Shared Flashcard Set

Details

Organic Chemistry
Organic Chemistry
208
Chemistry
Undergraduate 3
01/30/2014

Additional Chemistry Flashcards

 


 

Cards

Term
What is the formula for an Alkane?
Definition
CnH2n+2 (they have the max possible number of hydrogen atoms attached to each carbon, only single sigma bonds)
Term
primary carbon atom
Definition
1° the carbon is bonded to only one other carbon
Term
secondary carbon
Definition
2° carbon is bonded to 2
Term
Tertiary carbon
Definition
3° carbon bonded to 3 other carbons
Term
Quaternary carbon
Definition
4° carbon bonded to 4 other carbon atoms
Term
Steric Number SN =
Definition
= (# of sigma bonds + # of lone pairs of electrons)
Term
What is formal charge?
Definition
(Number of Valence Electrons of an Atom) - (Number of actual Electrons around the Atom in dot structure)
Term
Define Oxidation and Reduction
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

Term
Bronsted-Lowry Acid
Definition
proton donor
Term
Bronsted-Lowry Base
Definition
proton acceptor
Term
Lewis Acid
Definition
electron pair acceptor
Term
Lewis Base
Definition
electron pair donor
Term
9 pre-fix in orgo
Definition
non
Term
10 pre-fix in nomenclature
Definition
dec
Term
11 prefix in nomenclature
Definition
undec
Term
12 prefix in nomenclature
Definition
dodec
Term
13 prefix in nomenclature
Definition
tridec
Term
14 prefix in nomenclature
Definition
tetradec
Term
15 prefix in nomenclature
Definition
pentadec
Term
15 prefix in nomenclature
Definition
pentadec
Term
16 prefix in nomenclature
Definition
hexadec
Term
17 prefix in nomenclature
Definition
heptadec
Term
18 prefix in nomenclature
Definition
octadec
Term
19 prefix in nomenclature
Definition
nonadec
Term
20 prefix in nomenclature
Definition
eicos
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?
Definition
According to IUPAC choose the parent chain with the most substituents
Term
formula for cycloalkane
Definition
CnH2n
Term
Rules for naming hydrocarbons
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

 

Term
First point of difference rule
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
Term
If first point of difference in #'s fails then...
Definition
you go to the alphabet rule
Term
if there is a tie in the # of carbons in a cyclo and a straight chain...
Definition
you name the cyclo the alkane and the straight chain the alkyl
Term
How do you figure out how many rings you have?
Definition
By IUPAC determine how many cuts you have to make to make a straight chain and no more rings
Term
What is a bridgehead carbon?
Definition
Carbons that merge to rings
Term
Formula for naming bicyclo compounds
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)

Term
Anti-staggered conformation
Definition
the ch3s are 180apart, most stable, least potential energy
Term
Gauche-staggered conformation
Definition
the methyl groups or ch3s are 60 degrees apart
Term
define chiral
Definition
not superimposable on its mirror image. means hand in greek
Term
what is a chiral carbon/center/atom?
Definition
usually a sp3 tetrahedral carbon that is bonded to 4 different groups
Term
stereochemistry
Definition
study of 3D chemistry
Term
right in latin
Definition
rectus, when you move clockwise from largest to smallest atom on a chiral molecule
Term
left in latin
Definition
(S) Sinister, counterclockwise when ordering largest to smallest atom in a chiral molecule
Term
Enantionmers
Definition

stereoisomers that are non-superimposable mirror images

greek for "opposite"

opposite configurations at all chirality centers
Term
achiral
Definition
objects that are superimposable on their mirror image
Term
Specific Rotation
Definition

[alpha]=alpha/c*l

 

[alpha]=specific rotation

alpha=observed rotation

c=concentration (g/mL)

l=path length/length of tube (dm)

Term
optical purity or enantiometric excess
Definition

%ee=(observed[alpha]/[alpha]of pure enantiomer)*100

 

alpha = optical activity?

Term
diastereomers
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

Term
mesocompound
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

Term
Sn1 and Sn2 both like polar solvents, but which one likes protic and which one likes non-protic?
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
Term
nucleophile
Definition

nucleus lover

-region of high electron density

-attracted to nuclei

Term
electrophile
Definition

electron lover

-region of low electron density

 

 

Term
Electrons flow from...
Definition
regions of high electron density (N) to regions of low electron density (E)
Term
The 5 most important things to understand in Organic Chemistry (Schwartz Rule)
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

Term
If you have a halogen or an alkyl in your parent chain,...
Definition
just go with the lowest number
Term
What is the fastest alkyl halide classification SN1?
Definition

methyl<1o<2o<3o

 

tertiary is the most stable so it want to react to get to that point

Term
Solvolysis
Definition
your nucleophile is also your solvent
Term
What happens in a Sn1 halide reaction thinking in terms of stereochemistry
Definition

inversions > 50% of the time (if S goes to R)

retention of the same form < 50% (if S stays S)

Term
In sterochemistry what happens on a Sn2 reaction?
Definition
You only get inversion because the halogen is on the other side. It can only attack on one side
Term
Which classifications are most likely to perform Sn2 reaction?
Definition

methyl>1o>2o>3o

 

there is more steric hinderance with 3o

Term
What functions only as a nucleophile (strong nucleophile)?
Definition
Cl-, Br-, I-, SH-, RSH (polarizable - electrons are far from the nucleus)
Term
What functions as a base only?
Definition
H-, it is not very polarized because it is small
Term
What can function as a strong Nu or strong Base?
Definition
RO-, or OH-
Term
What functions as a weak Nu or weak base?
Definition
ROH or H2O
Term
functional groups on opposite sides of the double bond
Definition

trans - latin

entgegen (E) - German "across"

Term
functional groups on the same side of the double bond
Definition

cis - latin "together"

(z) Zusamen - german for "together"
 

Term
what is another name for ethene?
Definition
Ethylene
Term
general alkene formula?
Definition
CnH2n alkenes are "unsaturated" they could have 2 more hydrogens
Term
What is the most stable substituted alkene?
Definition
mono<disubstituted<trisubstituted<tetrasubstituted
Term
What is another name for ethyne?
Definition
acetylene
Term
Triple bonds cause what configuration?
Definition
linear, always draw them linear in a diagram
Term
define miscible
Definition
soluble in any proportion in water
Term
What happens to the boiling point as the R-chain gets longer in an alcohol? Why?
Definition
The boiling point goes up, because the london dispersion forces increase in longer chains.
Term
Methanol properties
Definition
miscible, lower boiling point
Term
butanol properties
Definition
soluable but not miscible in water, higher boiling point than methanol
Term
what is phenol?
Definition
a benzene ring with a hydroxyl group
Term
What happens when you oxidize primary alcohol?
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

 

Term
What is another way to think about oxidizing?
Definition
increasing the C to O bonds, this is because O is more electronegative so it grabs those electrons from the C.
Term
What happens when you oxidize a secondary alcohol?
Definition
you get a ketone
Term
What happens when you oxidize a tertiary alcohol?
Definition

in theory you can't because you must have alpha hydrogen attached to the alpha carbon.

The result is NR no reaction

Term
What is the "jones reagent"?
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

Term
Is dimethyl ether liquid or gas a room temp?
Definition
It is a gas, the boiling point is -25it doesn't have hydrogen bonding in its intermolecular forces
Term
What happens to the boiling points of ethers as the carbon chains increase?
Definition
They go up because the dipole dipole moments increase, london dispersion forces
Term
How do you name aldehydes?
Definition
add "al" to the alkane
Term
What are some common aldehydes?
Definition

formaldehyde - used to store dead things in (really strong smell)

benzaldehyde - (rosy smell)

cinnimaldehyde - (cinnamon smell)

acetaldehyde - (

 

Term
Most basic Ketone, and how do you name ketones?
Definition

acetone (german for ketone)

write ketone at the end

or add "one" after the alkane

Term
what is the priority for naming functional groups?
Definition
Carboxylic Acids 
Acid Anhydrides 
Esters 
Acyl Halides 
Amides 
Nitriles 
Aldehydes 
Ketones 
Alcohols 
Thiols 
Amines 
Ethers 
Sulphides 
Alkenes 
Alkynes 
Alkyl Halides 
Nitro 
Alkanes 
Term
what is formic acid?
Definition
has an H on one side of the carbonyl and OH on the other
Term
what is oxalic acid
Definition
two carbonyls attached to each other with two OH's
Term
How do you name caboxylic acids?
Definition

add "oic acid" to the end of the alkane ex: butanoic acid

this will be at the beginning or end of the chain

Term
How do you name an amine?
Definition

add amine to the end "cyclohexanamine"

 

if it's not highest priority, use "amino"

Term
What is aniline?
Definition
NH2 connected to a benzene ring
Term
What is conjugation in Ochem?
Definition
alternating double and single bonds
Term
What is an allylic carbocation?
Definition
A carbocation that can be more stableized through a resonance structure
Term
How do you control a conjugated diene addition reaction?
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
Term
what is a concerted mechanism?
Definition
all the transfers and leaving happens at the same time
Term
what do endo and exo mean in stereochemistry?
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
Term
What is the Diels-Alder reaction?
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
Term
What products are favored in for regiochemistry in diels-alder reactions?
Definition

para(subs across 1,4) and ortho(subs by each other 1,2) are favored

 

meta is not favored(1,3)

Term
What is an in-phase molecular orbital?
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
Term
What is out of phase MO?
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
Term
what is HOMO?
Definition
highest occupied molecular orbital
Term
What is LUMO?
Definition
lowest unoccupied molecular orbital
Term
What are the frontier orbitals?
Definition
the LUMO and HOMO, the highest energy occupied mo and the next mo up that is unoccupied
Term
What are complementary colors in the light spectrum?
Definition
If you combine them you get white light
Term
What happens when you increase the amount of conjugation in a molecule?
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
Term
Why does bleach take out the color?
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.
Term
what is toluene?
Definition

a benzene ring with a methyl group attached

 

Term
what is benzoic acid?
Definition
a benzene ring with a carboxilic acid attached
Term
what is benzaldehyde?
Definition

a benzene ring with an aldehyde group

it has the smell of almonds

Term
what if the benzene ring is coming of as a substituent(the straight carbon chain is longer)?
Definition
you use "phenyl" it is a phenyl group
Term
What is styrene?
Definition
a benzene ring with a monosubstituted alkene
Term
what is anisole?
Definition
a benzene ring with and ether
Term
what is acetophenone?
Definition
a benzene ring with a ketone
Term
What is xylene?
Definition
a benzene ring with 2 methyl groups coming off of it
Term
what is vanillin?
Definition
a benzene ring with an aldehyde, alcohol, and ether substituent
Term
what is TNT?
Definition
benzene ring with a methyl, and three nitro groups (2,4,6-trinitrotoluene)
Term
a compound is aromatic if...
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

Term
What do 2 unpaired electrons imply?
Definition
instability and very reactive
Term
what does anti-aromatic mean?
Definition
a compound that fulfills the first rule but not the second of aromatic compounds
Term
What is an electrophilic aromatic substitution?
Definition
you have a electrophile and the double bond acts as a nucleophile. Then it gets deprotinated
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?
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
Term
what is an activator?
Definition
and electron donating group with increases electron density in a benzene ring
Term
what is a deactivator?
Definition
EWG - electron withdrawing group, decreases electron density in the benzene ring
Term
Why is the meta preferred when there is a nitro group attached to the benzene ring?
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
Term
How do you quickly find a meta director?
Definition
see if the substituent has a + or partial + charge, then it is meta
Term
What is a stronger activator OH or a methyl group?
Definition
OH
Term
What are the steps in the Birch reduction reaction?
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

Term
what are the requirements for nucleophilic aromatic substitution?
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

Term
If p orbitals are in the same energy level, they are called?
Definition
degenerate orbitals
Term
what is the general rule for determining ionic and covalent bonding in terms of electronegativity differences?
Definition

0 = purely covalent

between 0-2 polar covalent

greater than 2 is ionic

Term
How many bonds does a nuetral carbon form?
Definition
4, with no lone pairs
Term
How many bonds and lone pairs does a nuetral Nitrogen form?
Definition
3 bonds, 1 lone pair
Term
How many bonds and lone pairs does a nuetral Oxygen form?
Definition
two bonds, 2 lone pairs
Term
How many bonds and lone pairs does a nuetral X or halogens form?
Definition
one bond, 3 lone pairs
Term
What are the 3 rules for resonance structures?
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

Term
What four patterns are indicative of resonance structures?
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)

Term
How do you assign importance to resonance structures?
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)

Term
what are the 4 most common mistakes in drawing resonance structures?
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)

Term
What is an arrhenius acid?
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

Term
what is a arrhenius base?
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

Term
Is a nucleophile an acid or base?
Definition
Lewis base
Term
Can you be rigid in defining molecules as acids and bases?
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
Term
How do you compare acidities of molecules?
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.

Term

What is more acidic?

 

R--OH,

R--CH3,

R--NH2

Definition

R--OH > R--NH2 > R--CH3

 

the more electronegative elements prefer to have a negative charge on them so they are more stable.

Term

Order by acidity...

 

HF

HI

HCl

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

Term

Order by acidity... assume the orbital the lone pair resides on the following hybridized orbitals

 

sp2

 

sp3

 

sp

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

Term
What if there are electronegative atoms on the acid, will it be more or less acidic?
Definition
More acidic because they pull they delocalize the (-) charge in the conjugate base (they act as EWG)
Term

What do resonance structures do to stability or acidity?

 

acetic acid

 

ethanol

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

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.
Term
what is polyethylene?
Definition
many ethylenes combined, plastic used in grocery bags, milk bottles, and other plastics
Term
Why are alkenes very useful?
Definition
they are versatile, they can be used to synthesize many other functional groups
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

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 3000C

 

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

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

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

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

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)

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

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
tell me about esters
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

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
what are nitriles?
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
What is a stereoisomer?
Definition
same molecular forumla, same atom connectivity but with different orientations of those atoms in space
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

Term
What type of molecules rotate plane-polarized light?
Definition

only chiral molecules

 

enantiomers rotate plane-polarized light in equal and opposite directions

Term
What is a racemic mixture?
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

Term
What is the relationship between chiral centers and stereoisomers?
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.
Term
What are the rules for fischer projections?
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.

Term
How do you put complex substituents into the name?
Definition
put them in parantheses 5-(1,2-dimethylpropyl)-nonane
Term
What do ring flips do to a cyclohexane?
Definition
ring flips change all axial positions to equatorial and all equitorial positions to axial
Term
What conformation do the large groups or substituents prefer?
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

Term

Draw a chair conformation

 

now a flipped one

Definition

with the normal, you start 1 up

 

with flipped start 1 down

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?
Definition
put the biggest group on equitorial and smallest on axial.
Term
Draw the haworth project...
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.
Term
what reactions will you see from alkanes? why?
Definition

free-radical halogenation.

 

because they are essentially inert under most conditions.

Term
What are the 3 stages of chlorination?
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

Term
What is the difference between bromination and chlorination?
Definition
bromine is more selevtive when deciding between the hydrogens (level of substitution). Chlorination doesn't care as much.
Term
how do you determine the degrees of unsaturation?
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

Term
what is the degree of unsaturation for C3H4?
Definition
2
Term
What if you have atoms other than H and C, how do you determine degrees of unsaturation?
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

Term
In which types of molecules can you have cis,trans stereochemistry?
Definition
only in rings and on double bonds. You can't on single bonds because they can freely rotate at normal temps
Term
What factor affect the stability of alkenes?
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.  

Term
What are the 3 primary ways to form alkenes?
Definition

1. dehydrohalogenation 

2. dehydration

3. Wittig reaction

 

Term
What is hyperconjugation?
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
Term
What is the ranking of stabilization for carbocations?
Definition
primary cation < secondary cation - allylic < tertiary cation - benzylic cation
Term
What is the relationship between a strong base and a nucleophile?
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

Term
What does protic mean?
Definition
solvents that contain O-H or or N-H bonds. alcohols, water, and amines.
Term
What are some good aprotic solvents for SN2 reactions?
Definition
DMSO(dimethyl sulfoxide) CH2Cl2(dichloromethane), and ethers(R-O-R)
Term
What are good leaving groups in a SN2 reaction?
Definition

weak bases which are typically the conjugate bases of strong acids. 

 

halogens except for F

 

tosylate is the best leaving group

Term
What are terrible leaving groups that you will never see in an SN2 reaction?
Definition

strong bases

 

(OH-), (RO-), and (NH2-)

Term
What are good SN1 substrates?
Definition

substrates that can make stable carbocation intermediates.

 

Things that can stabilize are resonance and alkyl groups, tertiary are the most stable 

Term
Why do SN1 reactions prefer protic solvents?
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

Term
What 2 reagents are widely used to reduce carbonyl compounds?
Definition

NaBH4 (sodium borohydride) - weaker reducing agent (popgun) - makes a primary alcohol from a aldehyde and a secondary alcohol from a ketone

 

LiAlH(lithium aluminum hydride - stronger reducing agent

(cannon) - makes a primary alcohol from a carboxylic acid and a primary alcohol from an ester

 

Term
How do you make a grignard reagent?
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

Term
What are the reagents for making an alcohol through the markovnikov and anti-markonvnikov approaches?
Definition

1. Hg(OAc)2

2. NaBH4

 

 

1. BH3 THF

2. H2O2

Term
What is one of the best reagents to convert alcohols to alkenes?
Definition

phosphorous oxychloride (POCl3)

 

this causes dehydration

Term
How do you make an ether from an alcohol?
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
Term
What 2 reagents can oxidize alcohols?
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

 

Term
what happens when you add hydrohalic acids to conjugated alkenes?
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

Term
what are good electron withdrawing groups for the dienophile in the Diels-Alder reaction?
Definition
CN (cyano groups), NO2  (Nitro groups), and all other carbonyl compounds
Term
what are good electron donating groups for the diene in the Diels-Alder reaction?
Definition
ethers (OR), alcohols (OH), and amines (NR2)
Term
What are MO molecular orbitals called?
Definition
psi, pronounced "sigh"
Term

What is 

 

toluene?

aniline?

phenol?

anisole?

benzoic acid?

benzaldehyde?

styrene?

benzonitrile?

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

Term

where do electron-withdrawing groups direct substitution?

 

where do electron-donating groups direct substitution?

Definition

1. meta

 

2. ortha and para

 

because the cations have more resonance structures

Term
How do you know what will be a para, ortho, or meta director?
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)
Supporting users have an ad free experience!