Geminale Substituenteneffekte, 4. Abhängigkeit des inversen anomeren Effektes geminaler Nitril‐Gruppen von der Struktur

Geminal Substituent Effects, 4. — The Dependence of the Inverse Anomeric Effect of Geminal Cyano Groups on the Structure The heats of combustion and the heats of sublimation of malodinitrile (1a), ä‐alkyl‐ (1b,c) and å, å‐dialkylmalodinitriles (1 d ‐f) have been determined. From the obtained standard heats of formation group increments for CH2[CN]2], CH[(CN)2 Cl and C[CN)2C2] group are deduced. The comparison of their values with corresponding increments for monocyano alkanes reveals a synergetic destabilisation by two geminal cyano substituents of 11.5, 9.0 and 6.6 kcal/mol, respectively. Thus, this inverse anomeric effect decreases by increasing alkyl substitution.