[carotis]

The Prof said, it is required to conduct reactions in protic solvents, liek water to make SN1 reactions occur. My question is, do those reactions if aprotic occur just very badly, or don't SN1 reactions occurs at all? What are the possibillities if lets say a primary carbon is the leaving group for a nucleophile, E1 maybe or none?

[Vidya]

leaving group on the primary carbon will give you primary carbocation which is itself is not good for SN1 or E1
Remember SN1/E1/SN2/E2 they all are always competing for reaction.Depending on the nature of the reactant,leaving group solvent and nucleophile it is decided which one is favored but it doesn't rule out all others completely.

[Dan]

The Prof said, it is required to conduct reactions in protic solvents, liek water to make SN1 reactions occur. My question is, do those reactions if aprotic occur just very badly, or don't SN1 reactions occurs at all?

S_N1 reactions can certainly occur in aprotic solvents, and some are routinely conducted in aprotic solvents. For example, introduction of trityl protecting groups with trityl chloride is certainly an S_N1 reaction and is typically performed in dichloromethane.

[kriggy]

Usualy more important is that reagents are all dissolved. Of course, one can run reaction in suspension but I had always better results even if it resolved in some weird(ish) mixture of solvents

[carotis]

I of course meant E2, was a tippo sorry