Addition of Free Me₂Ge: to Alkenes and Alkynes on Glass Surfaces in the Presence of Water

Abstract

Traces of water on glass surfaces (even after heating) can decisively influence the course of a reaction. This is shown by the reactions of Me2Ge: with alkenes such as acrylonitrile and alkynes such as phenylacetylene in “anhydrous” medium. These reactions afforded poor yields of 1 and 2, respectively. On the other hand, reaction in the presence of water and silica gel gave 1 and 2 in nearly quantitative yield; the presence of water alone did not increase the yield. These findings indicate that acidic H atoms, formed on the silica surface, are essential for the reaction of the expected products with water.

Germylenes and stannylenes

“…This mechanism is supported by the use of D20 or H2180 instead of H20. 74,86 The detailed impact of the H20 molecules remains to be clarified (see also section C.4). Replacement of water by ROH or RCOOH gave the corresponding (alkoxygermyl)or (acyloxygermyl)propionitriles (see Scheme III).…”

“…Anyway, the product of the insertion into water or other acidic compounds like oximes74 is excluded as reagent, since its consecutive reaction, e.g., with acrylonitrile74 does not take place. 86 It seems, anyway, that the donor complexes will have more importance in future germylene chemistry than until now.…”

A Glimpse at the Chemistry of GeH2in Solution. Direct Detection of an Intramolecular Germylene–Alkene π-Complex

“…Intramolecular complexation with the CdC bond at the end of the side chain could explain the unusually low reactivity of the species toward isoprene and the alkene (DMP), as it should reduce the driving force for reaction with the CdC bond(s) of olefinic substrates but may have relatively small effects on the rates of other typical germylene reactions. The CdC bonds in germylenes 15 and (or) 16 may get involved along with the Ge(II) center in reactions with hydroxylic substrates, 61 which could explain why olefinic side products are formed in the reaction with AcOH but are not in that with MeOH (vide supra). If all this is correct, then it is the identities of these minor products that hold the key to the identification of the transient and the mechanism for its formation.…”