Question
In 2006, an adduct between a phosphine and a borane was shown to be the first metal-free catalyst to hetero·lyze this molecule. For 10 points each:
[10e] Name this elemental gas that must otherwise be activated by an expensive rare metal like platinum before it can convert alkenes to alkanes.
ANSWER: hydrogen gas [or molecular hydrogen; or H2]
[10m] The phosphine-borane catalyst is a sterically hindered Lewis pair described by this adjective. This term also describes crystals that can’t rearrange to a zero-entropy state because of geometric constraints.
ANSWER: frustrated [or geometrical frustration; accept frustrated Lewis pairs]
[10h] Frustrated Lewis pairs are particularly useful asymmetric catalysts for this common functional group interconversion, which is done without stereo·specificity using the reagent Na·BH3·CN. We’re looking for an answer like “converting ketones to enols.”
ANSWER: converting imines to amines [or reducing imines to amines; accept Schiff bases in place of “imines”; prompt on answers that only mention imines; prompt on reduction or reducing; prompt on reductive amination; reject “converting amines to imines”] (The formula is for sodium cyanoborohydride.)
<Chemistry>
Summary
| 2023 ACF Nationals | 04/22/2023 | Y | 24 | 15.42 | 67% | 67% | 21% |
Data
| Chicago B | Florida A | 10 | 10 | 0 | 20 |
| Harvard A | Chicago C | 10 | 10 | 10 | 30 |
| MIT A | Cornell B | 10 | 10 | 0 | 20 |
| Imperial A | Houston A | 10 | 0 | 0 | 10 |
| North Carolina A | Indiana A | 10 | 10 | 10 | 30 |
| Northwestern A | Columbia A | 10 | 10 | 0 | 20 |
| Virginia A | South Carolina A | 0 | 0 | 0 | 0 |
| UC Berkeley A | Minnesota A | 10 | 10 | 10 | 30 |
| Brown A | Georgia Tech A | 10 | 10 | 10 | 30 |
| Claremont A | WUSTL B | 10 | 0 | 0 | 10 |
| Maryland A | Cornell A | 0 | 10 | 0 | 10 |
| Georgia Tech B | Illinois A | 0 | 10 | 0 | 10 |
| Penn State A | Rutgers A | 0 | 0 | 0 | 0 |
| Toronto A | Texas A | 0 | 10 | 0 | 10 |
| Yale A | WUSTL A | 10 | 10 | 0 | 20 |
| Vanderbilt A | Florida B | 10 | 10 | 10 | 30 |
| Penn A | Iowa State A | 10 | 0 | 0 | 10 |
| Columbia B | Johns Hopkins A | 10 | 10 | 0 | 20 |
| McGill A | Yale B | 0 | 0 | 0 | 0 |
| Stanford A | Ohio State A | 10 | 10 | 0 | 20 |
| Rutgers B | Purdue A | 0 | 0 | 0 | 0 |
| UC Berkeley B | NYU A | 10 | 10 | 0 | 20 |
| Chicago A | Duke A | 0 | 10 | 0 | 10 |
| Minnesota B | Michigan A | 10 | 0 | 0 | 10 |