Exam 2 Flashcards

1
Q

What is an alkane?

A

It is a saturated hydrocarbon (molecule with hydrogens and carbons)

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2
Q

What does saturated mean? Unsaturated?

A

Saturated means that there are as many hydrogens as possible. Unsaturated means that there are double or triple bonds

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3
Q

What is a homolog?

A

Compounds that only differ in the number of CH2 groups (root name)
methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane

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4
Q

What is the IUPAC naming for alkanes?

A

1) Find main chain (longest chain)
2) Number main chain from side with closes substituent
3) Name substituents as alkyl groups and give location (2-methyl not methane)
4) When 2+ alkyl groups put together alphabetically and when 2+ same alkyl groups combine numbers with commas and use di, tri, tetra, penta, hexa, hepta, octa, nona, deca, (2,2-dimethyl)

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5
Q

What about when two chains are the longest?

A

The chain with the most substituents wins

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6
Q

What are the rules for commas and dashes?

A

Numbers are separated by commas numbers and words separated by dashes

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7
Q

What are the common group names?

A

Isoalkyl
n-alkyl (normal don’t need to use n)
sec-alkyl (R group attaches to second)
tert-butyl (three carbons attached to central C)
R-CH3: Primary Carbon 1*
R-CH2-R: Secondary Carbon 2*
R-CH-R-R: Tertiary Carbon 3*
R-R-C-R-R Quatinary C 4*

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8
Q

What is the complex naming of subsituents?

A

1) Find Main Chain
2) Number chain starting with C attached to backbone
3) Everything else the same

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9
Q

What are the rules for cyclo compounds?

A

Root: either longest chain or biggest ring (whichever more C)
Don’t include ring in chain
Numbering the ring: start with two substituent over one, then start w/ alphabetically first, then go around to closest substituent

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10
Q

What prefixes count for alphabetical? Which don’t and why?

A

Count: Iso and cyclo
Don’t: sec-, turt-, cis-, trans- because has to do with spacial orientation

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11
Q

How does the root name change from alkanes to alkenes or alkynes?

A

Alkene: change to location-howmanyene
Alkyne: change to location-howmanyyne
Both: change to location-howmanyen-location-howmanyyne
Location = X where ene/yne starts
howmany = di, tri, etc
hept-1,3,5-triene
cis-oct-2-en-4-yne

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12
Q

When can cis/trans be used?

A

With double bonds and cyclo groups

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13
Q

What are the parts of the name of alkenes/alkynes containing molecules?

A

1) Root
2) Suffix- establish this first as it dictates what the root is
3) Prefix- everything else falls in here

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14
Q

What are the rules of more complicated organic molecules?

A

1) Identify highest priority functional group this is the suffix -all other groups will be substituents and included in the prefix
2) Identify the longest chain that contains the highest priority functional group -drop e of root if suffice starts with a vowel -longest chain with more substituents wins
3) Ennumeration: Highest priority group gets lowest number possible
-if tie give earliest substituent lowest number possible, if still tie go to the second substituent
-if still tie give lowest number to the substituent that comes first in the alphabet
4) Alkenes / ynes root ending changes to -ene or -yne
5) Prefix: list all remaining substituents in alphabetical orders
prefix, root name, and suffix without spaces

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15
Q

What happens with a nitrile?

A

the Carbon in the nitrile is number 1 of the longest chain when it is the highest priority

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16
Q

What are the functional groups by priority?

A

Carboxylic acid, ester, amide, nitrile, aldehyde, ketone, alcohol, thiol, amine, alkene, alkyne, alkane, ether, halide

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17
Q

What is the suffix and prefix for carboxylic acid?

A

-oic acid and carboxy

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18
Q

What is the suffix and prefix for ester?

A

-oate and alkoxycarbonyl

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19
Q

What is the suffix and prefix for amide?

A

-amide and amido

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20
Q

What is the suffix and prefix for nitrile?

A

-nitrile and cyano

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21
Q

What is the suffix and prefix for aldehyde?

A

-al and formyl

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22
Q

What is the suffix and prefix for ketone?

A

-one and oxo

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23
Q

What is the suffix and prefix for alcohol?

A

-ol and hydroxy

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24
Q

What is the suffix and prefix for thiol (R-SH)?

A

-thiol and mercapto

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25
What is the suffix and prefix for amine?
-amine and amino
26
What is the suffix and prefix for alkene?
-ene and alkenyl
27
What is the suffix and prefix for alkyne?
-yne and alkynyl
28
What is the suffix and prefix for alkane?
-ane and alkyl
29
What is the suffix and prefix for ether?
There is no suffix and alkoxy
30
What is the suffix and prefix for halide?
no suffix and halo
31
What is the complex naming of nitrile exception?
You do not have to put "1" if the nitrile is the base group because the C will ALWAYS be 1 in this case.
32
How do you name bicyclos?
1) Count the carbons 2) Name it bicyclo[...]alkane (how ever many carbons) 3) Locate the **two** bridge head atoms (atoms where everything is connected) 4) Count how many carbons are needed to cross the bridge (always three numbers, if no carbons in between the answer is 0) List largest to smallest [#.#.#] bicyclo[2.2.1]heptane
33
How do you name spiro compounds?
1) Count the carbons 2) Name is spiro[...]alkane (however many carbons name) 3) Count # of carbons on each loop (not combining carbon) and list smallest to largest [#.#] spiro[2.5]octane
34
When may cis/trans be used (as of now)?
One double bond (cannot rotate) cis-but-2-ene, trans-but-2-ene Two comparable substituents on a ring cis-1,3-dimethyl cyclohexane *three substituents cannot be cis-trans*
35
What are the properties of methane?
Tetrahedral, sp3, 109.5* gas that burns in presence of oxygen
36
How is ethane different from methane?
Two carbons joined by a single bond that is rotatable begging the question what is the most stable form/
37
What is the most stable form of ethane?
When the hydrogens are not aligned giving the hydrogens more physical space
38
What model is used to look a sigma bond head on?
Newman projection: spokes are the front and the circle is the back
39
What is a confirmational analysis? What are the names of the stages?
A look at the energy for each 60* turn of a Newman Projection and plot eclipsed, total eclipsed: highest energy staggered: Gauche & anti - lowest energy (zigzag formation)
40
What is saw horse projection?
looking a the bond at an angle
41
What is the bond and stability of cyclopropane?
60*, not incredibly stable due to significant (109.5-60) angle strain and torsional strain (H's are head on) (angle + torsional = ring)
42
What is the angle and strain of cyclobromane?
88*, not 90* because skewed (bird) to relieve some torsional strain
43
What is the angle and strain of cyclopentane?
108* envelope shape, little strain
44
What is the angle and strain of cyclohexane?
109.5* chair (lower) and boat (higher) conformation, skewed boat in between.
45
What are the names of the orientations of groups that come off of a cyclohexane?
Axial: straight up/down Equatorial: out on side
46
Where do bulky groups tend to orientate on cyclohexane?
Equatorial orientation.
47
What compound must remain equatorial?
tert-butyl
48
What is a mechanism?
A step-by-step of how a reaction happens, that is, where the electrons are moving, bonds broken and formed, as described by arrows *single barbed arrow*
49
How can a cyclohexane model keep you from making a mirror mistake?
It can keep you from making the molecule's enantiomer
50
What is thermodynamics?
The study of energy changes that accompany chemical and physical transformations. Allows for the comparison of stability of reactants and products, which compounds favored by equilibrium
51
What is kinetics?
Study of reaction rates, determining which products are formed fastest. Helps to predict how rate will change if change reaction conditions.
52
What type of a mechanism is halogenation?
Free radical mechanism
53
What is a free radical?
An unpaired electron
54
What are the steps of a free radical mechanism? What must you remember for the exam?
Initiation, propagation, and termination -do not have to label steps -initiation, propagation (all steps to show propagation), and termination (one termination) must be drawn -MUST HAVE **ARROWS**
55
What happens to a mechanism when you add one chlorine or bromine?
Two propagation steps are added 1-2 3-6 etc
56
What happens in the initiation step?
Two radicals come from none. When light is applied a small fraction of bond between diatomic chlorine is broken leaving with two chlorine radicals. (Homolytic cleavage)
57
What is the difference between homolytic and heterolytic cleavage?
Homolytic cleavage, also called radical cleavage, forms free radicals Heterolytic cleavage, also called ionic cleavage, forms ions
58
What occurs in the propagation step?
Halogen radical finds easiest partner H creating alkyl radical that must cleave halogen bond the halogen radical feeds back, *propagates*, to first reaction *not finished into all products are made*
59
What occurs in the termination step?
radicals come together (or collision with side of glass causes impromptu reaction)
60
What is the focus of thermodynamics in organic chemistry?
State functions and spontaneity -Gibbs free energy must be negative for spontaneity AG = AH - TAS TAS soo small, essentially ignore AG ~~AH *enthalpy will give a good idea of what is going on*
61
What is the formula for change in enthalpy?
AH = sum of (bond dissociation energy of broken) - sum of (bond dissociation energy of formed)
62
What keeps spontaneous reactions from occuring?
Activation energy
63
How is the rate of reaction determined?
Experimentally
64
What is the transition state?
The highest point of energy, where bonds are being formed
65
What is in a reaction energy diagram?
Reactants, activation energy leading to transition state, intermediates and products
66
What must be included in an energy diagram?
Reactants, intermediates, products, change in enthalpy of each step and overall, activation energy of each step, transition state of each step (double dagger), rate determining step, and **axis labels**
67
What is important to remember about RDS?
IT is the highest point on graph, pay attention to energy level **with respect to starting materials**
68
What are the radical selectivity trends?
Most --> Resonance, tertiary, secondary, primary, Methyl --> least stable Lowest intermediate energy: higher stability
69
What is Hammond's Postulate?
Related species that are closer in energy are closer in structure.
70
How does Hammond's Postulate apply to exothermic reactions?
The transition states are closer in energy to reactants so it is easier for them to go back to reactants. This means that there will be more reactants and the reaction will be less selective. *this is why we do not use fluorine, it is too exothermic and does not distinguish between forms*
71
How does Hammond's Postulate apply to endothermic reactions?
The transition states are closer in energy to intermediates so it is easier for them to go forward to intermediates. This means that there will be less reactants and the reaction will be more selective. *this is why iodine does not work--it is too endothermic*
72
What are reactive intermediates?
Short-lived, "stable" species on way to products carbocation, radical, carbanion, carbean
73
What is a carbocation?
R3C+, sp2, electron poor so wants electron density through inductive effect
74
What is the inductive effect?
The ability to share electrons through sigma bonds. Gets helping hand from near by Carbons if electron poor C-C bonds are more electron rich than C-H bonds
75
What is the range of stability for carbocations?
H3C+ < RC+H2 <<< R2C+H < R3C+ < Resonance Never form H3C + or RCH2+ without resonance
76
What is a carbon radical?
R3C* electron poor because not full octet, sp2, -radical in p orbital -not as electron poor as carbocation so not as much stabilization needed (H3C*, RC*H2 possible)
77
What is the range of stability for carbon radicals?
H3C* < RC*H2 < R2C*H < R3C* < resonance
78
What about the central atom when there are radicals?
The central atom will never have the radical because there must always be a double bond
79
What is a carbanion?
R3C- sp3 generally but if resonance sp2 electron rich so does not want more C around it
80
What is the range of stability for carbanions?
**Opposite of carbocations and radicals except for resonance wins** R3C**- < R2C**-H < RC**-H2 < H3C**- < resonance