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106 Cards in this Set
- Front
- Back
Enantiomers
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Stereoisomers that are non superimposable mirror images
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Diastereomers
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Stereoisomers that are NOT mirror images of each other
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How many different groups are needed for a central Carbon atom to be considered Chiral?
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4
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How is a Chiral and Achiral central carbon different?
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A Chiral has 4 different moleclules attached to the central C while the Achiral central C has a plain of semitry
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How many chiral carbons are needed on a molecule to make the molecule chiral?
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Just one
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Define Optical Activity
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It is that organic molecules rotate plane polarized light.
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Enantiomers have atleast 2 forms.
1 rotates light (-) _____ ______ 2 rotates light (+)_____ ______ |
(-) left - Levorotatory
(+) right - Dextrotatory |
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Do Achiral molecules rotate light?
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No
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Do Chiral molecules rotate light?
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Yes
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Who discovered Enantiomers?
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Louis Pasteur
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In IUPAC naming,
R =? S =? |
Clockwise
Counter clockwise |
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In IUPAC naming you take the lowest priority attached atom to the central C and point it?
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Away from you
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If you have a molecule with one chiral center it will have?
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enantiomers (mirror images)
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If you have a molecule with more than one chiral center you will have?
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A possiblity of diastereomers (non mirror images)
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The Threonine isomer that is naturally occuring and is an amino acid for our bodies is the ____isomer
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2S,3R
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Three things needed to be chiral?
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Central C atome with 4 different attached molecules
No plane of Semitry Tetrahedral |
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2R,3R -->2R,3S =
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Diastereomers
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2S,3S --> 2R,3S =
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Diastereomer
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2R,3R --> 2S,3S =
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Enatiomer
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2R,3S --> 2S,3R =
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Enatiomer
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You can tell if the molecule has a MESO form if it has _____?
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A plane of symetry.
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If the molecule is MESO does it have Optical activity?
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No
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If the molecule is MESO is it chiral?
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No, its the same molecule?
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What is a Racemic Mixture?
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A mixture of 50:50 R,S enantiomers
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How do you prepare a Alkyl Halide?
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you make them from alcohols
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When making Alkyl Halides, which has best reactivity: tertiary, secondary, primary, or methyl.
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tertiary, Because SN1 rxn happens under neutral or acidic conditions and favors tertiary (Fast for SN1)
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Primary and secondary alcohols work best with what molecules?
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PBr3 and SOCl2
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When making Alkyl Halides from tertiary alcohols, what should you use?
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HX
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What is a Grignard Reaction?
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They are a carbon metal bond.
R-Mg-X = a magnesium halide (-)(+) |
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What do they mean when they say an organometallic compound?
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It means the metal is in the middle.
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In Gringnard Reactions, what halide can NOT be used?
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F
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In Gringnard Reactions, what halides can be used?
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Cl, Br, and I
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In nucleophilic Substitutions Reactions, Alkyl Halides are generally electrophiles or nucleophiles?
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electrophiles.
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If the Alkyl Halides are electrophilic, they either do 1 of 2 things, what are they?
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1. substitution of X
2. elimination of HX (which equals an alkene so done't forget the double bond) |
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In substitution, the X is _______ by the OH-?
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Replaced, X is the leaving group and leaves a + charge that the OH- take.
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In elimination, the X is ________ by the OH-?
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eliminated, the X leaves and the OH- takes an H, makes H2O and the alkene is formed.
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Nucleophilis Substitution Rxn occurs by 2 pathway:
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1. SN1
2. SN2 |
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In SN reactions a nucleophile (Nu:-) reacts w/ a __________ and substitutes for a leaving group.
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substrate (R-X), the X is replaces into (R-Nu)
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In SN rxns, when Nu: is (-) the product is?
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Neutral
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In SN rxns, when Nu: has no charge the product is?
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Positive
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When MAKING an alkyl halide:
1. Tertiary alcohols use what chemical for transformation? 2. Secondary & Primary use what chemical for transformation? |
1. H-X
2. SOCl2 or PBr3 |
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The SN2 reaction takes place in how many steps?
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One step w/o an intermediate
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In an SN2 reaction the NU: attacks where?
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the back 180 from the X or LG
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SN2 reactions the rate is determined by?
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The concentration of the substrate (alkyl haildie) and the nucleophile
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In an SN2 rxn, when the NU: attacks from the back it changes the molecules?
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configuration
From an S to an R or vice versa |
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Common LG for an SN2 rxn are?
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I-, Br-, Cl-
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SN1 Reactions take place in what type of C substrate?
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tertiary
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SN1 Reactions work in what type of environment?
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Neutral or acidic
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in an SN1 reaction is there an intermediate?
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yes
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How many steps in an SN1 reaction
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2 steps
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In an SN1 reaction how does the leaving group leave?
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spontaniously
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In an SN2 reaction how does the leaving group leave?
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as the Nu attacks the substrate, the LG group gets pushed off. This happens all at the same time that is why there is no intermediate.
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The rate of an SN1 reaction depends on the?
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Concentration of the substrate only
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in an SN1 reaction, the Nu: can attack from where? and what does this make?
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either side, because the LG is gone.
a racemic mixture 50:50 |
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What are the LG groups in an SN1 reaction?
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Same as SN2, Cl-, I-, Br-
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Elimination reactions almost always give mixtures of _______ products.
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alkene
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Alexander Zaitsev's Rule?
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The more highly substituated will be more prevelent in solution.
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E1, the C-X bond?
How many steps? |
Spontaniously breaks like in the SN1 (C is partially +)
2 steps (there is an intermediate) |
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E2, the C-X bond is?
How many steps? |
based induced for bond cleavage like the SN2 (C is partially -)
1 step (no intermediate) |
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E1cB, the C-X bond is?
How many steps? |
Base abstraction of the proton occurs 1st.
2 steps (there is an intermediate) |
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Don't forget, all E reactions give rise to ______?
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double bonds.
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Primary alkyl halide substitution use?
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SN2
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Primary alkyl halide eilmination (w/ OH) use?
If 2 carbons away from the carbonyl group use? |
E2
E1cB |
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Secondary alkyl halide substitution use?
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SN2
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Terteriary alkyl halide:
Basic use? Neutral use? Acidic use? Basic 2 away use? |
E2
SN1 (substitution) E1 (elimination) E1cB |
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Synthesis of an alcohol from a carbonyl cmpd is done by oxidation or reduction?
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reduction
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Synthesis of Alcohols:
Reduction of Aldehydes (R-C=O) gives __________ and uses ______ to do it. |
Primary alcohols
NaBH4 |
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Synthesis of Alcohols:
Reduction of Ketones (R-C-R, C=O) gives__________ and uses ______ to do it. |
Secondary alcohols.
NaBH4 |
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Synthesis of Alcohols:
Reduction of Carboxylic Acid (R-C-OH, C is =O) gives __________ and uses ______ to do it. |
primary alcohols
LiAlH4 |
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Synthesis of Alcohols:
Reduction of Esters (R-C-OR, C=O) gives __________ and uses ______ to do it. |
primary alcohols
LiAlH4 |
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Synthesis of Alcohols:
Formaldehyde (H2C=O) w/ a Gringnard (RMgX) gives what type of alcohol? |
Primary
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Synthesis of Alcohols:
Aldehydes (RC=O) w/ a Gringnard (RMgX) gives what type of alcohol? |
Secondary
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Synthesis of Alcohols:
Ketones (RC=O,C) w/ a Gringnard (RMgX) gives what type of alcohol? |
Teritary
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Synthesis of Alcohols:
In reduction of a carboxylic acid or ester, you add what? |
LiAlH4 - 2 H's, one in the OH (comes from [H] and one because we got rid of the double bond from H3O+.
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Synthesis of Alcohols:
in the gringnard reagent what part is the LG? |
MgX, the R stays and attaches to the new molecule.
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Reactions of Alcohols:
The dehydration of Alcohols is the? |
elimination of H2O to give an alkene.
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Reactions of Alcohols:
In Dehydration of OH, the H adds to what in the first step? |
it adds to the OH making H2O
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Reactions of Alcohols:
In Dehydration of OH, the second step H2O? |
is the LG and removes it's self leaving a positive charge behind
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Reactions of Alcohols:
In Dehydration of OH, the third step the the H2O? |
Takes an H from the molecule.
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Reactions of Alcohols:
In Dehydration of OH, the forth step, the H is now missing and what forms? |
a double bond.
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Reactions of Alcohols:
Oxidation of alcohols are the turning of what to what? |
Alcohols to carbonyl compds.
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Reactions of Alcohols:
Oxidation: Primary alcohols turn into? |
Carboxylic acid
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Reactions of Alcohols:
Oxidation: Secondary alcohols turn into? |
Ketones
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Reactions of Alcohols:
Oxidation: Tertiary alcohols turn into? |
No Rxn
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Reactions of Alcohols:
What are the 3 Oxidation reagents? |
Na2Cr2O7
CrO3 Periodinane (expensive) |
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Reactions of Alcohols:
Conversion into Ethers steps 1. 2. |
1. add Alkali metal or strong base NaH
2. add alkyl halide (Williamson ether synthesis) |
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Reactions of Alcohols:
Ethers: The best reactivity comes from what type of alkyl halides? |
Primary, the more hindered the substrates the more E2 will occur.
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Reactions of Alcohols:
Ethers: the CH3 that comes from the CH3-X is bonded to? |
The O.
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Reactions of Ethers:
can only under go one general reaction, what is it? |
CLEAVED by a strong acid. HI or HBr.
you should have 2 molecules in the end. |
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Reactions of Ethers:
SN2 pathway to do list: 1 2 |
1. check for O to be attached to primary or secondary carbons. NOT Tert.
2. the X goes with the less hindered group |
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Reactions of Ethers:
SN1 pathway to do list: 1 2 |
1. Check for O to be attached to a tert carbon.
2. X goes with tert group |
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Cyclic Ethers: Epoxides (triangle with an O)
Epoxides into Alcohols: how easily can they be cleaved? |
Very easily, they are unstable due to strain.
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Cyclic Ethers: Epoxides
how are epoxides cleaved? |
by an acid, base, grignard (RMgX), Nu:
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Cyclic Ethers:Epoxides
Cleaved by HX what happens |
OH in the opening and the X opposite side for trans stereochemistry
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Cyclic Ethers:Epoxides
Cleaved by H3O+ what happens |
OH in the opening and another OH in the trans position.
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The Nature of Carbonyl Cmpds:
List the 2 groups of carbonyl compounds based on the chemistry they undergo: |
1. Aldahydes and Ketones
2. Carboxylic Acids and derivites |
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The Nature of Carbonyl Cmpds:
Why are carboxylic acids better leaving groups than Aldehydes and ketones? |
They are able to stabilize a negative charge.
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Oxidation of Aldehydes:
What is the most common agent to convert aldehydes into carboxylic acids? |
CrO3
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What do you get?
Aldehyde (NaBH4)--> |
Alcohol
C-C-OH |
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What do you get?
Ketone (NaBH4)--> |
Prop-2-al
C-OH-C all single bonds, C bonded to an O which is bonded to the H and the C making an alcohol |
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What do you get?
Aldehyde (RMgX/H3O+)--> |
an secondary alcohol
OH C-C-H C |
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Nucleophilic Addition Reactions:
The alkoxide ion is protonated by? |
H-A
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Nucleophilic Addition Reactions:
What is the alkoxide ion |
it is the intermediate under Basic conditions
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Nucleophilic Add of Hydride and Grignard Reagents: Alcohol formation
Aldehydes with NaBH4 make a? Ketones with NaBH4 makes a? |
primary alcohol
secondary alcohol |
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Synthesis of Alcohols from Carbonyl cmpds:
Reduction of Aldehydes and Ketones: NaBH4 and what solvent is used? |
H3O+
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Nucleophilic Additon of Hydride & Grgnard Rxn: Alcohol Formation
Addition of Hydride (H-) Reagent: Reduction NaBH4 and what solvent is used? |
Ethanol H-O-R
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