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organic chem > ch 19: amines > Flashcards

ch 19: amines Flashcards

(57 cards)

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1
Q

primary amine

A

has one alkyl group bonded to the nitrogen (RNH2)

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2
Q

secondary amine

A

has two alkyl groups bonded to the nitrogen (R2NH)

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3
Q

tertiary amine

A

has three alkyl groups bonded to the nitrogen (R3N)

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4
Q

quaternary amine

A

has four alkyl groups bonded to the nitrogen and the nitrogen has a positive charge (R4N+)

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5
Q

are primary amines basic?

A

yes due to lone pair

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6
Q

are secondary amines basic?

A

yes due to lone pair

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7
Q

are tertiary amines basic?

A

yes due to lone pair

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8
Q

are quaternary amines basic?

A

no, because there is no lone pair and it has a partial positive charge

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9
Q

IUPAC for primary amines

A

find the longest carbon chain bonded to the N and change the -e ending of parent chain to -amine

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10
Q

simple common names for amines

A

name the alkyl group bonded to the N and add amine to the end

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11
Q

naming secondary and tertiary amines with identical alkyl groups

A

use the prefix di- or tri- with the name of the primary amine

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12
Q

naming amines with different R groups

A

use the largest R for core name, then name the other R groups in front
- use prefix N- to show that R’s are attached to the N

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13
Q

how are amino benzenes named?

A

as a derivative of aniline

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14
Q

what is the hybridization of N in an amine?

A

sp3 and trigonal pyramidal with bond angles of 109.5

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15
Q

how many groups does an amine have?

A

counting the lone pair, technically has 4

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16
Q

are amines with lone pairs chiral?

A

no, because the lone pair can move locations making it achiral

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17
Q

are ammonium salts chiral?

A

yes because there are 4 different groups attached to the N

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18
Q

physical properties of amines

A

dipole-dipole interactions and hydrogen bonding but weaker than OH bond due to N being less electronegative than O

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19
Q

what does a secondary amine have a higher boiling point than tertiary amine?

A

because tertiary amines are hydrogen bond acceptors but not donors because they do not have an N-H bond

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20
Q

what are amines more basic than?

A

H2O, ROH, and ROR

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21
Q

how to determine the basicity of amines?

A

less H bonds, means more basic
- NH2 is more basic than NH3

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22
Q

what are acidic amines soluble in?

A

H2O but insoluble in Ch2Cl2

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23
Q

what are basic amines soluble in?

Study These Flashcards
A

soluble in CH2Cl2
insoluble in H2O

24
Q

how can relative basicity of amines be compared?

Study These Flashcards
A

by using the pKa values of their conjugate acids
- stronger the acid, weaker the base

25
effects of alkyl groups on amine basicity
electron donating groups increase basicity due to increasing electron density and electron withdrawing groups decrease basicity and increase acidity due to decreasing electron density
26
basicity of aryl vs alkyl amines
aryl amines are less basic due to the electron delocalization onto the benzene ring via resonance, this decreases the electron density which decreases basicity
27
what does adding electron donating groups to aniline do?
makes it more basic than aniline
28
what does adding electron withdrawing groups to aniline do?
makes it less basic than aniline
29
basicity of amines vs amides
amides are less basic than amines because the electron lone pair is delocalized in an amide onto the C=O oxygen by resonance - electron lone pair is localized on the N atom in an anime
30
amide basicity
protonation of an amide will occur at the C=O not the N due to resonance stabilization
31
basicity of heterocyclic amines
- if the lone pair is outside the aromatic, it is basic - if the lone pair is apart of aromatic ring, it is not basic because it cannot react with a lewis acid
32
hybridization effects on basicity of amines
N with sp3 orbitals are more basic because their lone pair is more available to react and has lower s character, not tightly bound to the atom
33
what can be used to prepare primary amines from RX
SN2 by using a large excess of NH3, and for preparing quaternary ammonium salts - NH3 attacks R and R releases Br as a leaving group and primary amine is created
34
amide synthesis with acid chlorides
1. nucleophile attacks the carbonyl carbon of acid chloride, forming a tetrahedral intermediate with NH2R attached to carbon 2. expulsion of chloride ion 3. loss of proton gives the amide DO MECHANISM
35
what reaction can aniline not undergo?
friedel crafts reaction because NH2 reacting with AlCl3 forms an unreactive complex
36
what group can undergo friedel crafts reactions?
amides
37
amide friedel craft reaction
1. protection by acetyl group 2. friedel-crafts reaction by RCl, AlCl3 - adds R to the ortho position 3. deprotection by H3O+ and H2O or OH DO MECHANISM
38
Hoffman Elimination
converts an amine into an alkene
39
steps of hoffman elimination
1. create a good leaving group (:NR3) by forming a quaternary ammonium salt by using CH3I 2. indirectly provide a strong base (OH) needed for step 3 by using Ag2O 3. E2 elimination that forms a new pi bond
40
what is the major alkene in the hoffman elimination?
the alkene that has the less substituted C=C
41
Cope Elimination
tertiary amines are oxidized to amine-N-oxides by H2O2 or per-acids
42
what can happen to the N-oxide in the cope elimination?
it can undergo elimination to form an alkene - less substituted alkene is favored if there are 2 or more beta hydrogens
43
formation of diazonium salts
nitrous acid (HNO2) is formed from NaNO2 and HCl 1. O of NaNO2 attacks H in HCl which creates HO-N=O
44
diazotization
primary amine become aryl diazonium salt KNOW MECHANISM
45
what reagent is used for diazotization
NaNO2/HCl - replaces NH2 with N2 and Cl adds to the N2
46
what is the N2 group used for?
good leaving group, so it can react with nucleophiles
47
formation of phenol
reagent: Cu2O, Cu2+, H2O - replaces N2 with OH to form phenol
48
sandmeyer reaction
CuCl or CuBr is used to form aryl chlorides or bromides - replaces N2 with Br or Cl
49
formation of aryl fluorides or iodides
use HBF4, NaI or KI - replaces N2 with F or I
50
formation of aryl nitriles
reagent: CuCN - N2 is replaced with CN
51
formation of benzene
reagent: H3PO2 - N2 is replaced with H
52
aryl diazonium salts forming substituted benzenes
1. nitration by HNO3/H2SO4 to give NO2 2. reduction by H2/Pd-C to reduce NO2 to NH2 3. diazotization by NaNO2/HCl to add N2Cl 4. substitution by Z to replace N2 with Z
53
conversion of aryldiazonium salts to azo compounds
N2 is attacked by a strong nucleophile such as NR2 or phenols to join to another aromatic compound KNOW MECHANISM
54
reductive amination
converts aldehydes and ketones into primary, secondary or tertiary amines - C=O gets replaced by C-N and C-H bonds
55
reductive amination steps
1. nucleophilic attack of NH2 on the C=O forms an amine 2. reduction of the imine using H source forms an amine
56
reagents used for the second step of reductive amination
NaBH2CN, LiAlH4, NaBH4, NaBH(OAc)3, H2/metal catalyst
57
gabriel synthesis of primary amines
two step process that uses a nucleophile derived from phthalimide to synthesize primary amines KNOW MECHANISM

organic chem (14 decks)

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