Term
| Which is a weaker bond: pi or sigma? |
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Definition
| Pi bond since they are side-by-side overlapping of orbitals. sigma bonds have maximum overlap creating a stronger bond. |
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Term
| What is the approximate O-C-O bond angle in the ester functional group? |
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Definition
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Term
| Excluding stereoisomers, how many mono-brominated compounds can be made from 2,5-dimethylhexane? |
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Definition
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Term
| What must happen for a molecule to have chirality? |
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Definition
| It must have asymmetric carbons (chiral centers) without an internal mirror image. Compounds with an internal mirror image are meso compounds. |
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Term
| How do enantiomers differ chemically? |
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Definition
| They have all of the same physical properties except that they rotate plane-polarized light in opposite directions (optically active) and interact with specific enzymes differently. |
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Term
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Definition
| Stereoisomers that are not mirror images. |
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Term
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Definition
| Stereoisomers that are mirror images of each other. |
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Term
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Definition
| Isomers that have the same connectivity but differ in the arrangement of their atoms in space. |
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Term
| What are constitutional isomers? |
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Definition
| Isomers whose atoms have a different connectivity. |
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Term
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Definition
| Different compounds with the same molecular formula. |
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Term
| What direction does the r configuration take priority? |
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Definition
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Term
| What direction does the s configuration take priority? |
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Definition
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Term
| How can you tell that you have a meso compound? |
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Definition
| There happens to be a mirror image down the center of the molecule. Adjacent carbons can have the same substituents with different configuration. |
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Term
| What does levorotatory mean? Dextrorotatory? |
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Definition
| Levorotatory means that the compound rotates plane polarized light to the left. Dextrorotatory rotates the plane polarized light to the right. |
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Term
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Definition
| There are equal concentrations of both mixtures of R and S configurations of the molecule. |
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Term
| A solution of 200mg of the R enantiomer of a substance had an observed rotation of a=8 degrees. If 50mg of the S enantiomer of the substance is dissolved into the same solution, the new observed rotation that would be measured would be: A. -8 degrees, B. -2 degrees, C. 6 degrees, D. 4 degrees? |
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Definition
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Term
| What is a stronger acid and why: Phenol or a carboxylic acid? |
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Definition
| Carboxylic acids are stronger acids since although both compounds have resonance stabilized conjugate bases, the phenol conjugate base requires the aromaticity of the phenol ring to be broken which is not as favorable as the identical resonance structures that the carboxylic acid conjugate base creates. |
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Term
| Which creates the strongest acid: tertbutanol, butanol, or secbutanol? |
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Definition
| Tertbutanol since the inductive effects of the three methyl groups cause a slightly greater stabilization effect of the conjugate base. |
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Term
| Which is the strongest base? Ammonia, primary amines or secondary amines? |
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Definition
| Secondary amines because the carbon alkyl groups act as electron donors and thereby stabilize the conjugate acid. |
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Term
| Why are alkynes more acidic than alkenes and alkanes? |
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Definition
| Alkynes have sp hybridization on the terminal carbon. The resultant negative charge is thus more tightly held due to the greater s character of the hybridization. The great electron density present in the tripple bond also creates sort of an electron-withrawing/inductive effect. Resonance plays no role in its acidity. |
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Term
| What is more stable, a highly substituted alkene or the same alkene with only hydrogen substituents? |
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Definition
| The more highly substituted alkene gives off the lowest heat of hydrogenation and therefore is more stable. |
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Term
| How many electrons does an aromatic ring have? |
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Definition
| 4n+2 electrons in pi orbitals |
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Term
| What does a Tollen's reagent tell us? |
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Definition
| The Ag+ becomes reduced to elemental silver in the presence of reducing sugar to yield a silver "mirror". If the sugar is non-reducing, no silver comes out of solution and we can conclude that it is a polysaccharide or includes an ether. |
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