30 Fill-in-the-Blank Questions — OC-02

1. The general formula for alkanes is ________ (answer: Cₙ$H_{2}$ₙ₊_{2})
2. The dihedral angle in the staggered conformation of ethane is ________ (answer: 60°)
3. The most stable conformation of butane is ________ with a dihedral angle of ________ (answer: anti; 180°)
4. The least stable conformation of butane is ________ because the ________ groups directly eclipse each other. (answer: fully eclipsed; methyl)
5. Free radical halogenation proceeds in three steps: ________, ________, and ________. (answer: initiation, propagation, termination)
6. In initiation, $X_{2}$ is cleaved by ________ to give ________ radicals. (answer: UV light or heat; halogen)
7. Hydrogen abstraction reactivity follows: ________ > ________ > ________. (answer: 3°; 2°; 1°)
8. The most selective halogen in free radical halogenation is ________, while the most reactive is ________. (answer: $Br_{2}$; $F_{2}$)
9. Markovnikov's rule: in addition of HX to an unsymmetrical alkene, H adds to the carbon with ________ H atoms. (answer: more)
10. Propene + HBr (no peroxide) → ________ (SMILES). (answer: CC(Br)C / 2-bromopropane)
11. Anti-Markovnikov addition of HBr to propene requires ________. (answer: organic peroxide/ROOR)
12. Anti-Markovnikov addition works ONLY with ________, NOT with HCl or HI. (answer: HBr)
13. Anti-Markovnikov addition with HCl fails because the Cl• radical addition step is ________. (answer: endothermic)
14. Anti-Markovnikov addition with HI fails because I• is too ________, causing premature ________. (answer: reactive; chain termination)
15. Propene + HBr + ROOR → ________ (SMILES). (answer: CCCBr / 1-bromopropane)
16. Reductive ozonolysis of an alkene uses ________ as the workup reagent. (answer: Zn/$H_{2}$O)
17. Reductive ozonolysis (Zn/$H_{2}$O) of an alkene gives ________ and/or ________ as products. (answer: aldehydes; ketones)
18. 2-Butene (CC=CC) on reductive ozonolysis gives ________ molecules of ________. (answer: 2; acetaldehyde/ethanal/$CH_{3}CHO$)
19. Terminal alkynes are more acidic than alkenes because the sp C–H bond has ________% s-character. (answer: 50)
20. The acidity order is: ________ > ________ > ________ (sp vs $sp^{2}$ vs $sp^{3}$ C–H). (answer: alkyne > alkene > alkane)
21. A terminal alkyne reacts with NaN$H_{2}$ to give ________ (sodium acetylide) + ________. (answer: RC≡C^{-}$$Na^{+}; $NH_{3}$)
22. Lindlar's catalyst = Pd deposited on ________, poisoned with ________ and ________. (answer: $CaCO_{3}$; Pb(OAc)_{2}; quinoline)
23. Lindlar's catalyst reduces an internal alkyne to the ________ alkene by ________ addition. (answer: cis; syn)
24. Na in liquid $NH_{3}$ reduces an internal alkyne to the ________ alkene by ________ addition. (answer: trans; anti)
25. The mechanism of Na/liq. $NH_{3}$ reduction of alkynes is called ________ reduction and proceeds via a ________ anion intermediate. (answer: dissolving metal/Birch-type; radical)
26. The relative energy of gauche-butane above anti-butane is approximately ________ kJ/mol. (answer: 3.8)
27. The SMILES for cis-but-2-ene is ________ and for trans-but-2-ene is ________. (answer: C/C=C\C; C/C=C/C)
28. $H_{2}$O addition to an alkene in dilute H_{2}$$SO_{4} follows ________ rule. (answer: Markovnikov's)
29. The intermediate in $Br_{2}$ addition to an alkene is a ________ ion, leading to ________ addition. (answer: bromonium; anti)
30. The mnemonic for butane conformation stability order is ________. (answer: A Gentle Evening Falls / Anti > Gauche > Eclipsed > Fully eclipsed)