1 • Additional Problems
1 • Additional Problems
The following model is a representation of citric acid, the key substance in the so-called citric acid cycle, by which food molecules are metabolized in the body. Only the connections between atoms are shown; multiple bonds are not indicated. Complete the structure by indicating the positions of multiple bonds and lone-pair electrons (black = C, red = O, gray = H).
The following model is a representation of acetaminophen, a pain reliever sold in drugstores under a variety of names, including Tylenol. Identify the hybridization of each carbon atom in acetaminophen, and tell which atoms have lone pairs of electrons (black = C, red = O, blue = N, gray = H).
The following model is a representation of aspartame, C14H18N2O5, known commercially under many names, including NutraSweet. Only the connections between atoms are shown; multiple bonds are not indicated. Complete the structure for aspartame, and indicate the positions of multiple bonds (black = C, red = O, blue = N, gray = H).
Electron-Dot and Line-Bond Structures
What is the shape of benzene, and what hybridization do you expect for each carbon?
Pyridoxal phosphate, a close relative of vitamin B6, is involved in a large number of metabolic reactions. What is the hybridization and the bond angle for each nonterminal atom?
Quetiapine, marketed as Seroquel, is a heavily prescribed antipsychotic drug used in the treatment of schizophrenia and bipolar disorder. Convert the following representation into a skeletal structure, and give the molecular formula of quetiapine.
Why do you suppose no one has ever been able to make cyclopentyne as a stable molecule?
Allene, H2CCCH2, has two adjacent double bonds. Draw a picture showing the orbitals involved in the σ and π bonds of allene. Is the central carbon atom sp2- or sp-hybridized? What about the hybridization of the terminal carbons? What shape do you predict for allene?
Complete the electron-dot structure of caffeine, showing all lone-pair electrons, and identify the hybridization of the indicated atoms.
Most stable organic species have tetravalent carbon atoms, but species with trivalent carbon atoms also exist. Carbocations are one such class of compounds.
A carbanion is a species that contains a negatively charged, trivalent carbon.
Divalent carbon species called carbenes are capable of fleeting existence. For example, methylene, :CH2, is the simplest carbene. The two unshared electrons in methylene can be either paired in a single orbital or unpaired in different orbitals. Predict the type of hybridization you expect carbon to adopt in singlet (spin-paired) methylene and triplet (spin-unpaired) methylene. Draw a picture of each, and identify the valence orbitals on carbon.
Two different substances have the formula C3H6. Draw both, and tell how they differ.
Among the most common over-the-counter drugs you might find in a medicine cabinet are mild pain relievers such ibuprofen (Advil, Motrin), naproxen (Aleve), and acetaminophen (Tylenol).