Which Materials Have Optical Activity?

[omni]

Which of the following materials have activity Optical ?

i know it must have an Chiral molecule,but still i am not know in this list who have it.

thanks for help.

 

[Borek]

What is a definition of chiral molecule? Can you try to apply definition to these molecules?

 

[omni]

well A chiral molecule is a type of molecule that lacks an internal plane of symmetry and has a non-superposable mirror image. The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom.

i know that activity Optical is possible only in chiral molecules.

can you show me one molecule from my list then i can try to deduce from it.

thank you.

 

[Borek]

Chiral molecules have (at least) one assymetric carbon. That means carbon with four different substituents. Take a look at your molecules, count different groups attached to each carbon - if there is four, you have a chiral molecule.

http://en.wikipedia.org/wiki/Chirality_(chemistry)

 

[omni]

ok i think i start to understand,
so if i correct the Chiral molecules in my list is A,C,E in my picture here is hard to see but the carbon atom in molecules c have an covalent bond with hydrogen in the left side.
the rule "Chiral molecules have (at least) one assymetric carbon. That means carbon with four different substituents" is also acceptable when there an double covalent bond like we have here when the carbon atoms have an double covalent bond with hydrogen atoms?
thank you.

 

[Borek]

How many substituents in the carbon with a double bond?

 

[omni]

well there 1 substituents in the carbon with a double bond Because the double bond are connection with 1 atoms.

look in the new picture i mark in blue the different substituents Including the atom O that i think he have double bond with the assymetric carbon.

as you can see E and A is almost the same.

thank you.

 

[omni]

"a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon"

 

[Borek]

OK, I will put it differently. You have a carbon with a double bond. Is it possible that it has four substituents? Take a look at the picture you have just attached - to how many atoms/groups of atoms is the carbon bonded? Four?

 

[omni]

no only to Three atoms/groups of atoms (CH,O,OH)

really thank you.

 

[omni]

hi. i found that molecules A,C,E are activity Optical that is correct ?
thanks.

 

[Borek]

You are correct so far, but it is not a full answer.

Chiral substance may have more than one chiral carbon.

 

[omni]

D have than one chiral carbon yes?

thanks