Organic chemistry ii revision questions and answers
- Define the following terms
- Chiral carbon- a carbon atom that is attached to four different types of atoms or group of atoms
- Optical isomers- Kind which contain the same number and kinds of atoms but different spatial arrangements and non-commercial,suprimposable mirror images.
- Racemic mixture-a mixture that has equal amounts of left and right handled enantiomers of a chiral molecule. -A solution in which both enantiomers are present in equal amounts.
- Antiaromatic- molecules are cyclic systems containing alternating single and double bonds where the pi electron energy is higher than that of its open chain counterpart.
- Give two chemical characteristics of benzene that confirm it is more stable than ordinary alkenes.
- There are delocalized electrons above and below the plane ring.
- Benzene resists addition reactions because those reactions would involve delocalization.
- State three criteria for aromaticity as stipulated by huckel’s rule
- The molecule is cyclic (a ring of atoms).
- The molecule is planner (all the molecule lie in the same plane).
- The molecule is fully conjugated ( p orbital at every atom in the ring).
- The molecule has 4n+2 electrons.
- Give two reasons why ethers are generally used as solvents.
- Ethers can dissolve in both polar and non-polar solvents.
- Ethers has no acidic protons so basic compounds like grignard reagents are stable.
- With respect to B.p, ethers resemble alkanes more than alcohols, but with respect to solubility in H2O, ethers resemble alcohols more than alkanes. Explain.
- The carbon-oxygen bond in ethers are polar. the weak polarity of ethers do not appreciably affect their boiling points which are comparable to those alkanes of comparable molecular mass.
- they have low boiling points than alcohols because alcohol molecules are associated by hydrogen bonds while ethers are not.
Share through
