CH CH3 CH3 CH R R R R REH3 53.8 288 17.3 CH2CH3 45 25 30 CH(CH3) 37.5 32.7 29.8 C(CH3)3 0 93 7CH3 CH3 R CH3 R CH3 R R + 0 93 7 37.5 32.7 29.8 45 25 30 53.8 28.8 17.3 C(CH3 ) 3 CH(CH3 ) 2 CH3 CH2CH3 R=