Acrolein diethylacetal

A dicarbocyanine dye, dithiazinine (79), is used as a broad-spectrum anthelmentic agent, although, interestingly, it seems to have been prepared initially for use in photographic emulsions. It is made by heating 2-methylbenzothiazole ethiodide (77) with the malondialdehyde equivalent, B(ethylmercapto)-acrolein diethylacetal (78) in the presence of pyridine. There apparently ensues a sequence of addition-elimination reactions quenching the reaction mixture with potassium iodide solution results in separation of green crystals of dithiazanine iodide (79). ... 

Scheme 21.1 Heck arylation of acrolein and acrolein diethylacetal. was the most important parameter among all those evaluated (i.e. KCl, solvent...) that affect the selectivity (Scheme 21.1, Route 3). However, moderate activity and selectivity were achieved when using the 9-bromoanthracene whatever the olefin (8). This was attributed to the large steric hindrance of this substrate.

The last step of this sequence is a transacetalization with acrolein diethylacetal to give acetal 17. 

Considering only one example, an equimolar mixture of 22D and MA converts to a 100% yield of copolymer when heated in toluene for 2-3 h at 55-60°C, with 1.0 wt. % AIBN initiator. In the preparation, the solid polymer precipitates rapidly from the toluene after only a few minutes reaction time. Linear and cyclic acetals with vinyl unsaturation are easily prepared from acrolein and alcohols or glycols. Monomers such as acrolein diethylacetal... 

Acrolein diethylacetal 24 and MA were copolymerized in benzene with free-radical initiation to obtain a remarkably uniform composition (1 1), regardless of the monomer feed ratios/ It was suggested that the CTC brought about the alternating copolymerization. 

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