Structure Flashcards
How do you determine the acidity of a compound?
Comparing acidity of organic molecules can be accomplished by looking at the stability of their conjugate base.
Which is more acidic and why: Phenol or Cyclohexanol
Phenol is more acidic. The conjugate base of phenol has more resonance delocalization of its negative charge than cyclohexanol, which means that phenol has a more stable conjugate base and is more acidic than cyclohexanol.
Put the following in order of increasing acidity:
Phenol, benzoic acid, cyclohexanol
Most acidic: Benzoic acid, then Phenol, then cyclohexanol
R-COOH
Carboxylic Acid
R-COO-R
Ester
R-CO-X
Acid Halide
R-CO-NR2
Amide
R-CHO
Aldehyde
R-C=O-R
Ketone
R-OH
Alcohol
R-SH
Thiols
NR3
Amine
Name the compound
4-penten-2-ol
Name the compound:
Butanoic Acid
4-Hydroxy-3-methylbutanoic acid. If we follow IUPAC naming conventions, the highest-priority group on this molecule is the carboxylic acid because it has the highest oxidation state. We thus know that the rightmost carbon should be given the number “1” and that the suffix should be “-oic acid.” The other functional groups (“hydroxy” and “methyl”) are then listed in alphabetical order with the numbered carbon to which they are attached.
List the following from lowest to highest priroity in IUPAC naming and how did you know:
alcohol, carboxylic acid, aldehyde, amine
amine, then alcohol, then aldehyde, and finally carboxylic acid. It goes from least to most oxidized
Name the compound:
trans-4-methyl-2-hexene. The double bond takes priority when numbering.The parent chain is six carbons long, giving us the “hex” root. Since there is a double bond, it will have the “-ene” suffix. The double bond should be at the lowest number carbon possible, so numbering begins at the left end of the parent chain, and the alkene therefore begins at the second carbon. Because the two hydrogens are on opposite sides of the alkene double bond, it is in the trans configuration.
Name the following compound:
3-methyl-4-pentyne-2,3-diol
Why does hydrogenation of the following compound release 120 kj but if you were to hydrogenate benzene it wouldnt release 120 x 3?
The following wouldn’t happen. It would only release about 200 kJ/mol because benzene is resonance stabilized. Resonance made the internal energy of benzene lower so it had less energy available to release.
Why are carboxylic acids stronger than alcohols?
Resonance stabilization
What is the definition of aromatic?
Aromatic compounds are those that contain planar, conjugated rings and follow Hückel’s rule, which stipulates that the system must possess 4n + 2 pi electrons
Considering only carbon-carbon bonds, how does the bond length between ring carbons on the structure differ from the length of the single bonds outside of the ring?
The ring component of serotonin is aromatic; additionally, it displays resonance, allowing each C-C bond to display a bond order of 1.5. In other words, these bonds are halfway between single and double bonds. Higher order bonds have a greater bond energy than single bonds - that means that the heat energy required to break the bond is greater (with triple bonds requiring the most energy). Remember, bonds with higher bond dissociation energies are shorter and stronger.
What are the bond orders for single, double, and triple bonds?
In a covalent bond between two atoms, a single bond has a bond order of one, a double bond has a bond order of two, a triple bond has a bond order of three, and so on
Name the structure:
2,2-dichloro-3-phenylpropanoic acid
