MCAT organic

MCAT CONCEPT CHECK 1.3 1. What is the difference between an aldehyde and a ketone? 2. What suffixes are used for aldehydes and ketones; how are carbonyl groups named as a substituent? 3. Fill in the common names in the following chart. 4. For a molecule with a double bond, an aldehyde, and an alcohol, which functional group would determine the suffix when naming

1. An aldehyde has a carbonyl group at the end of the chain. A ketone has a carbonyl group somewhere in the middle of the carbon chain. Another way to think of this is that the carbonyl carbon of an aldehyde has at least one bond to a hydrogen atom, whereas the carbonyl carbon of a ketone is always bonded to two other carbons. 2. Aldehydes are referred to with the suffix -al, while ketones are given the suffix -one. Carbonyl groups of both aldehydes and ketones are labeled as oxo-substituents (ketones may also be called keto-substituents). 3. Pic 4. 4. Ketones and aldehydes both take precedence over both alcohols and hydrocarbon chains, and the functional group that is the highest priority determines the suffix. Because the aldehyde is chain-terminating and therefore on carbon number 1, the aldehyde would determine the suffix when naming this compound.

MCAT CONCEPT CHECK 2.2 1. What is the difference between a conformational and a configurational isomer? 2. Consider the six pairs that the following four molecules can make. Which pairs are enantiomers? Diastereomers?

1. Conformational isomers are stereoisomers with the same molecular connectiv-ity at different points of rotation around a single bond. Configurational isomers are stereoisomers with differing molecular connectivity. 2. Enantiomers are nonsuperimposable mirror images. That means the molecules must be mirror images that are different from one another (superimposable mirror images represent the same object). The molecules on the top-left and bottom-right are nonsuperimposable mirror images and therefore enantiomers. The same is true for the top-right and bottom-left. All other combinations are diastereomeric because the pairs differ at some, but not all, stereocenters.

MCAT CONCEPT CHECK 1.2 1. Fill in the correct names for the alkanes listed below. If more than one com-pound can be described with a given molecular formula, name the straight-chain alkane to which the formula refers and draw one alternative. 2. In a molecule with two double bonds adjacent to each other and an alcohol, which functional group would take precedence in naming?

1. Pic. Butane and all hydrocarbons that are larger than butane may have a branched appearance, which shortens the parent chain. An example is isobutane, properly named methylpropane, shown here. Any branched hydrocarbon with the correct number of carbons and no multiple bonds or rings is correct (pic of this on next slide)\ 2. The alcohol would take precedence because the carbon to which it is attached has a higher oxidation state.

MCAT CONCEPT CHECK 2.1 1. What property or properties do structural isomers have in common? 2. Of the compounds cyclopropanol, 2-propanol, acetone, and prop-2-ene-1-ol, which are structural isomers of each other?

1. Structural isomers share a molecular formula, and not necessarily anything else. 2. Cyclopropanol, acetone, and prop-2-ene-1-ol are all structural isomers of each other with the chemical formula C3H6O. 2-Propanol has the chemical formula C3H8O.

MCAT CONCEPT CHECK 1.4 1. What would be the names of the ester, amide, and anhydride derivatives of pentanoic acid? Assume that the R group on the ester is -CH3 and that the amide is unsubstituted • Ester: • Amide: • Anhydride: 2. Name the following compound:

1. The ester derivative would be methyl pentanoate. The amide would be pentanamide. The anhydride would be pentanoic anhydride. 2. 3-methyl-2-oxopentanoic acid

3. What is a meso compound? 4. Complete the Newman projection for the following compound:

3. A meso compound contains chiral centers but also has an internal plane of symmetry. This means that the molecule is overall achiral and will not rotate plane-polarized light. 4. Answer is below

3. Is the following compound a geminal diol or a vicinal diol? 4. What are the common names for 2-propanol and ethanol?

3. Diols are alcohols with two hydroxyl groups. In a geminal diol, these hydroxyl groups are on the same carbon (gemini derives from the Latin for "paired, twins"). In a vicinal diol, the hydroxyls are in the vicinity of each other—on adjacent carbons (vicinus derives from the Latin for "neighbor"). Thus, the com-pound shown is a geminal diol. 4. Isopropyl alcohol and ethyl alcohol, respectively

3. What are physical properties? Give three examples of physical properties 4. What are chemical properties

3. Physical properties are aspects of a compound that do not play a role in changing chemical composition. Examples include melting point, boiling point, solubility, odor, color, and density. 4. Chemical properties are aspects of a compound that change chemical composition; in organic chemistry, chemical properties are usually dictated by the reactivity of various functional groups