How can a methyl group act as an electron releasing group without containing any lone pair of electrons?

A carbon atom bonded to other hydrogen is slightly electron rich because carbon is somewhat more electronegative than hydrogen, and so that extra electron density can be transferred to neighboring atoms through bonding interactions (through sigma bonds).

From the USM.Maine.edu page (link to the left of this answer):

"In the case of a C-H bond, the electron density is higher in the vicinity of the carbon than the hydrogen because carbon is more electronegative than hydrogen. Relative to H, the inductive effect of C is electron withdrawing. To a first approximation a C-C bond is non-polar because there is no difference in electronegativity between the two carbons. The polarities of the C-N, C-O, and C-F bonds are all such that the electron density is lower around carbon. Relative to carbon, the inductive effects of N, O, and F are all electron withdrawing. Finally, in the C-Si bond, the electron density is higher around carbon than it is around silicon. Relative to Si, the inductive effect of C is electron withdrawing. Conversely, the inductive effect of Si is electron donating relative to C."

First answer by JEK. Last edit by JEK. Contributor trust: 1679 [recommend contributor]. Question popularity: 26 [recommend question]