Using the Cahn-Ingold-Prelog sequence rules,assign priorities to the groups around the chiral carbon in carvone. Draw the structural formulas for (+)- & (-)-carvone with the molecules oriented in the correct position to show the R & S configurations.
We can't draw structures on this board.
They are drawn on the wikipedia page
http://en.wikipedia.org/wiki/Carvone
I would be tempted to redraw them using a Fisher projection http://en.wikipedia.org/wiki/Fischer_projection
to demonstrate you understand the application of the C-I-P rules.
To assign priorities to the groups around the chiral carbon in carvone using the Cahn-Ingold-Prelog (CIP) sequence rules, you need to follow these steps:
Step 1: Identify the chiral carbon in the molecule. In carvone, the chiral carbon is the one with the asterisk (*) attached to it.
Step 2: Assign a priority number to each substituent group based on the atomic number of the atoms directly bonded to the chiral carbon. The higher the atomic number, the higher the priority. If two groups have the same atom directly bonded to the chiral carbon, move to the next atom until a point of difference is found.
Step 3: If the molecular formula is identical, compare the substituents atom by atom moving outward from the chiral carbon until a difference is found.
Step 4: When assigning priorities, if a group is oriented away from you (into the page), mentally draw a line connecting the chiral carbon to that group. If the order of the groups cannot be determined, rotate the molecule until a decision can be made.
Now, let's assign priorities to the groups in carvone:
1. Assign priority numbers to the groups based on their atomic numbers.
- The group with the highest atomic number directly bonded to the chiral carbon gets priority 1.
- The group with the second-highest atomic number gets priority 2.
- The group with the third-highest atomic number gets priority 3.
- The lowest priority group gets priority 4.
In carvone, the chiral carbon has four substituents: a hydrogen (H), a methyl group (CH3), a cyclohexene ring, and a ketone (C=O) group. Let's assign priorities based on their atomic numbers:
- The cyclohexene ring contains only carbon and hydrogen atoms, so compare the next atom outward.
- The methyl group has a higher atomic number than hydrogen, so it gets priority 1.
- The ketone group contains carbon and oxygen, and since oxygen has a higher atomic number than carbon, it gets priority 2.
- Hydrogen is the lowest priority and gets priority 4, leaving the cyclohexene ring with priority 3.
Now, let's draw the structural formulas for (+)- and (-)-carvone:
- (+)-Carvone has an R configuration, meaning the highest priority group (1) is on the right side (clockwise) when looking at the chiral carbon. The structural formula would be as follows:
CH3 CH3
| (+) |
H — C* — CH — CH2 — C=O
| |
CH2 CH3
- (-)-Carvone has an S configuration, meaning the highest priority group (1) is on the left side (counterclockwise) when looking at the chiral carbon. The structural formula would be as follows:
CH3 CH3
| (-) |
H — C* — CH2 — C=O — CH
| |
CH2 CH3