Grignard reagents Color Test

Grignard and lithium reagents the copper intermediates do not react with Michler s ketone 40, 60, 69, 119) [Gilman Color Test I (123)]. 

Gilman s test for the presence of Grignard reagent is useful about 0.5 ml. of the ethereal solution is removed with a capillary dropping tube and treated with an equal volume of a 1% solution of Michler s ketone in dry benzene and then, slowly, with 1 ml. of water. Addition of several drops of a 0.2% solution of iodine in acetic acid then produces a characteristic greenish blue color if Grignard reagent was present. 

Dimethylcadmium A solution of methylmagnesium bromide (0.3 mole) is prepared as usual from methyl bromide and magnesium. It is then cooled in ice and treated slowly with finely powdered, anhydrous cadmium chloride (0.16 mole). The ice-bath is then removed and the mixture is stirred for 0.5 h. Finally the color test (page 879) is applied to make sure that the Grignard reagent has been wholly consumed. 

The Gilman test (38), a color test for the detection of a Grignard reagent, is performed on each preparation prior to its use in the synthesis of C-palmitic acid. First, 0.5 mL of the Grignard solution is treated at room temperature with an equal volume of a 1% solution of 4,4 -bis(di-methylamino)benzophenone (Michlers ketone) while shaking. The... 

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