▁will ▁give ▁a ▁product ▁derived ▁from ▁the ▁more ▁stable ▁car b ocation ▁rather ▁than ▁the ▁simple ▁substitution ▁product . ▁ ▁Sol vent ▁effects ▁ ▁Since ▁the ▁SN 1 ▁reaction ▁involves ▁formation ▁of ▁an ▁un stable ▁car b ocation ▁intermediate ▁in ▁the ▁rate - det erm ining ▁step , ▁anything ▁that ▁can ▁facil itate ▁this ▁will ▁speed ▁up ▁the ▁reaction . ▁The ▁normal ▁sol vent s ▁of ▁choice ▁are ▁both ▁polar ▁( to ▁stabil ize ▁ion ic ▁inter medi ates ▁in ▁general ) ▁and ▁prot ic ▁sol vent s ▁( to ▁sol v ate ▁the ▁leaving ▁group ▁in ▁particular ). ▁Typ ical ▁polar ▁prot ic ▁sol vent s ▁include ▁water ▁and ▁alco h ols , ▁which ▁will ▁also ▁act ▁as ▁nucle oph iles ▁and ▁the ▁process ▁is ▁known ▁as ▁sol vol ysis . ▁ ▁The ▁Y ▁scale ▁correl ates ▁sol vol ysis ▁reaction ▁rates ▁of ▁any ▁sol vent ▁( k ) ▁with ▁that ▁of ▁a ▁standard ▁sol vent ▁( 8 0 % ▁v / v ▁eth an ol / water ) ▁( k 0 ) ▁through ▁ ▁with ▁m ▁a ▁react ant ▁constant ▁( m ▁= ▁ 1 ▁for ▁t ert - but yl ▁ch lor ide ) ▁and ▁Y ▁a ▁sol vent ▁parameter . ▁For ▁example , ▁ 1 0 0 % ▁eth an ol ▁gives ▁Y ▁= ▁− 2 . 3 , ▁ 5 0 % ▁eth an ol ▁in ▁water ▁Y ▁= ▁+ 1 . 6 5 ▁and ▁ 1 5 % ▁concentration ▁Y ▁= ▁+ 3 . 2 . ▁