Kneading ball milling

Keywords kneading ball milling, quantitative, condensation reaction, aldehydes, hydroxylamine, hydroxylamine, oximes... 

Hydroxylamine hydrochloride (5.00 mmol) and the aldehyde or ketone 1 (5.00 mmol) were kneading ball-milled in a double-walled 10-mL stainless steel vessel with two balls of 12 mm diameter at 20-25 Hz for 10 min at 45-50 °C (a-e) or for 30 min at 65-70 °C (f-h). A quantitative yield of the oxime hydrochloride hydrate 2 was obtained. The salt 2 already carries the catalyst for most of the various synthetic uses of the oximes. Washing with aqueous NaHC03, if required, can liberate the free oximes 3. 

The crude product is converted to a finished pigment by means of various comminution techniques. These include ball milling in the presence or absence of a solvent, attrition by kneading, acid swelling, or add pasting. The apphcation properties of the finished product and its ultimate shade (a function of partide size and shape as well as size distribution) are determined to a large extent by the technique seled-ed. 

The second paper (10CEJ4347) [cited in (11CGD4731)] concerns the related case of 2-thiobarbituric acid (34). Using kneading, all mechanical conversions were carried out in a ball mill Retsch AS200 basic of volume of lOmL.The quantity of the sample miUed was about 300 mg. The 11 tautomers are represented in Figure 8. 

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