Lecture 1 (Intro to MedChem) Flashcards

1
Q

What is a lead compound?

A

A lead compound is like the first draft of a drug. It has the correct pharmacological effect but it is not perfect. It most likely needs to be tweaked to obtain the most optimal and effective drug function.

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2
Q

How are drugs improved?

A

By using a SAR (structure activity relationship) we can turn lead compounds into safe and effective drugs.

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3
Q

Two types of SARs?

A

Quantitative (QSAR)
Qualitative (SAR)
-this is the only one we are concerned with

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4
Q

How is a QSAR used?

A

Uses a mathematical relationship between PHYSICOCHEMICAL PROPERTIES to their pharmacological activity to predict the most potent structure.

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5
Q

Why won’t we be studying QSAR?

A

Because it cannot easily be extrapolated to new drugs. It requires extensive research for each drug.

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6
Q

How is a SAR used?

A

-uses the relationship of the STRUCTURE (arrangement of the functional groups) and the pharmacological activity of the drug

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7
Q

What are the chemical properties of drugs we need to consider?

A
  • placement of covalent bonds
  • EN
  • electron effects of functional groups
    - ED (electron donating)
    - EW (electron withdrawing)
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8
Q

What drug properties are going to be affected by different things?

A
  • potency absorption
  • distribution
  • metabolic profile
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9
Q

Describe sigma bonds

A
  • single bonds
  • formed by hybrid orbitals
  • free rotation around this bond
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10
Q

Describe pi bonds

A
  • double bonds
  • formed by overlapping P orbitals
  • no free rotation around this double bond
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11
Q

Define EN

A

ability to attract electron density

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12
Q

How does EN increase on the periodic table?

A

to the right and up it increases

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13
Q

What 2 ways can electron density move through a molecule?

A
  • resonance

- induction

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14
Q

Define resonance

A

movement of electron density through pi bonds (conjugated system)

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15
Q

Every 1st bond is ____?

A

sigma

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16
Q

Every 2nd or 3rd bond is ___?

A

pi

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17
Q

What are sigma bonds made from?

A

hybridized orbitals (sp)

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18
Q

What are pi bonds made from?

A

leftover p orbitals

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19
Q

Define induction

A

movement of electron density through sigma bonds (saturated carbons)

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20
Q

How do you determine whether a functional group with be ED or EW?

A

Depends on:

  • EN
  • presence of lone pair electrons
  • multiple bonds (geometry of the molecule)
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21
Q

Electronegative atoms with a lone pair (excluding halogens) are __ through _________.

A

ED

resonance

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22
Q

Alkyl groups - the more branched, the more _____.

A

donating

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23
Q

Attached group with a double bond O or N or triple bond N are __ through __________.

A

EW

resonance

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24
Q

pKa _____ for acids

A

low (inverse of Ka)

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25
Q

Ka ____ for acids

A

high (if they dissociate there is more of the ions than the acid - so a bigger number/ smaller number = high number)

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26
Q

pKa ____ for bases

A

high (inverse of Ka)

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27
Q

Ka ______ for bases

A

low (bases don’t like to dissociate so there would be less of the ions than the base - small number/big number = low number)

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28
Q

Ratio of ionization of a weak acid is what ratio?

A

[HA] / [A-]

unionized: ionized

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29
Q

Ratio of ionization of a weak base is what ratio?

A

[HB+] / [B]

ionized: unionized

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30
Q

To maximize ionization of HA to A-

A

pH > pKa

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31
Q

To minimize ionization of HA to A-

A

pKa > pH

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32
Q

To maximize ionization of B to HB+

A

pKa > pH

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33
Q

To minimize ionization of B to HB+

A

pH > pKa

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34
Q

We use pKa to measure ___ ________.

A

drug ionization

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35
Q

We always assume the solvent is _____?

A

WATER BITCHES

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36
Q

When we talk about the pKa of a base we will most likely be talking about ??

A

primary, secondary, or tertiary amines

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37
Q

What is the difference between primary, secondary, and tertiary amines?

A

Primary:
The N is attached to 1 R group and 2 H’s

Secondary:
The N is attached to 2 R groups and 1 H

Tertiary:
The N is attached to 3 R groups

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38
Q

How does the scale of basicity go for amines?

A

Secondary > Primary > Tertiary

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39
Q

What is a substituent?

A

-an atom or group of atoms substituted in place of a HYDROGEN on the parent organic compound

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40
Q

Describe alkanes

A

-tetrahedral
-sp3 hybrid
-bond angle 109.5
C-C bond length 1.5A
-non-polar (hydrophobic)
-ED ALWAYS

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41
Q

Describe alkenes

A

-planar
-sp2 hybrid
-bond angle 120
C=C bond length 1.3A
-non-polar (but depends what R groups are)
-usually ED but can be EW depending on substituents

42
Q

Describe alkynes

A
  • sp hybrid
  • bond angle 180
  • C=-C (triple bond) bond length 1.2A
  • non polar (hydrophobic)
  • mostly EW
43
Q

Are alkanes and alkenes water soluble?

A

No way jose

44
Q

What happens when an alkane or alkene gets larger or more branched?

A

Becomes less hydrophilic or more lipophilic

45
Q

Halogenated hydrocarbons are generally less _____ than the alkyl form.

A

hydrophilic

46
Q

Halogenated hydrocarbons are ______.

A

hydrophobic

47
Q

Halogens on saturated hydrocarbons are ___ by _______.

A

EW

induction

48
Q

Why are alcohols more water soluble?

A

They have an OH group (hydroxyl) which increases polarity and therefore makes it more water soluble because water is also a polar molecule.

49
Q

Describe the hybridization and geometry of alcohols

A

sp3 hybridization

tetrahedral

50
Q

Alcohols from bonds with water through what type of bond?

A

Hydrogen bond

51
Q

How is an OH ED?

A

through resonance

52
Q

How is an OH EW?

A

through induction

53
Q

T or F: an alcohol only accepts hydrogen bonds

A

FALSE

alcohols are H bond donors and acceptors

54
Q

Why do alcohols have a permanent dipole?

A

EN oxygen
positive hydrogen

*those two bad boys result in a permanent freaking dipole

55
Q

With increasing length of hydrocarbon chain on an alcohol - how does that affect solubility?

A

decreases solubility

56
Q

Are alcohols very acidic?

A

NO WAY JOSE

57
Q

Does alcohol solubility depend on location of OH?

A

yeah man

58
Q

Describe a phenol

A

-special type of alcohol

59
Q

Are phenols generally more acidic (more acidic means LOWER pKa) than aliphatic alcohols?

*slide 37

A

you bet your ass they are :D

60
Q

aromatic hydrocarbons are ________

A

hydrophobic

61
Q

SH (sulfhydryl) groups are ALWAYS __?

A

ED (sulfur is not very EN so it’s not going to withdraw - it will donate)

62
Q

SH group is _____ polar

A

weakly

63
Q

RSH is more _____ than ROH

A

acidic

64
Q

R-O-R is a ??

A

ether

65
Q

R-S-R is a ???

A

thioether

66
Q

ethers and thioethers are weakly _____

A

polar

67
Q

SR (thioalkoxy) is ____

A

ED

68
Q

OR (alkoxy) is ____

A

ED/EW

69
Q

sulfoxide is always ___

A

EW

70
Q

sulfone is always __

A

EW

71
Q

Describe the hybridization and geometry of aldehydes and ketones

A

sp2 hybridization

planar

72
Q

aldehydes and ketones are always __

A

EW (they have an oxygen which is highly EN) - so therefore it will withdraw electrons

73
Q

aldehydes and ketones are in rapid equilibrium with ____ to form hemiketals and hemiacetals

A

alcohol

74
Q

_____ have an sp3 tetrahedral N centre

A

amines

75
Q

Are amines basic or acidic?

A

basic

76
Q

Are amines polar?

A

yeah man

77
Q

The N of amines are basic due to what?

A

free lone pair of electrons

78
Q

describe the hybridization and geometry of carboxylic acids (RCOOH)

A

sp2

planar

79
Q

Are carboxylic acids polar?

A

yes

80
Q

neutral form of carboxylic acids are ____

A

EW

81
Q

anionic form of carboxylic acids are ____

A

ED

82
Q

Are esters (RCOOR) polar?

A

yes

83
Q

Are esters (RCOOR) ED or EW?

A

EW

84
Q

esters are susceptible to _____

A

hydrolysis

85
Q

What are esters frequently incorporated for?

A

To facilitate absorption of carboxylic acid drugs (they act as a pro drug)

86
Q

Describe hybridization and geometry of amides

A

sp2

planar

87
Q

are amides polar?

A

heck yes (napoleon dynamite voice)

88
Q

Is the N of an amide (RCONHR) basic?

A

NO (because lone pair of electrons forms resonance structure and therefore is not available to accept a proton)

  • N of amine = basic
  • N of amide = not basic
89
Q

The H of RCONHR (amide) is usually ___?

A

only very weakly acidic

90
Q

Are amidines and guanidine’s polar?

A

YES

91
Q

In neutral form amidines are ___

A

EW

92
Q

In neutral form guanidine’s are ___?

A

weakly EW and weakly ED due to electronegative nature of the N

*see slide 48 for details of structure

93
Q

In ionized form, both amidines and guanidine’s are ___

A

EW

94
Q

Are amidines and guanidine’s less basic than amines?

A

No, they are more basic.

95
Q

Are Nitro (RNO2) highly EW or ED?

A

EW all the way

96
Q

Is the negative charge on the O in a nitro (RNO2) able to accept a proton?

A

no way man

97
Q

Describe hybridization and geometry of sulfonic acids and sulfonamides

A

sp3

tetrahedral

98
Q

T or F: sulfonic acids and sulfonamides are highly polar and EW

A

true true true

99
Q

Heterocycles usually contain what 3 elements?

A

S, O, and N

100
Q

Drugs with a 3 or 4 membered ring (heterocycle) are usually ???

A

strained and unstable (like me after a night of drinking)

101
Q

What are the requirements for a structure to be aromatic?

A

cyclic
planar
4n+2
delocalized conjugated (every atom in the ring has p orbitals capable of forming pi bonds)