1 O This method is used more particularly for hydroxy-compounds which also contain other groups (such as Cl atoms, etc.) which might be affected by the sodium hydroxide used in the following method. (3) Dimethyl Sulphate Method, for hydroxy-compounds and for primary and secondary amines, acid amides, etc. The substance is dissolved or sus-pended in water, a small excess (above the theoretical) of sodium hydroxide added and then the theoretical quantity of dimethyl sulphate, the mixture being finally shaken without external warming. Methylation is usually rapid, the dimethyl sulphate being converted to methyl hydrogen sulphate
This is the end of the preview. Sign up
access the rest of the document.