Term
What is the formula for an Alkane? |
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Definition
CnH2n+2 (they have the max possible number of hydrogen atoms attached to each carbon, only single sigma bonds) |
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Definition
1° the carbon is bonded to only one other carbon |
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Definition
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Definition
3° carbon bonded to 3 other carbons |
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Definition
4° carbon bonded to 4 other carbon atoms |
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Definition
= (# of sigma bonds + # of lone pairs of electrons) |
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Term
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Definition
(Number of Valence Electrons of an Atom) - (Number of actual Electrons around the Atom in dot structure) |
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Term
Define Oxidation and Reduction |
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Definition
Oxidation - (increase in oxidation state -4 to +4) loss of electon LEO loss of electron is oxidation
Reduction - (decrease in oxidation state 0 to -2) gain of electron GER gain of electron is reduction
LEO the lion says GER |
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Definition
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Definition
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Definition
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Definition
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Definition
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10 pre-fix in nomenclature |
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Definition
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Term
11 prefix in nomenclature |
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Definition
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Term
12 prefix in nomenclature |
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Definition
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Term
13 prefix in nomenclature |
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Definition
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Term
14 prefix in nomenclature |
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Definition
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Term
15 prefix in nomenclature |
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Definition
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Term
15 prefix in nomenclature |
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Definition
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Term
16 prefix in nomenclature |
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Definition
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Term
17 prefix in nomenclature |
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Definition
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Term
18 prefix in nomenclature |
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Definition
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Term
19 prefix in nomenclature |
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Definition
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Term
20 prefix in nomenclature |
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Definition
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Term
What if there are 2 or more parent chains or backbones with different numbers of substituents but the same number of carbons in the parent chain you could draw? |
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Definition
According to IUPAC choose the parent chain with the most substituents |
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Term
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Definition
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Term
Rules for naming hydrocarbons |
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Definition
I. Find the longest carbon chain and name it.
II. Number the chain to give the substituents the lowest number possible
III. Identify and number the substituents
IV. Arrange the substituents alphabetically
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Term
First point of difference rule |
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Definition
If you have a hydrocarbon with the same parent chain, you name all substituents, then find the first difference in the numbers after numbering them and choose the lowest one |
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Term
If first point of difference in #'s fails then... |
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Definition
you go to the alphabet rule |
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Term
if there is a tie in the # of carbons in a cyclo and a straight chain... |
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Definition
you name the cyclo the alkane and the straight chain the alkyl |
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Term
How do you figure out how many rings you have? |
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Definition
By IUPAC determine how many cuts you have to make to make a straight chain and no more rings |
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Term
What is a bridgehead carbon? |
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Definition
Carbons that merge to rings |
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Term
Formula for naming bicyclo compounds |
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Definition
bicyclo[x.y.z]alkane
x=number of carbons in the longest path excluding bridgehead carbons
y=number of carbons in the second longest path excluding bridgehead carbons
z=number of carbons in the shortest path excluding bridgehead carbons(between bridgehead carbons) |
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Term
Anti-staggered conformation |
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Definition
the ch3s are 180o apart, most stable, least potential energy |
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Term
Gauche-staggered conformation |
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Definition
the methyl groups or ch3s are 60 degrees apart |
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Term
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Definition
not superimposable on its mirror image. means hand in greek |
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Term
what is a chiral carbon/center/atom? |
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Definition
usually a sp3 tetrahedral carbon that is bonded to 4 different groups |
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Term
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Definition
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Term
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Definition
rectus, when you move clockwise from largest to smallest atom on a chiral molecule |
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Term
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Definition
(S) Sinister, counterclockwise when ordering largest to smallest atom in a chiral molecule |
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Term
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Definition
stereoisomers that are non-superimposable mirror images
greek for "opposite"
opposite configurations at all chirality centers |
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Term
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Definition
objects that are superimposable on their mirror image |
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Term
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Definition
[alpha]=alpha/c*l
[alpha]=specific rotation
alpha=observed rotation
c=concentration (g/mL)
l=path length/length of tube (dm) |
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Term
optical purity or enantiometric excess |
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Definition
%ee=(observed[alpha]/[alpha]of pure enantiomer)*100
alpha = optical activity? |
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Term
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Definition
stereoisomers that are nonsuperimposable non-mirror images. it has the same atoms, sames bonds, but not mirror image of each other
-opposite configurations at some chirality centers |
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Term
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Definition
compound that has 2 or more chirality centers but the whole molecule is achiral. It can be superimposed on its mirror image
The way to spot them is it has 2 chiral centers, but it has a line of symmetry |
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Term
Sn1 and Sn2 both like polar solvents, but which one likes protic and which one likes non-protic? |
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Definition
Sn1 likes protics and Sn2 likes non-protic because if Sn2 was in protic, the nucleophile would always join H and the reaction would occur |
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Term
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Definition
nucleus lover
-region of high electron density
-attracted to nuclei |
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Term
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Definition
electron lover
-region of low electron density
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Term
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Definition
regions of high electron density (N) to regions of low electron density (E) |
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Term
The 5 most important things to understand in Organic Chemistry (Schwartz Rule) |
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Definition
I. Valence electrons (formal charge, oxidation state, dot structures)
II. Knowing how electronegativity effects reactions
III. Understand Acid/Base theory
IV. Redox chemistry
V. nucleophiles/electrophiles |
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Term
If you have a halogen or an alkyl in your parent chain,... |
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Definition
just go with the lowest number |
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Term
What is the fastest alkyl halide classification SN1? |
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Definition
methyl<1o<2o<3o
tertiary is the most stable so it want to react to get to that point |
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Term
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Definition
your nucleophile is also your solvent |
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Term
What happens in a Sn1 halide reaction thinking in terms of stereochemistry |
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Definition
inversions > 50% of the time (if S goes to R)
retention of the same form < 50% (if S stays S) |
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Term
In sterochemistry what happens on a Sn2 reaction? |
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Definition
You only get inversion because the halogen is on the other side. It can only attack on one side |
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Term
Which classifications are most likely to perform Sn2 reaction? |
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Definition
methyl>1o>2o>3o
there is more steric hinderance with 3o |
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Term
What functions only as a nucleophile (strong nucleophile)? |
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Definition
Cl-, Br-, I-, SH-, RSH (polarizable - electrons are far from the nucleus) |
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Term
What functions as a base only? |
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Definition
H-, it is not very polarized because it is small |
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Term
What can function as a strong Nu or strong Base? |
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Definition
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Term
What functions as a weak Nu or weak base? |
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Definition
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Term
functional groups on opposite sides of the double bond |
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Definition
trans - latin
entgegen (E) - German "across" |
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Term
functional groups on the same side of the double bond |
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Definition
cis - latin "together"
(z) Zusamen - german for "together" |
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Term
what is another name for ethene? |
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Definition
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Term
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Definition
CnH2n alkenes are "unsaturated" they could have 2 more hydrogens |
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Term
What is the most stable substituted alkene? |
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Definition
mono<disubstituted<trisubstituted<tetrasubstituted |
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Term
What is another name for ethyne? |
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Definition
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Term
Triple bonds cause what configuration? |
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Definition
linear, always draw them linear in a diagram |
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Term
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Definition
soluble in any proportion in water |
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Term
What happens to the boiling point as the R-chain gets longer in an alcohol? Why? |
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Definition
The boiling point goes up, because the london dispersion forces increase in longer chains. |
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Term
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Definition
miscible, lower boiling point |
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Term
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Definition
soluable but not miscible in water, higher boiling point than methanol |
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Term
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Definition
a benzene ring with a hydroxyl group |
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Term
What happens when you oxidize primary alcohol? |
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Definition
you must have alpha-hydrogens(hydrogens attached to the alpha carbon)
If you oxidize a primary alcohol 1 time you will get an aldehyde
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Term
What is another way to think about oxidizing? |
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Definition
increasing the C to O bonds, this is because O is more electronegative so it grabs those electrons from the C. |
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Term
What happens when you oxidize a secondary alcohol? |
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Definition
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Term
What happens when you oxidize a tertiary alcohol? |
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Definition
in theory you can't because you must have alpha hydrogen attached to the alpha carbon.
The result is NR no reaction |
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Term
What is the "jones reagent"? |
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Definition
Sodium Dichromate (Na2Cr2O7)
Sulfiric Acid (H2SO4)
Water (H2O)
this mixes together to form chromic acid which is used to oxidize alcohols
you can also use CrO3/H3O+/acetone |
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Term
Is dimethyl ether liquid or gas a room temp? |
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Definition
It is a gas, the boiling point is -25o it doesn't have hydrogen bonding in its intermolecular forces |
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Term
What happens to the boiling points of ethers as the carbon chains increase? |
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Definition
They go up because the dipole dipole moments increase, london dispersion forces |
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Term
How do you name aldehydes? |
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Definition
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Term
What are some common aldehydes? |
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Definition
formaldehyde - used to store dead things in (really strong smell)
benzaldehyde - (rosy smell)
cinnimaldehyde - (cinnamon smell)
acetaldehyde - (
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Term
Most basic Ketone, and how do you name ketones? |
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Definition
acetone (german for ketone)
write ketone at the end
or add "one" after the alkane |
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Term
what is the priority for naming functional groups? |
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Definition
Carboxylic Acids Acid Anhydrides Esters Acyl Halides Amides Nitriles Aldehydes Ketones Alcohols Thiols Amines Ethers Sulphides Alkenes Alkynes Alkyl Halides Nitro Alkanes |
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Term
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Definition
has an H on one side of the carbonyl and OH on the other |
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Term
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Definition
two carbonyls attached to each other with two OH's |
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Term
How do you name caboxylic acids? |
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Definition
add "oic acid" to the end of the alkane ex: butanoic acid
this will be at the beginning or end of the chain |
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Term
How do you name an amine? |
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Definition
add amine to the end "cyclohexanamine"
if it's not highest priority, use "amino" |
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Term
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Definition
NH2 connected to a benzene ring |
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Term
What is conjugation in Ochem? |
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Definition
alternating double and single bonds |
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Term
What is an allylic carbocation? |
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Definition
A carbocation that can be more stableized through a resonance structure |
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Term
How do you control a conjugated diene addition reaction? |
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Definition
By temperature, the 1,2 adduct happens faster, therefore at lower temperatures it is kinetically controlled. the 1, 4 happens slower, therefore, with more energy and higher temp it is the product |
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Term
what is a concerted mechanism? |
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Definition
all the transfers and leaving happens at the same time |
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Term
what do endo and exo mean in stereochemistry? |
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Definition
you compare the stereochemistry of the substituents. If the other bridge goes down to form a box, look if the OH is in or out of the box |
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Term
What is the Diels-Alder reaction? |
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Definition
when you merge a dien and a dienophile to make a cyclic or bicyclic compound. When you start with a cis dienophile your products are cis too, when you start with trans your products are trans too |
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Term
What products are favored in for regiochemistry in diels-alder reactions? |
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Definition
para(subs across 1,4) and ortho(subs by each other 1,2) are favored
meta is not favored(1,3) |
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Term
What is an in-phase molecular orbital? |
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Definition
goes from two atomic orbitals to one molecular orbital and they share electron densities through a covalent bond. It is called "bonding MO" they are lower in energy than anti-bonding MO or out of phase |
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Term
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Definition
two atomic orbitals make 2 MOs and they are called "anti-bonding" they form a node and do not share electron density. So there is a + and a + repelling each other in the middle so they are high energy |
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Term
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Definition
highest occupied molecular orbital |
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Term
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Definition
lowest unoccupied molecular orbital |
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Term
What are the frontier orbitals? |
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Definition
the LUMO and HOMO, the highest energy occupied mo and the next mo up that is unoccupied |
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Term
What are complementary colors in the light spectrum? |
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Definition
If you combine them you get white light |
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Term
What happens when you increase the amount of conjugation in a molecule? |
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Definition
You decrease the amount of energy it takes to get to an antibonding MO and it increases the wavelength making it easier and easier to see a visible color |
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Term
Why does bleach take out the color? |
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Definition
it reacts with the highly conjugated molecule and makes it less conjugated because it stops the sequence. Therefore the molecule doesn't absorb as high a wavelength so a visible color can't be seen. |
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Term
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Definition
a benzene ring with a methyl group attached
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Term
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Definition
a benzene ring with a carboxilic acid attached |
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Term
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Definition
a benzene ring with an aldehyde group
it has the smell of almonds |
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Term
what if the benzene ring is coming of as a substituent(the straight carbon chain is longer)? |
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Definition
you use "phenyl" it is a phenyl group |
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Term
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Definition
a benzene ring with a monosubstituted alkene |
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Term
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Definition
a benzene ring with and ether |
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Term
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Definition
a benzene ring with a ketone |
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Term
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Definition
a benzene ring with 2 methyl groups coming off of it |
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Term
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Definition
a benzene ring with an aldehyde, alcohol, and ether substituent |
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Term
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Definition
benzene ring with a methyl, and three nitro groups (2,4,6-trinitrotoluene) |
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Term
a compound is aromatic if... |
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Definition
I. contains a ring of constinuously overlapping p orbitals (planar)
II. has 4n+2 (huckel's rule) pi electrons in the ring, where n = 0,1,2...or any other positive integer |
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Term
What do 2 unpaired electrons imply? |
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Definition
instability and very reactive |
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Term
what does anti-aromatic mean? |
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Definition
a compound that fulfills the first rule but not the second of aromatic compounds |
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Term
What is an electrophilic aromatic substitution? |
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Definition
you have a electrophile and the double bond acts as a nucleophile. Then it gets deprotinated |
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Term
Why are the para and ortho formed with with a methoxy group in the benzene ring when you do a electrophile aromatic substitution reaction? |
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Definition
the methoxy group allows it to have 4 reasonance structures rather than just 3 in the ortho and para attack. It has a more stable sigma complex |
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Term
|
Definition
and electron donating group with increases electron density in a benzene ring |
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|
Term
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Definition
EWG - electron withdrawing group, decreases electron density in the benzene ring |
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Term
Why is the meta preferred when there is a nitro group attached to the benzene ring? |
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Definition
because there is a resonance structure in ortho and para that is not stable the N and C are both positive, it is a destablizing reasonance structure |
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Term
How do you quickly find a meta director? |
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Definition
see if the substituent has a + or partial + charge, then it is meta |
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Term
What is a stronger activator OH or a methyl group? |
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Definition
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|
Term
What are the steps in the Birch reduction reaction? |
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Definition
1. Na or another donates an electron.
2. the anion picks up a proton H
3. Na donates electrons
4. the anion picks up a proton H |
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Term
what are the requirements for nucleophilic aromatic substitution? |
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Definition
1. The ring has an electron withdrawing group
2. The ring has a leaving group
3. The leaving group is ortho or para to the EWG |
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Term
If p orbitals are in the same energy level, they are called? |
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Definition
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Term
what is the general rule for determining ionic and covalent bonding in terms of electronegativity differences? |
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Definition
0 = purely covalent
between 0-2 polar covalent
greater than 2 is ionic |
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Term
How many bonds does a nuetral carbon form? |
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Definition
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Term
How many bonds and lone pairs does a nuetral Nitrogen form? |
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Definition
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Term
How many bonds and lone pairs does a nuetral Oxygen form? |
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Definition
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Term
How many bonds and lone pairs does a nuetral X or halogens form? |
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Definition
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Term
What are the 3 rules for resonance structures? |
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Definition
1. Atoms are fixed and cannot move, only electrons can move
2. Only lone-pair electrons and pi electrons - which are only found in double or triple bonds - can move
3. You can't break the octet rule, the sum of bonds and lone pairs can't be more than 4 |
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Term
What four patterns are indicative of resonance structures? |
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Definition
1. lone pair next to double or triple bond
2. a cation next to a double bond, triple bond, or lone-pair of electrons
3. a double or triple bond containing an electronegative atom (acetone)
4. Alternating double bonds around a ring (benzene) |
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Term
How do you assign importance to resonance structures? |
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Definition
the more stable structures contribute more to the hybrid than unstable
3 factors determine stability
1. Fewest charges
2. Charges on the best atoms (positive charges on C(electropositive elements) and negative charges on electronegative elements (O and N))
3. Filled octets (generally, a full octet trumps charges on best atoms)
4. also, if the - + charges are farther apart in the compound they are less stable and higher energy, (ozone resonances are more stable than formic acids) |
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Term
what are the 4 most common mistakes in drawing resonance structures? |
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Definition
1. forgetting charges (net charges must be equal)
2. Breaking the octet rule (never draw 5 bonds on C)
3. moving single bonds
4. not following the electron flow (always draw them flowing in a single direction) |
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Term
What is an arrhenius acid? |
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Definition
molecules that dissociate in water to make the hydronium in H3O+
strong acids completely dissociate in water to form H3O+
acids that partially dissociate are weak |
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Term
what is a arrhenius base? |
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Definition
molecules that dissociate in water to make hydroxide ions OH-
strong bases completely dissociate in water to form OH-
bases that partially dissociate are weak |
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Term
Is a nucleophile an acid or base? |
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Definition
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Term
Can you be rigid in defining molecules as acids and bases? |
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Definition
you have to be careful because they are relative to whatever is thrown into the solution. They are relative to water. Sometimes an acid can be a base as with nitric and sulfiric acid. nitric can be a base |
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Term
How do you compare acidities of molecules? |
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Definition
strong acids have stable conjugate bases. The conjugate base has to delocalize the - charge as it is an anion.
The three most important features that stabilize negative charges include electronegativity, hybridization, and size of the atom upon which the negative charge is located, the electron-withdrawing effects of neighboring electronegative atoms, and resonance effects. |
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Term
What is more acidic?
R--OH,
R--CH3,
R--NH2 |
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Definition
R--OH > R--NH2 > R--CH3
the more electronegative elements prefer to have a negative charge on them so they are more stable. |
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Term
Order by acidity...
HF
HI
HCl |
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Definition
HI > HCl > HF
the larger the atom the more it can delocalize the negative charge. (more football stadiums to jump around to)
atom size trumps electronegativity |
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Term
Order by acidity... assume the orbital the lone pair resides on the following hybridized orbitals
sp2
sp3
sp |
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Definition
sp > sp2 > sp3
lone pairs prefer more "s" like character than "p" because "s" are closer to the nucleus and they want to be closer to the nucleus |
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Term
What if there are electronegative atoms on the acid, will it be more or less acidic? |
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Definition
More acidic because they pull they delocalize the (-) charge in the conjugate base (they act as EWG) |
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|
Term
What do resonance structures do to stability or acidity?
acetic acid
ethanol |
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Definition
resonance structures are a stabilizing feature of molecules, therefore the more resonance structures the conjugate base has, the more acidic it is.
acetic acid has a resonance structure |
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|
Term
how do you determine the equilibrium from the pKa? |
|
Definition
the lower the pKa the more acidic, the equillibrium arrow goes towards the higher pKa or weaker acid |
|
|
Term
What is ethylene(ethene)? |
|
Definition
a gaseous plant hormone that is released when the plant reaches maturity. Sometimes farmers will spray it when they want to force harvest. |
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|
Term
|
Definition
many ethylenes combined, plastic used in grocery bags, milk bottles, and other plastics |
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|
Term
Why are alkenes very useful? |
|
Definition
they are versatile, they can be used to synthesize many other functional groups |
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|
Term
Name one very important alkene. |
|
Definition
Vitamin A(retinol)
has 5 double bonds
important in vision, protects against sickness, and is used in skin care as an antioxidant |
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|
Term
Tell me interesting things about alkynes |
|
Definition
acetylene the most basic alkyne is a gas that is used in welding fuel because it burns cleanly and very hot 3000o C
They are less common than alkenes in nature.
they just found one made from bacterium that grows in rocks that fights cancer
They have 180o making them linear and not stable to form rings with less than eight carbons |
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|
Term
Where do we see aromatics in everyday life? |
|
Definition
lots of smells(aromas)
Morphine
auto exhaust
soot
tabacco smoke
many chimney sweeps got cancer from the carcinogens in the soot chemicals, some aromatics are harmful when burned |
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|
Term
Where do we see halides in everyday life? |
|
Definition
they aren't common in nature
they are often in compounds that are toxins
propellants, hairspray, spray paint, refridgerants, insecticides, teflon(contains fluorine)
good to synthesize |
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|
Term
Where do we find alcohols in everyday life? |
|
Definition
beer and wine (ethanol)
rubbing alcohol (isopropanol)
anti-freeze (ethylene glycol)
also sugars contain alcohol groups |
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|
Term
where do we see thiols in everyday life? |
|
Definition
they are stinky (R-SH)
in skunk spray, garlic, sewage, and rotten eggs
they add small amounts to methane gas commercially so you can know when the gas lines have sprung a leak
Cisteine, an amino acid important for protien production and keratin in hair
perms (you put chemicals in your hair with heat that breaks the disulfide bonds and then reforms them to stay in a different shape) |
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|
Term
Tell me interesting things about ethers... |
|
Definition
they are widely used as solvents in chemical reactions
back in the day they used diethyl ether to knock patients unconscious, it was painful to wake up though
ethers found in a ring are epoxides and are used in glues |
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|
Term
where do we see carboxylic acids in everyday life? |
|
Definition
they are abundant in nature
amino acids contain carboxylic acids
acetic acid or vinegar |
|
|
Term
|
Definition
made from carboxylic acids
very sweet smelling
many of the fruit smells, found in deoderants and artificial flavorings of food
end with the suffix -oate |
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|
Term
where do we see amides in everyday life? |
|
Definition
they are quite often found in nature
amide bonds hold all of our proteins together(amide bonds in proteins are called peptide bonds)
penicillin contains two amide groups |
|
|
Term
where do we see amines in everyday life? |
|
Definition
smell of decaying animals
nicotine and most of the illegal drugs are amine-containing compounds
R-NH2 or R2NH or R3N |
|
|
Term
|
Definition
compounds that contain C triply bonded to N
suffix - nitrile
"cyano" groups - as a substituent |
|
|
Term
How do you draw an sp3 hybridized carbon? |
|
Definition
two bonds in the plane of the page, one bond coming out of the page, and one bond going behind |
|
|
Term
What is a constitutional isomer? |
|
Definition
molecules with the same molecular formula, but with atoms connected to each other in different ways |
|
|
Term
|
Definition
same molecular forumla, same atom connectivity but with different orientations of those atoms in space |
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|
Term
What physical properties do enantiomers share? |
|
Definition
almost all, boiling, melting, dipole moments.
but they don't rotate plane-polarized light the same way, they rotate it in opposite directions |
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Term
What type of molecules rotate plane-polarized light? |
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Definition
only chiral molecules
enantiomers rotate plane-polarized light in equal and opposite directions |
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Term
What is a racemic mixture? |
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Definition
it occurs when you mix two enantiomers in equal proportions. They do not rotate plane-polarized light because half rotates it one way and the other half rotates it the opposite way.
These mixtures are optically inactive the net rotation is 0 |
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Term
What is the relationship between chiral centers and stereoisomers? |
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Definition
2n where n = the number of chiral centers. If you have 5 chiral centers there are 32 possible steroismoers. You typically don't have diastereomers unless you have more than 1 chiral centers. |
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Term
What are the rules for fischer projections? |
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Definition
1. you can rotate it 180o and retain the stereochemical configuration, but you can't rotate it 90o
2. You can rotate any three substituents on a fischer projection while holding one substituent fixed and retain the stereochemical configuration. |
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Term
How do you put complex substituents into the name? |
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Definition
put them in parantheses 5-(1,2-dimethylpropyl)-nonane |
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Term
What do ring flips do to a cyclohexane? |
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Definition
ring flips change all axial positions to equatorial and all equitorial positions to axial |
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Term
What conformation do the large groups or substituents prefer? |
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Definition
they prefer equitorial because they there is less strain. has no 1,3-diaxial strain
don't confuse conformation with configuration.
you don't change the configuration with a ring flip. They only way to change the configurations is by a chemical reaction |
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Term
Draw a chair conformation
now a flipped one |
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Definition
with the normal, you start 1 up
with flipped start 1 down |
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Term
if you have 2 substituents coming off a cyclohexane and are asked to draw the most stable chair conformation and they say it is trans, what do you do? |
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Definition
put the biggest group on equitorial and smallest on axial. |
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Term
Draw the haworth project... |
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Definition
draw a squashed cyclohexane, draw lines up and down from each carbon, number 1-6, a goes down on 1 and e goes up, alternate on every carbon. |
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Term
what reactions will you see from alkanes? why? |
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Definition
free-radical halogenation.
because they are essentially inert under most conditions. |
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Term
What are the 3 stages of chlorination? |
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Definition
chlorination is a photochemical, instead of using heat to start it, it uses light.
1. initiation - light is shown and observed by the Cl2, it breaks the bond to form 2 Cl radicals
2. propagation - the Cl radical plucks a hydrogen atom off the CH4 this make HCl plus a methyl radical. The methyl radical attacks another molecule of chlorine to make chloromethane plus another chloride radical
3. termination - when radicals form to make stable molecules |
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Term
What is the difference between bromination and chlorination? |
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Definition
bromine is more selevtive when deciding between the hydrogens (level of substitution). Chlorination doesn't care as much. |
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Term
how do you determine the degrees of unsaturation? |
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Definition
when you have fewer H than it becomes unsaturated
1 double bond = 1 degree of unsaturation
1 triple bond = 2 degrees of unsaturation
1 ring = 1 degree of unsaturation
1 degree means 2 less H's |
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Term
what is the degree of unsaturation for C3H4? |
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Definition
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Term
What if you have atoms other than H and C, how do you determine degrees of unsaturation? |
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Definition
Halogens(F, Cl, Br, I) - add one hydrogen to the molecular formula for each halogen present
Nitrogen - subtract one hydrogen for each nitrogen present
Oxygen and Sulfur - ignore |
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Term
In which types of molecules can you have cis,trans stereochemistry? |
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Definition
only in rings and on double bonds. You can't on single bonds because they can freely rotate at normal temps |
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Term
What factor affect the stability of alkenes? |
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Definition
1. subsitution, the more non-hydrogen substituents that come off the double bond, the more stable the alkene is
2. Generally trans isomers of alkenes are more stable than cis (because of electron repulsion)
3. |
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Term
What are the 3 primary ways to form alkenes? |
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Definition
1. dehydrohalogenation
2. dehydration
3. Wittig reaction
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Term
What is hyperconjugation? |
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Definition
weak overlap that occurs between the empty p orbital on the carbocation and the sigma bond of the adjacent alkyl C-H bond or C-C bond |
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Term
What is the ranking of stabilization for carbocations? |
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Definition
primary cation < secondary cation - allylic < tertiary cation - benzylic cation |
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Term
What is the relationship between a strong base and a nucleophile? |
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Definition
generally strong bases are strong nucleophiles except when the strong base is really bulky, then its hard to attach the substrate or electrophile.
negatively charged are stronger nucleophiles than neutral molecules
larger molecule are more polarizable and better nucleophiles |
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Term
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Definition
solvents that contain O-H or or N-H bonds. alcohols, water, and amines. |
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Term
What are some good aprotic solvents for SN2 reactions? |
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Definition
DMSO(dimethyl sulfoxide) CH2Cl2(dichloromethane), and ethers(R-O-R) |
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Term
What are good leaving groups in a SN2 reaction? |
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Definition
weak bases which are typically the conjugate bases of strong acids.
halogens except for F
tosylate is the best leaving group |
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Term
What are terrible leaving groups that you will never see in an SN2 reaction? |
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Definition
strong bases
(OH-), (RO-), and (NH2-) |
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Term
What are good SN1 substrates? |
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Definition
substrates that can make stable carbocation intermediates.
Things that can stabilize are resonance and alkyl groups, tertiary are the most stable |
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Term
Why do SN1 reactions prefer protic solvents? |
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Definition
because a protic solvent helps stabilize the cation intermediate which lowers the activation energy for the rate determining step.
Think about leaving a job, if the situation after you leave is more stable, you are more likely to leave.
For example the O on the water can help stabilize the positively charged C |
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Term
What 2 reagents are widely used to reduce carbonyl compounds? |
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Definition
NaBH4 (sodium borohydride) - weaker reducing agent (popgun) - makes a primary alcohol from a aldehyde and a secondary alcohol from a ketone
LiAlH4 (lithium aluminum hydride - stronger reducing agent
(cannon) - makes a primary alcohol from a carboxylic acid and a primary alcohol from an ester
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Term
How do you make a grignard reagent? |
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Definition
add magnesium to an alkyl halide, it inserts itself between the C-X bond R---MgX(grignard reagent)
this can then be used to make alcohols |
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Term
What are the reagents for making an alcohol through the markovnikov and anti-markonvnikov approaches? |
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Definition
1. Hg(OAc)2
2. NaBH4
1. BH3 THF
2. H2O2 |
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Term
What is one of the best reagents to convert alcohols to alkenes? |
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Definition
phosphorous oxychloride (POCl3)
this causes dehydration |
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Term
How do you make an ether from an alcohol? |
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Definition
react the alcohol with Na sodium metal, this makes and alcoxide which is a strong nucleophile. This then reacts with an alkyl halide through the SN2 mechanism to form the ether |
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Term
What 2 reagents can oxidize alcohols? |
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Definition
PCC (pyridinium chlorochromate) - weaker than jones
turns primary alcohol to aldehyde
turns secondary alcohol to ketone
Jones Reagent (Na2Cr2O7 + H2SO4 + H2O)
turns primary alcohol to carboxylic acid because it is stronger
turns secondary alcohol to ketone
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Term
what happens when you add hydrohalic acids to conjugated alkenes? |
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Definition
you have a 1,2 addition at low temps because it is the kinetic product
you have a 1,4 addition at high temps because it is the thermodynamic product. It takes more energy but is more stable in the end
draw out a conjugated diene and add a hydrogen to the 1 spot |
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Term
what are good electron withdrawing groups for the dienophile in the Diels-Alder reaction? |
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Definition
CN (cyano groups), NO2 (Nitro groups), and all other carbonyl compounds |
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Term
what are good electron donating groups for the diene in the Diels-Alder reaction? |
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Definition
ethers (OR), alcohols (OH), and amines (NR2) |
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Term
What are MO molecular orbitals called? |
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Definition
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Term
What is
toluene?
aniline?
phenol?
anisole?
benzoic acid?
benzaldehyde?
styrene?
benzonitrile? |
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Definition
toluene? - benzene + methyl group
aniline? benzene + NH2
phenol? benzene + OH
anisole? benzene + OCH3
benzoic acid? benzene + COOH
benzaldehyde? benzene + CHO
styrene? benzene + CN
benzonitrile? benzene + CN |
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Term
where do electron-withdrawing groups direct substitution?
where do electron-donating groups direct substitution? |
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Definition
1. meta
2. ortha and para
because the cations have more resonance structures |
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Term
How do you know what will be a para, ortho, or meta director? |
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Definition
any substituent whose first atom(the one attached to the benzene) contains a lone pair of electrons will be an ortho-para director (although not necessarily a ring activator). Those substituents without a lone pair on the first atom will likely be meta directors (with the exception of alkyl groups and aromatic rings, which are ortho-para directors) |
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