Quiz 1 Flashcards
how do you produce a compound with just single bonds from a terminal alkyne
H2, Pd/C
how do you produce a compound with X on the most substituated carbon and a double bond on the terminal position from a terminal alkyne
HX where X = Cl, Br, or I
how do you produce a compound with only single bonds and two Xs located on the same carbon from a terminal alkyne
xs HX
how do you produce a compound with a double bond on the terminal position and one X is on one of the double bonded carbons, while the other X is on the other double bonded carbons from a terminal alkyne
Br2 or Cl2
how do you produce a compound with just single bonds and two Xs on one carbon and two Xs on the other carbon from a terminal alkyne
xs Br2 or Cl2
how do you produce a compound with the triple bond and a new R group formed from a terminal alkyne
- NaNH2
- RCH2Br
how do you produce an aldehyde (double bond on oxygen) from a terminal alkyne
- 9-BBN
- H2O2, HO-
how do you produce a ketone from a terminal alkyne
H2O, H2SO4
HgSO4
how do you reduce a compound from a triple bond to a double bond for a terminal alkyne
H2
Lindlar catalyst
how do you produce a compound with just single bonds from a internal alkyne
H2, Pd/C
how do you produce a ketone from an internal alkyne
- BH3
- H2O2, HO-
how do you produce a compound with an internal double bond and an X on one of the double bond carbons, while the other X is on the other double bonded carbon from an internal alkyne
Br2 or Cl2
how do you produce a compound with just single bonds and two Xs on one carbon and two Xs on the other from a internal alkyne
xs Br2 or Cl2
how do you produce a compound with an internal double bond and an X bonded to one of the carbons from an internal alkyne
HX
how do you produce a compound with just single bonds and two Xs bonded to one internal carbon from an internal alkyne
xs HX
how do you produce a cis alkene from a internal alkyne
H2
Lindlar catalyst
(syn addition)
how do you produce a trans alkene from an internal alkyne
Na or Li, NH3
(anti addition)
how to turn a terminal alkyne to an internal alkyne
adding the group you want (THE TRIPLE BOND STAYS AS A TRIPLE BOND)
- NaNH2
- RCH2Br
how to turn an internal alkyne to a terminal alkene
ozonolysis: cuts the double bond in half and puts an oxygen on the double bond, turning it into a aldehyde
- O3
- Zn, CH3CO2H
what is acetylene
H-C triple bond C-H
how do you produce a compound with just single bonds and an OH bonded to an internal carbon from a terminal alkene
H2O, H2SO4
how do you produce a compound with just single bonds and an OH bonded at the end from a terminal alkene
- BH3
- H2O2, HO-
how do you produce a compound with just single bonds and an X bonded to an internal carbon, and another X bonded to the other carbon from a terminal alkene
Br2 or Cl2
how do you produce a compound with just single bonds and an OH bonded to an internal carbon, and another X bonded to the other carbon from a terminal alkene
Br2 or Cl2
H2O
Characteristics of a triple bond
- bond angle of 180 degrees
- short carbon carbon bond of 120 A (very short)
- strong bond of 231 kcal/mol (very strong)
rank the stability of carbocations from MOST to LEAST stable
Most
- tertiary carbocation
- secondary carbocation
- secondary vinylic cation (ab the same stability as the next one)
- primary carbocation
- primary vinylic cation (about the same stability as the next one)
- the methyl cation
Least
dihalide vs. tetrahalide
dihalide: one halide (Br or Cl) group
tetrahalide: two halides on one carbon (AKA geminal)
why do two halides end up on the same carbon?
to improve stability (e- sharing)
keto-enol tautomerism
to produce a ketone, an enol is formed first (instead of an O double bond, it has an OH group), but the enol is nearly impossible to isolate.
tautomerism
are structural isomers (constitutional isomers) of chemical compounds that readily interconvert (differ by the location of a double bond and a hydrogen atom)
internal vs. terminal for need of a catalyst or not and why
internal: no need for a catalyst
terminal: needs a catalyst to help it get over the activity threshold since it’s not as e- rich (the more alkyl groups present, the more e- they can donate). Terminal alkynes are also less reactive.
why is a trans product produced?
because 9-BBN is so big it creates steric repulsion (the bulky groups go on opposite sides)
high pKa vs. low pKa
low pKa = easy to remove proton (stronger acid)
high pKa = difficult to remove proton (stronger base)
ethyne pKa (HC triple bond HC)
25
ethene pKa (H2C=CH2)
44
ethane pKa (CH3CH3)
greater than 60
why is the stability like this: alkyl group (sp3 hybridized) (least stable), a vinylic group (sp2 hybridized), and acetylide anion (sp hybridized) (most stable)
alkyl groups: 25 % s character
vinylic groups: 33 % s character
acetylide anion: 50 % s character
pKa of H2O
15.7
pKa of HF
3.2
pKa of NH3
36
