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Flashcards in Ochem 1 Deck (148):
1

Hydrazine 

N2H4

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2

Vinyl

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2

Define observed rotation of a molecule

  • What determines it?

degree to which a sample rotates PPL

  • determined by:
    • [ ]
    • length of tube, etc.

2

Why are alcohols soluble in water?

They can H bond with water

3

Cycloalkanes and ring strain 

  • How much ring strain do big, small, bicyclic & monocyclic cycloalkanes have? 

  1. Cycloalkanes w/ LESS than 6 C's have increasingly more ring strain
  2. Really BIG (10+) rings have enough freedom to approximate 109.5º
  3. BICYCLIC ring systems have MORE ring strain than MONOcyclic rings

4

If you see C6H5, what is it?

a BENZENE!

  • not a straight chain
  • since it has π bonds, it is unsaturated

4

1º,2º,3º OH groups have 1,2, and 3 ___ ___ which do what to charge?

What does this mean?

Have 1,2, and 3 donating groups to destabilize charge

this is why 3º is less acidic than 1º

5

Hückel's Rule (for aromaticity) 

to exhibit aromaticity

a ring must have EXACTLY __+__ electrons

 

to exhibit aromaticity

a ring must have EXACTLY: 4n+2π electrons

​From what I've gathered, "n" is just 1 (at least it is for benzene...( 4(1) + 2π= 6 )

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Hemiketal

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7

Physical properties of alkanes

  • Soluble/Insoluble in water?
  • Low/High density?
  • polar/non-polar?
  • What increases BP?
  • What decreases it?
  • What increases MP?

  • insoluble in water
  • very low density
  • non-polar
  • BP increases with increasing chain length and/or MW
  • BP decreases with increased branching (decreased symmetry)
  • MP increases with increasing chain length and/or MW

7

Cyclic rings create ___ ___ and make bond angles do what?

  • ring strain
  • make bond angles deviate from preferred 109.5º

7

Alkenes are _____s!

Why?

Nucleophiles!

  • π bonds are e' dense and will attach E:philes
    • forming a new bond to one of the C's
    • and leaving a CCI on the other
      • CCI then attacked by a Nu:

8

What does an SN2 rxn look like?

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9

Rank BOND REACTIVITY for:

  • Single bonds
  • Double bonds
  • Triple bonds

triple>double>single

more reactive bc of π bonds

 

10

3º ROHs can only be oxidized into ___?

PSYCHE!

They cant be oxidized at all!

11

1º ROH can be oxidized into?

1º ROH⇒Aldehydes⇒Carboxylic Acids

12

Alcohols are less/more acidic than water

  • Rank alcohol acidity 

LESS acidic than water

  • ROH acidity increases from: 
    • (most acidic) 1>2>3 (least acidic)

13

Imine

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14

Hybridization: 

sp3, 1 LP

Trigonal Planar

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15

Hybridization:

sp3d, 2 LPs

T-shaped

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16

What is a racemic mixture a mixture OF?

50/50 mix of R and S enantiomers

17

Anomers

  • If anomeric OH/OR group and CH2OH group are on opposite sides of the ring, what kind of anomer is it?

ALPHA anomer

on the "Alpha-site side"

18

Alcohols behave as either: ___s or as a ___

1) Nucleophiles

  • (the lone pair on oxygen acts as a Lewis base)

2) Lewis acids

  • ..when they are oxidized to carbonyl groups
    •  the oxygen ACCEPTS A PAIR OF ELECTRONS (Lewis Acid) from the O-H bond as the proton is abstracted

19

Hybridization: 

sp3d2, 1 LP

Square Pyramidal

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20

Are Alkyl substituents strong or weak e' donating groups?

weak

21

Absolute conformation (__ & __)how do you assign priority to 4 R groups?

Assign priority starting with:

HIGHEST MW

(heavier=higher priority, i.e. 4)

(lighter, like H=lower priority, i.e.1)

If 1-->3 is clockwise=R

If 1-->3 is counter clockwise =S

22

Gringard Synthesis:

Describe the 2 steps (using R-MgBr)

1) Mg has VERY LOW ELECTRONEGATIVITY

  • so the R group in R-MgBr attacks the electrophilic carbonyl C
  • Occurs in single step
    • kicking e's in C=O bond onto the oxygen

2) (-) charged oxygen is protonated

  • yielding an alcohol

23

What are diastereomers?

Have same MF & connectivity (like steroisomers)

are NON-identical, NON-superimposable

mirror images

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24

Amine

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25

Anhydride

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25

Benzyl

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25

Sulfone 

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25

Hybridization:

sp2, no LPs

Trigonal Planar

Ex: BF3

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25

HYbridization: 

sp3d, no LPs

Trigonal BIpyramidal

Ex: PF5

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25

Hybridization:

sp3d, 3 LPs

Linear

ex: XeF2

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25

Rank bond STABILITY for:

  • Single Bonds
  • Double Bonds
  • Triple Bonds

Explain what makes the least stable one the least stable

single>double>triple

  • Triple bond is LESS stable because it has 2 reactive π bonds!

 

25

RANKING resonance structures

  • ​You want MORE ____s, LESS _____
  • The most STABLE species has the most WHAT?

MORE bonds, LESS charges

The most stable species has the MOST POSSIBLE RESONANCE STRUCTURES

26

Describe the 2-step formation of: 

  • TOSYLATES / MESYLATES

 

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  1. ROH attacks X (via SN2)
    • kicks off X
  2. H is abstracted by X ion

 

Mesylates and Tosylates are desirable because they make very good LGs that will react readily with almost any nucleophile

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27

Define "LEVOROROTARY"

  • Using FISCHER PROJECTIONS, differentiate b/t D- Glyceraldehyde and L-Glyceraldehyde 

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compound rotates light

counter-clockwise (-)

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28

Acetyl

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28

2 molecules have the same RELATIVE CONFIGURATION if:

  • Their 3D arrangement is ___, but they have 1 (and ONLY 1) ___-____ _____

SAME RELATIVE CONFIGURATION if:

Their 3D arrangement is IDENTICAL, but they have 1 (and ONLY 1) NON-IDENTICAL SUBSTITUENT

29

Hybridization: 

sp3, no LPs

TETRAHEDRAL

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30

Structural/ Constitutional Isomers have the SAME____, but different _____

Same MF

BUT

Different connectivity

32

ETHERS, ROR', are excellent...?

Solvents!

33

2º ROHs can ONLY be oxidized into ___

Can they be oxidized any further, like 1° ROHs?

Ketones

Can NOT be further oxidized

34

What are the 2 types of reactions you'll

see ETHERS, ROR', used in? 

  1. Ethers will almost ALWAYS be the SOLVENT
    • ∴ wont participate in rxn
  2. If Ethers DO react, it'll only be after the O- is protonated by a strong acid (HCl)
    • resulting in a carbocation intermediate
    • which would then be attacked by a nucleophile

35

Nitrile 

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36

Ester

HINT: Ester drinks COORS

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37

What are a few common OXIDIZING AGENTS?

HINT: OKPeePee!

  • O3Cr2O7
  • KMnO4
  • PCC
  • PDC

38

List 4 characteristics of π bonds

  1. prevent rotation
  2. weaker than sigma bonds
  3. less stable
  4. more reactive

40

Aldehyde

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41

In DEHYDRATION of an ROH:

  • What is favored by a HOT, concentrated acid?
  • What is favored by a COLD, dilute acid?

In a dehydration reaction, what is the MAJOR product?

Alkene

  • is favored by a hot, concentrated acid

Alcohol

  • is favored by a cold, dilute acid

 

Major product is the more substituted

(more stable) alkene

42

Describe SN2 rxns

Rate depends on [ ] of 2 species

  • so its SECOND order
  • ONE step

STEP:

  • Backside attack of Nu:
    • w/ simultaneous ejection of LG

43

Carboxylic acid

COOH

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44

Alkyl group

Hydrocarbons ONLY!!!

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45

Define a "Base" in an ochem reaction

  • What do they do to protons?
  • Are they electron dense or deficient?
  • What kind of charge do they have?

ABSTRACT protons

  • are electron DENSE
  • have full or partial (-) charge

46

Dehydration of ROH: synthesis of an ___.this is an ___ rxn

alkeneis an equilibrium rxn

47

What are Meso cpds?Why dont they have optical activity?Are they diastereomers? Why/Why not?

  • -have 2+ chiral centers AND a plane of symmetry
  • POS cancels out optical activity
  • ARENT diastereomers, b/c diastereomers are PAIRS of cpds.
  • Meso cpds are single cpds with a POS-
    • Therefore, can't be diastereomers NOR enantiomers

48

Define "ALIPHATIC"

  • If something has a benzene ring, is it aliphatic or not?

Relating to organic compounds whose carbon atoms are linked in open chains

  • either straight or branched

rather than containing a benzene ring

Something is either ALIPHATIC or AROMATIC

Example:

Alkanes, alkenes, and alkynes are aliphatic compounds

 

 

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49

Enamine 

"Enamine" is derived from:

  • the affix en-
    • used as the suffix of alkene
  • the root amine

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50

Dehydration of an ROH:

  • Describe the 3 steps
  • What can occur during this reaction?
    • In what circumstance would it occur?

Steps:

  1. Protonation of alcohol
  2. Water (which is the LG here) leaves
    • CCI is formed
  3. H2O molecule abstracts proton
    • ​​e's collapse
      • and form a double bond

 

Methyl or hydride shifts can occur

if a more substituted CCI is available

51

Ketal

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51

Compare boiling points:

  • cis vs trans isomers

CIS > trans

  • b/c of dipole moment, there are increased IMFs in CIS
  • In TRANS, the dipoles cancel
    • which means you'll have less IMF's

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51

What is "anti" addition?

Where bonds are formed on OPPOSITE sides (of a metal catalyst, for example)

Remember:

Syn=Gay (same sex/sides; is a SIN)

Anti=Hetero (opposite sex/ sides)

52

List 4 characteristics of sigma bonds

1) DO allow rotation2) stronger than pi bonds3) more stable4) less reactive

53

What are Enantiomers?

What do they need to have in order to qualify as enantiomers?

non-superimposable mirror images

of each other

  • Compound needs to have at least 1 chiral center

54

Substitution of EPOXIDES can occur via what mechanism?

SN1 or SN2

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55

Describe E2 reactions

Rate depends on [ ] of two species

so its a SECOND order, one step reaction

STEP:

  1. Abstraction of H+ leads to double bond formation
    • ...while simultaneously ejecting LG

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56

Hybridization:

sp3, 2 LPs

Bent (V-shaped)

Ex: H2O

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57

What does it mean when two things are "GEMINAL?"

Both bonded to the same Carbon

(are gemelos--twins)

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58

Describe "NUCLEOPHILES"

  • How do they react with atoms around them?
  • Are electron dense/deficient?
  • What's their charge like?

  1. Attack C's
    • or other central atoms
  2. Are electron DENSE
    • just like bases
  3. Have a full or partial (-) charge

59

Ketone

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60

Acetal

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61

Gringard Synthesis

  • What is it?
  • What does it result in?
  • What 3 reactants can it use? 

  • Production of an ROH

...with an EXTENSION (!!) of the C chain

  • Results in increase in the number of C's
  • Can occur with the following reactants:
    • RMgBr (Main one)
    • Electrophilic DOUBLE BONDS
    • Cyano groups

62

What is it that determines a molecule's shape

and bond angle(s)?

Its Hybridization

sp vs sp2 vs sp3 etc.

63

Define "Stereoisomers"

list the 2 types

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Same MF, same connectivity

....but different 3D arrangement

2 Types:

  • Enantiomers & Diastereomers

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64

Acyl group

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65

When an alkene is 1 C away from another atom, the ___ ___s are electron ___

the π bonds are e' withdrawing

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67

Describe the 5 IUPAC rules for naming a compound

  1. Find the LONGEST C chain
  2. The terminal C closest to a substituent is #1
    • if it's a tie, one w/ next closest subst. is #1
  3. Order groups alphabetically
    • give # to match C to which it is attached
  4. Dont forget di, tri, tetra, etc if multiple copies of the same R group are present
  5. Put hyphens before and after R group #s

68

Mesyl group

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69

Hybridization (there's 3 possibilities for this one) and bond angle:

sp3d2 

90º

  1. Octahedral
  2. Square pyramidal (1 LP)
  3. Square planar (2 LP)

70

Amide

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71

Hybridization:

sp2, 1 LP

Bent (V-shaped)

Ex: SO2, O3

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72

Alcohols:

  • _,_,_ bonded to an H can act as H-bond donors/ acceptors?
  • What if they have LPs NOT attached to an H?

  • F,O,N can act as BOTH an H bond donor OR acceptor
  • F,O,N atoms w/ LPs that are NOT attached to a H
    • ...can only act as H bond acceptors

73

sp hybridization

always linear (180º)

75

Dextrorotary

cpd rotates light clockwise (+)

76

Protection of Alcohols: what 2 things protect alcohols? What do they protect them from?what thing will remove a protecting group?

  • TMS and MOM
  • protect OH from oxidation (or related rxn) while at the same time letting the rxn proceed
  • acidification will remote EITHER protecting group and restore ROH

77

Synthesis of an alkane

-reduce an alkene with H2 in presence of a metal catalyst (syn addition, remember?)

78

Anomers:if anomeric OH/OR group and CH2OH group are on the same side of the ring, what kind of anomer is it?

ß anomer

80

Vicinal

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81

Physical properties of Ethers

  • VERY non-reactive
  • weakly polar
  • ones with short R groups are slightly water soluble
  • most non-polar species are soluble in ethers
  • have low BP (no H bonding)
  • Ethers are excellent SOLVENTS!

82

Formation of an RX from an ROH: -what mechanism is it?-what makes it unique?

  • SN2 rxn
  • SN2 are usually one step, but alcohols need to get protonated first

83

___ ___ alkanes have the highest BP. Why?

-straight chain-always has higher MP than branched alkanes-among branched alkanes, increased branching=increased MP

84

Nucleophilicity is a function of ____?What does this mean?

-is a function of Kinetics-means it quantifies the rate at which a molecule reacts with an E:-describes how easily a molecule will react, but nothing about how stable the new bond will be

86

What are some common reducing agents?Reducing agents reduce a ___ to a __

  • NaBH4
  • LiAlH4
  • H2/pressure

    ...reduce a carbonyl to an alcohol

87

What is specific rotation of a sample?(hint: is ___ per___, per___)

  • "is observed rotation per length, per concentration unit"
  • divides observed rotation by length of tube and [ ]

88

Why is cyclohexane more stable than cyclopropane?

Cyclopropane has tons of RING STRAIN!

89

Tosyl

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90

NaBH4 can only reduce ___,___ ONLY

aldehydes and ketones only

91

Ether nomenclature

  • You can name each R group separately
  • IUPAC wants you to name the LONGER of the 2 R groups as the "parent" chain, and the other R group as a substituent w/ "-oxy" suffix added
    • ex: 1-ethoxyheptane

92

Which cyclic alkane is the most stable? How much ring strain does it have?

  • cyclohexane
  • has 0 ring strain

93

Alkynes are nearly identical to ___s in ___?

nearly identical to alkenes in how they react

94

Remember the following about enantiomers (3)

  1. they have R/S configurations at EVERY chiral center
  2. They rotate PPL to the same degree, but in different directions
  3. They have identical physical properties (BP, reactivity, etc) except for how they rotate PPL and the products they form when reacted with another chiral cpd

96

What does Valence Shell Electron Repulsion Theory predict?

  • predicts shape molecules take due to the repulsion of the LP's of electrons
    • ex: sp3 can be trigonal bipyramidal, seesaw, t-shaped, or linear depending on amount of LPs

97

Hybridization: 

sp3d2, no LPs

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98

What are E:'s?

  • e' poor species with a full or partial (+) charge
  • accept e's from either Nu:'s or bases

99

What is a polarimeter?

measures rotation of PPL as it passes through a sample

100

Hemiacetal

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102

Epoxide

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103

Basicity is a function of ____. What does this mean?

  • of Thermodynamics
  • basicity says nothing about how FAST a rxn will occur
    • Only shows how much the molecule "wants" to react (how stable it is)

104

Alcohol MP properties

  • increased MP with:
    • increased Polarity and H-bonding

106

Describe SN1 rxns

  • Rate depends on [ ] of one species, so its FIRST order-two steps
    1. LG leaves, forms CCI (slow step)
    2. Nu: attacks CCI (fast step)

107

Epoxides suffer from SEVERE what?What does this mean?

  • Ring strain!
  • This means they are highly reactive

109

Conformational Isomers

  • AREN'T really isomers!
  • when a molecule rotates around its bonds, these are "conformers," not isomers
    • think about Newman projections, staggered & eclipsed, etc.

110

Nitro (FG)

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111

Ether

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112

Compare melting points: cis vs trans isomers

TRANS>CIS

113

What are Epimers?What are a common example?

  • A type of diastereomer
  • differ are only 1 chiral center
  • many carbohydrates are epimers

114

Epoxides are ___ ___ involving what?

cyclic ethers with 1 O and 2 Cs in a 3-membered ring

116

What should you know about Radicals? (2)

  1. Its HETEROLYTIC cleavage sends ONE e' to one species and ONE to the other
  2. can also form as damage to the molecule itself (radiation exposure)

118

Aryl

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119

What is stronger, a sigma or a π bond?

sigma

120

Geometric Isomers: what are they when there's only 2 R groups attached? What about when there's more than 2?

2 groups: cis (same side), trans (opposite side)2+ groups: E (epposite side), Z (ze zame zide)(prioritize by MW)

121

Remember the following about cis & trans isomers (2)

  1. Cis isomers often have dipole moments, but trans DONT (they cancel)
  2. Cis isomers often experience steric hindrance, but trans DONT

122

Carbonyl

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124

Hydroxyl

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125

To be chiral, an atom has to be attached to...?What if it isn't?

  • to 4 DIFFERENT R groups
  • if it isnt, its not chiral
    • therefore not an enantiomer

126

Hybridization: 

sp3d2, 2 LPs

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127

The Pinacol Rearrangement ("vicinal")-what does the rxn look like?-3 other details

  • vicinal diol+hot acid-->ketone or aldehyde
  • the two OH groups must be in vicinal position and C's bearing them must be tri- or tetra- substituted by R groups
    • if tri-substituted, yields an aldehyde
    • if tetra-substituted, yields ketone

128

What are Leaving Groups?What are the "best" LGs?

  • they leave the parent molecule during a rxn and take BOTH e's from the bond with them
  • Best LG's are the most stable after they leave
    • (ex: Halides)

129

Alkene stability

More R groups=more stable3>2>1

130

Alkoxy

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131

sp3d bond angle and hybridization (4)

  • 90º/120º or 180º (for linear)
  1. trigonal bipyramidal
  2. seesaw (1LP)
  3. t-shaped (2LP)
  4. linear (3LP)

132

sp3 bond angle and hybridization (3)

  • 109.5º
  1. tetrahedral
  2. trigonal pyramidal (1LP)
  3. bent (2LP)

133

What is plane polarized light?What is "optically active?"

  • Light that exists in only a single plane
  • "optically active"= DOES rotate PPL

134

How do you find the max # of (optically active) stereoisomers?

  • =2n
  • "n"=# of chiral centers

135

What catalyzes epoxide rxns, and how?

  • Strong acids
    • By protonating O and making it a better LG

136

Describe E1 rxns

  1. Depends on [ ] of ONE species, so its first order
  2. Two-steps:
    1. LG leaves, forms CCI (slow step)
    2. Proton abstraction leads to double bond formation (fast step)

137

sp2 hybridization (2) and bond angle

  • 120º
  1. trigonal planar
  2. bent (1LP)

138

Alcohol BP properties

  • increased BP with increased MW
  • decreased BP with increased BP

139

Combustion of an alkane is a ___, ___thermic reaction with a ___ Ea

  • radical, exothermic rxn with a High Ea

140

What are Anomers?

  • a type of diastereomer
  • differ in 3D orientation ONLY at the anomeric carbon (1') of a ring structure

141

Hybridization: 

sp3d, 1 LP

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142

What are the 3 steps of a radical reaction?

  1. initiation
  2. propagation
  3. termination

143

Which step of a radical rxn produces the most product?

propagation 

144

PEROXIDES

RO-OR

145

HYDROGEN PEROXIDE

H2O2

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146

Hückel's Rule (for aromaticity) 

  • Why is benzene aromatic and the 8-membered ring NOT?

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4n+2π

  • "n" is just any interger. But it needs to equal the amount of carbons!
  • Benzene: here, "n"=1
    • ​4(1)+2π=6 
  • ​For the 8 membered ring, neither n=1 nor n=2 works!
  • You can't get 8 from either option
    • therefore it isnt aromatic