Ch 10 Alcohols Flashcards
synthesis gas
CO2 + 2 CO + 4 H2
Nucleophilic Substitution on an Alkyl Halide
Usually via the SN2 mechanism; competes with elimination. Inversion of stereochemistry.
Grignard reagent
The organomagnesium halides, of empirical formula R - Mg - X
synthesis of a Grignard reagent
synthesis of a Grignard reagent
synthesis of a Grignard reagent
what kind of solvent is required to synthasise a Grignard reagent?
a solvent containing the ether funtional group
THF
describe the formation of the Grignard reagent
Grignard and organolithium reagents provide some of the best methods for assembling a carbon skeleton. These strong nucleophiles add to ketones and aldehydes to give alkoxide ions, which are protonated to give alcohols.
Formation of the Grignard reagent: Magnesium reacts with an alkyl halide in an anhydrous ether solution.
Explain the first step in carbon skeleton formation using a pre-made Grignard or organolithium reagent
Reaction 1: The Grignard reagent attacks a carbonyl compound to form an alkoxide salt.
Explain the second step in carbon skeleton formation using a pre-made Grignard or organolithium reagent
Reaction 2: After the first reaction is complete, water or dilute acid is added to protonate the alkoxide and give the alcohol.
How would you form a primary alcohol?
Addition of a Grignard reagent to formaldehyde
Acid-catalysed hydration. Markovnikov orientation, syn addition.
convert alkene to epoxide (diol), syn addition
Syn Dihydroxylation.
Osmium tetroxide (OsO4) and peroxides (H2O2)
-or-
Potassium permanganate (KMnO4) and hydroxide ion (-OH) (cold, dilute)
Convert an alkene to an alcohol with Markovnikov orientation.
Acid-catalysed hydration.
convert an alkene to an alcohol with Markovnikov orientation, anti addition.
Oxymercuration–demercuration. Hg(OAc)2 + H2O.
convert an alkene to an alcohol, anti-Markovnikov orientation, syn addition.
Hydroboration–oxidation with peroxides.
(1) BH3 •THF, (2) H2O2, NaOH
convert alkene to epoxide (diol), anti addition
Anti Dihydroxylation. peroxy acid (HCO3H) and hydronium (H3O+)
convert grignard into a secondary alcohol with one additional carbon
Addition of a Grignard or organolithium reagent to an aldehyde.
(1) ether, (2) hydronium (H3O+)
convert grignard into a primary alcohol with one additional carbon
Addition of a Grignard or organolithium reagent to formaldehyde.
(1) ether, (2) hydronium (H3O+)
convert grignard into a tertiary alcohol with one additional carbon, with one of the final three R groups derived from the grignard reagent.
Addition of a Grignard or organolithium reagent to a ketone.
(1) ether, (2) hydronium (H3O+)
convert grignard into a tertiary alcohol with one additional carbon, with two of the final three R groups derived from the grignard reagent.
Addition of a Grignard or organolithium reagent to an ester or acid halide (Cl shown).
(1) ether, (2) hydronium (H3O+)
aldehyde to alcohol with no extra carbons added
NaBH4 (mild sauce)
or
LiAlH4 (hot sauce)
ketone to alcohol with no extra carbons added
NaBH4 (mild sauce)
or
LiAlH4 (hot sauce)
convert grignard into a primary alcohol with two additional carbons
Addition of a Grignard or organolithium reagent to ethylene oxide (an epoxide).
(1) ether, (2) hydronium (H3O+)
carboxcylic acid anion in base to alcohol with no extra carbons added
LiAlH4 (hot sauce) ONLY
NaBH4 (mild sauce) NO RXN!
ester to alcohol with no extra carbons added
LiAlH4 (hot sauce) ONLY
NaBH4 (mild sauce) NO RXN!
Raney Nickel works like hot sauce (LiAlH4), but also hydrates and reduces carbon double bonds (C=C), making the product an alkane alcohol
