9/26 Flashcards
what does a C=O bond in a carbonyl create? Why is this useful?
it creates an electrophilic carbon center that can be attacked by nucleophiles
what is the intermediate that forms when a nucleophile attacks a carbonyl?
a tetrahedral intermediate with a alkoxide ion
what are the types of nucleophiles that can attack a carbonyl
hydrides and organometallic compounds
what is LAH (lithium aluminum hydride) used for
it is a source of hydride, it is an extremely strong reducing agent and can reduce carboxylic acids, esters, ketones, and aldehydes but it is very dangerous and will violently react with water or alcohol solvents (acidic protons)
what is NaBH4 used for (sodium borohydride)
it is a source of hydride, it is a weak reducing agent and can only reduce ketones or aldehydes
what type of nucleophiles do organometallic compounds make
they make carbanion like nucleophiles
when carbon is bonded to magnesium or lithium what happens to the polarity and reactivity of the carbon
the polarity is swapped and the carbon is more negatively charged, this makes it act as a nucleophile with a carbanion like character
what is reduction in organic chemistry
it is the increase in hydrogen content and the decrease of oxygen content (a C=O may become C-O, or an oxygen is lost)
What is oxidation in organic chemistry
it is the decrease in hydrogen content and the increase in oxygen content (C-O may become O=C, or addition of oxygens)
what can primary alcohols be oxidized to
aldehydes and carboxylic acids
what can carboxylic acids and aldehydes be reduced to
primary alcohols
what does LAH reduce a ketone to?
a 2° Alcohol
what does LAH reduce at carboxylic acid to?
a aldehyde and then a 1° Alcohol
what does LAH reduce a aldehyde to?
a 1°alcohol
what are the reagents for LAH
1.) LAH, Et2O or THF
2) H30 (workup)
why do we need to be cautious when using hydrides as a reagent?
in LAH, the hydride can act as a nucleophile and a base, meaning it can undergo violent exothermic acid base chemistry when used in a solvent with an acidic hydrogen (H20 or alcohols)
when using LAH, what solvent should you use?
an ether like THF or Diethyl Ether (Et2O)
if you wanted to selectively reduce a carbonyl, what reagent should you use
NaBH4
what are esters reduced to
primary alcohols
what are the common solvents for a reduction with LAH
Tetrahydrofuran (THF), Et2O (diethyl ether), CH2Cl2 (dichloromethane)
what is the hardest carbonyl to reduce
carboxylic acids
whats the easiest carbonyl to reduce
aldehyde
what should we use if we want a selective reduction of a carbonyl
we use NaBH4 which is a weaker reducing agent
what is the swern oxidation
it synthesizes aldehydes and ketones using DMSO and (COCl)2 and triethyl amine
what does PCC do
it oxidizes primary alcohols to aldehydes
what is reagent for PCC
PCC in Ch2Cl2
If you react a primary alcohol with KMnO4, OH/ H20 and heat, what do you get
a carboxylic acid
if you react CrO3 / H2So4 with a primary alcohol, what do you get
a carboxylic acid
if you react CrO3/ H2SO4 with a secondary alcohol what do you get
a ketone
what does the jones oxidation do
it makes an alcohol into a carboxylic acid or a ketone with CrO3 and H2SO4
how is H2CO4 generated
in situ with CrO3 and H2SO4
what indicates a jones reaction
the orange solution turns green after oxidation
why are organometallics important
they form carbon carbon bonds
what is a grinard reagent
a Carbon-Mg bond characterized by its carbanion like feature (polarity swap)
what do you need to make a grignard reagent
an alkyl halide, Magneisum, and Diethyl ether (Et2O)
what is an umpolung
the reversal of polarity in a chemical reaction
what are the reagents for swern oxidation
1) DMSO and oxalyl chloride (COCl)2
2) triethyl amine
what are the reagents for pyridnium chloro chromate
1) PCC in CH2Cl2 solvent
when reacting an ester with a grignard reagent, what is the result?
you will get a tertiary alcohol
