Influence planetary tables

Addition of amines to acetylene carboxylates 246 in ball mill was studied by Stolle and Thorwirth (Scheme 3.65) [44]. Employing solvent-free protocol in planetary ball mill in conjunction with quartz sand as inert grinding auxiliary, a number of enamines 247 were prepared in high yield (Table 3.33). No further catalysts or additives was required to accomplish reaction within 5 min. Obtained E/Z ratios vary with amine applied in the case of dicarboxylates, mainly the E-isomers have been identified. In contrast, reactions with propiolates and anilines yielded favorably the Z-isomer, whereas secondary alkyl amines furnished the E-isomer preferably. Simple stirring of DMAD and aniline in flask afforded only 80% conversion and chemoselectivity was lower (E/Zratio of 87 13) in comparison to ball milling. A common method for synthesis is the reaction in solvent, for which was found to have a strong influence on the E/Z ratio of the product, while this influence is not present in solvent-free milling. 

Because of their interest in interstellar chemistry and for planetary atmospheres, many carbon-based species are present in the table either as radicals or stable reagents. The most intensively studied radicals are C2H, CH and C4H whereas acetylene and ethylene are the most investigated reagents. For this reason it is interesting to gather several data from different publications and show how the reactivity of stable molecules is influenced by the nature of the radical. This is presented in Fig. 2.7 for... 

FIGURE 2.11 Major surface currents in the oceans. Surface currents are mainly wind-driven, but are also influenced by the oceans boundaries and by the Coriolis force. Not illustrated here are deep-water currents, mainly driven by differences in water density. For example, water carried northward by the Gulf Stream sinks after giving up much of its heat, and flows southward in the Atlantic Ocean as a near-bottom current. On the planetary scale, one net effect of ocean currents is to transport large amounts of heat from warm equatorial regions toward the poles (Earth Science Reference Tables, 2011). 

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