Sp2 optically active destroyer 59

[RT0223]

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I'm still confuse why Sp2 can be optically active after reading the ans key. I thought it only apply to Sp3. Can someone please elaborate a little more?

 

[RT0223]

come on, need help over here!

 

[Tina324]

yes! that q was buggin the heck outta me. i wanna know why too =)

 

[Holopeachy1]

Im not sure what you guys are confused on, but if you look at the examples you have to look at the chiral carbon. Now all of the examples have either chiral carbons, sp3 or an achiral sp3. In order to be optically active you need to have a carbons that is attached to 4 different atoms.

Does that make sense, im horrible at explaining 😛

Although one carbon is sp2 there is atleast one that is sp3, for purposes of chirality you only look at the carbon that is sp3.

 

[RT0223]

Im not sure what you guys are confused on, but if you look at the examples you have to look at the chiral carbon. Now all of the examples have either chiral carbons, sp3 or an achiral sp3. In order to be optically active you need to have a carbons that is attached to 4 different atoms.

Does that make sense, im horrible at explaining 😛

Although one carbon is sp2 there is atleast one that is sp3, for purposes of chirality you only look at the carbon that is sp3.

but a) only has 3 things attached to the Sp2 carbon (1H, 1 CH3, and 1 C)?

the ans key said something like... 2 pi bonds are mutually perpendicular and the central C is part of both, 2 pi systems don't overlap. Can someone please translate it to English?

 

[Holopeachy1]

Ok I take it back, i see why you are confused, because of the allene. That stupid allene, I sort of just memorized the fact that allenes could be chiral when there are bonded to different substituents that lie in different planes. because it doesnt allow it to have a plane of symmetry!

I know thats not a good explanation but I tried...sorry!

 

[tranv117]

the definition of chirality is that the object's mirror image cannot be superimposed upon itself, which is true of the allene shown in destroyer. Notice the counter example in #52 has two Hs. That molecule would be superimposable on its mirror image which is why its achiral.

As for optical activity, I always thought it had to be determined experimentally with the exceptions of a racemic mixture or meso compounds.