in lab we did experiment to study sn1 reaction of alkyl halides with AgNO3 in ethanol. we predicted that 1-bromobutane would not react by forming a precipitate because primary alkyl halides would not form a primary carbocation intermediate. However, it DID form precipitate. Mechanism-wise, how did AgBr form, other than though a primary carbocation intermediate.
Primary carbocation is formed in this reaction. It is because formation of AgBr occur very easy. But the reaction between R+ and Nu occur very fast after it as result the formation of product is observed.