Hey Decan, how's the studying? I just took topscore 1 natural science test, & here's how I did:
Bio - 20
G. Chem - 17 (I was so pissed, careless mistakes, & wasn't focused)
Orgo - 21
TS - 20
Anyway, for your question, I just went over that problem yesterday too. What you must do is becareful of the temptation to jump straight to the answers. ALWAYS analyze your reactants before doing anything. I tend to make the mistake & jump straight to the answers, & that's probably why I get scores like 21 in orgo & 19 on the real thing, when I can be getting 29's, heh. I'm still working on this myself! The (CH3)3CO-K+ is a bulky base and won't be able to attack further within the butane molecule, so it will attack from the end. One thing my Kraplan teacher told me, is that whenever you have a bulky base, & you have a secondary or tertiary alkyl halide, you'll always get the Hoffmann elimination, aka the less substituted product. Had it been something like NaOCH3, a strong base, then you would get the Zaitstev or more substituted product. Hope this helps! Let me know if you need help with anything else.