Sight down the C-2—C-3 bond, and draw Newman projection formulas for the
(c) Two most stable conformations of 2,3-dimethylbutane
So, here we've got 2,3-dimethyl butane and we're actually going to go ahead and convert it into bond line to convert into Newman projection at the most stable configurations. So, here we've got butane, so that tells me that we've got a four carbon chain and we've got 2,3-dimethyl, which means that we've got a methyl group on each carbon 2 and 3, so we've got 1 methyl here and 1 methyl here now let's say we're going to go ahead and look down this bond with our eyeball here, right? Beautiful. And we're going to give two Newman projections, okay? So we know that on the front carbon we've got 2 methyl groups and on the back carbon we've also got 2 methyl groups. So, what can we do here? well, we can say if we're going to give ourselves in the most stable conformations we're going to do something a little bit interesting, right? We consider we've got on the back carbon our 2 methyl groups here, okay? And then in order to give ourselves our front carbon as kind of stable, right? We're going to go ahead and put 1 methyl group here and 1 methyl group here, with our other hydrogen here, is there something more stable that we can, that we can get? absolutely, right? We can say, we can keep our back carbon the same and then we can say we've got our CH3 up here, our CH3 down here and our hydrogen here and in fact guys is it an easy way to see what's going on, right? It is just a look at our hydrogens, our hydrogens are next to each other over here and we've got four carbons 4 methyl groups kind of overlapping each other, right? this would be our gauche orientation and now over here we've got our hydrogens anti to each other, right? completely 180 degrees apart and then these are 180 degrees apart and these are 180 degrees apart, right? this would be our anti configuration, okay? So these are our two most stable configuration, especially our anti, okay? that's the best one we've got. Alright, so guys, let me know if you have any questions, if not, let's move on.