Optical activity Q and more (ochem)

[NuckingFutz]

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I have no idea how to determine whether or not a product is optically active or not. Does it have to do with it being chiral?? How does it being optically active make a difference in a reaction?

Is there any question the DAT could ask other than "which of the following is optically active?"

Thanks 😀

ALSO, is there a method to determine whether or not a product will undergo syn or anti addition? I'm never good with questions that shows the same answer differing in stereochemistry. All I know is that SN2 reactions attack from behind, thus inverting the product. Any advice is appreciated 🙂

 

[Aceofspades]

I have no idea how to determine whether or not a product is optically active or not. Does it have to do with it being chiral?? How does it being optically active make a difference in a reaction?

Is there any question the DAT could ask other than "which of the following is optically active?"

Thanks 😀

ALSO, is there a method to determine whether or not a product will undergo syn or anti addition? I'm never good with questions that shows the same answer differing in stereochemistry. All I know is that SN2 reactions attack from behind, thus inverting the product. Any advice is appreciated 🙂

1. A compound is optically active if it is chiral, but not meso/symmetrical. Also note that allenes are chiral.

2. As for the syn/anti addition... different reactions produce different products. Either know the mechanism for each reaction covered in the DAT (hard way), or just memorize the reaction and sterochemistry of the products (easy way). Either should work fine.

 

[klutzy1987]

1. A compound is optically active if it is chiral, but not meso/symmetrical. Also note that allenes are chiral.

2. As for the syn/anti addition... different reactions produce different products. Either know the mechanism for each reaction covered in the DAT (hard way), or just memorize the reaction and sterochemistry of the products (easy way). Either should work fine.

1) Allenes are only optically active if they have different substituents on the carbons. Also an individual compound can be optically active but when in solution or something it wmay form a racemic mixture and then will be optically inactive.

 

[AdaAda87]

Do we have to know how to calculate the optical activity like the angle that it is optically active for the DATs?

 

[klutzy1987]

Do we have to know how to calculate the optical activity like the angle that it is optically active for the DATs?

I dont even nkow what you are talking about. So hells no you dont need to know.

 

[Aceofspades]

Do we have to know how to calculate the optical activity like the angle that it is optically active for the DATs?

You cannot calculate the optical activity without physically going in a lab and busting out the spectrophotometer. For the DAT you will NEVER know the optical rotation magnitude or direction. It's impossible to predict, calculate, or measure without doing the actual experiment.

 

[AdaAda87]

Thanks guys! I was talking about specific activity! you guys saved me from memorizing an eq!