Chem 1152: Ch. 16
Amines
NitrogenNitrogen• Mostly inert gas (N2) under standard conditions
• ~78% of atmosphere• Found in:
– Ammonia (NH3)
– Nitrates (fertilizers)– Nitric acid (HNO3)
– Propellants (N2O, nitrous oxide)
– Explosives (nitroglycerine)– Cyanides (CN-)
• 4th most abundant element in human body• Critical to building blocks of life/CNS function
– Proteins– DNA– RNA– Neurotransmitters
R
O
O-
NH3+
Amino acid
nitroglycerine
AminesAmines• Organic derivatives of ammonia• One or more H atoms replaced by aromatic or alkyl group
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
ammonia
Primary (1°) Secondary (2°) Tertiary (3°)
H
HH
N:
R O
R R
HR O
R H
HR O
H H
Halcohols
R
HH
N
R
HR
N
R
RR
N: : :
R-OH
Naming Amines – Common NamesNaming Amines – Common Names• Common names• For low MW amines• Alphabetically link names of alkyl or aromatic groups bonded to nitrogen, attach suffix –amine.
H
HCH3N CH3
H
CH3N
CH3
CH3CH3N
methylamine ethylmethylamine trimethylamine
H
CH3N
CH3
H
H
N
propylaminemethylphenylamine
Naming Amines – IUPAC NamesNaming Amines – IUPAC Names• Replace –e in alkane with –amine.• Number position of amino group lowest on parent chain.• If substituent on nitrogen, prefixed with N.
NH2
CH3CH3
NH2
CH3
CH3
CH3NH
CH3CH3
NH2
CH3CH3
CH3NH
CH3CH3
CH3 CH3N
CH3CH3
CH3CH3
N
CH3CH3
NH2
NH2
CH3CH3
NH2
Naming Amines – IUPAC NamesNaming Amines – IUPAC Names• Replace –e in alkane with –amine.• Number position of amino group lowest on parent chain.• If substituent on nitrogen, prefixed with N.
3-Pentanamine
NH2
CH3CH3
3-Methyl-1-butanamine
NH2
CH3
CH3
CH3NH
CH3CH3
N-Methyl-2-butanamine
NH2
CH3CH3
2-Hexanamine
CH3NH
CH3CH3
CH3 CH3N
CH3CH3
N-Methyl-2-hexanamine N,N-Dimethyl-2-hexanamine
CH3CH3
N
CH3CH3
NH2
NH2
CH3CH3
NH2
N-Ethyl-N-methyl-2-hexanamine 2,5-hexanediamine cyclohexylamine
Naming Amines – AromaticsNaming Amines – Aromatics
aniline 3-Ethylaniline
N-Ethyl-N-methylaniline
2-Methylaniline
• Usually named as substituted anilines• For groups on N of aniline, identify with N to indicate not attached to
ringNH2
CH3
NH2CH3
NH2 CH3NH
N-Ethylaniline
CH3
CH3N
CH3
CH3N
N,N-dimethylaniline
H
N
diphenylamine
CH3
H
CH3N
2-Ethyl-N-methylaniline
CH3
CH3
H
N
N-Ethyl-2-methylaniline
NH2
CH3 CH3
3-phenyl-2-heptanamine
Physical Properties of AminesPhysical Properties of Amines• 1° and 2° amines form H-bonds among themselves• Bonds weaker for amines than alcohols (EN of oxygen > nitrogen)
• BP’s of 1° and 2° amines lower than alcohols of comparable MWH
CH3 O H
CH3
O
alcohol amine
• Amines with fewer than 6 C’s (1°, 2° and 3°) soluble in water due to H-bonding
• Amines stink!• Low MW amines smell like ammonia• Higher MW amines smell like rotten fish
NH2NH2
NH2NH2
putrescine
cadaverine
Chemical Properties of AminesChemical Properties of Amines• Basicity: Amines are weak bases
From Brønsted-LowryBase accepts proton and becomes a conjugate acid
Chemical Reactions of AminesChemical Reactions of Amines• Amines reversibly react with water, form hydroxide ions
RNH2 + OH2 + OH
-
RNH3
+
+ OH2 + OH-CH3
NH2
CH3
NH3+
• Amines form salts when they react with acids
RNH2 + ClH Cl
-
RNH3
+
+ ClHCl-
CH3
NH2
CH3
NH3+
+ OH
O
CH3
CH3
CH3
NH2
CH3
CH3
NH3+O-
O
CH3
Amine SaltsAmine SaltsNaming: Change amine to ammonium and add name of negative ion derived from acid
HCH3
CH2CH3
CH3
N+
Ethyldimethylamine (common)
N,N-dimethylethanamine (IUPAC)
BrCH3
CH2CH3
CH3
N+
ethyldimethylammonium bromide
• Amine salts are white crystalline solids with high MP’s.• Amine drugs usually given in form of salts to improve their ability to
dissolve in body fluids
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
ethyldimethylammonium
Amine SaltsAmine SaltsAmine salts are pH dependent, like CA’s.
H
R
H
H N+
R
H
H NH+
OH-
amine(high pH)
amine salt(low pH)
Amine salts may have 4 alkyl/benzene groups quaternary ammonium salts
Acetylcholine is important QA salt involved in transmission of nerve impulses
Some QA salts have antiseptic qualities that kill bacteria and fungii. e.g. benzalkonium (Zephiran) chloride used by physicians to scrub before
surgery and to sterilize instruments
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
R
HH
N
AmidesAmidesAmides are combination of CA and ammonia or amine joined by amide linkage.
H
H
R
O
N
Ammonia or amine
Amide linkage
RR
O
O
Carboxylic AcidCarboxylic Acid
AlcoholEster linkage
Amide Ester
Not formed by reaction between CA and amine (produces salt)
+ OH
O
CH3
CH3
CH3
NH2
CH3
CH3
NH3+O-
O
CH3
Amines Form AmidesAmines Form Amides Amides are formed through reaction of primary and secondary amines
with acid chlorides and acid anhydrides. Similar to esterification reactions.
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Amide ReactionsAmide Reactions
O O
CH3 O CH3+
CH3
NH2
O
OH CH3CH3
NH
O
CH3
+
O O
CH3 O CH3+
CH3
CH3
NH
O
OH CH3+
CH3
CH3
N
O
CH3
O O
CH3 O CH3+
CH3
CH3
CH3
N No Rxn
O
CH3 Cl+ CH3NH2
O
Cl + CH3CH3NH
+CH3NH
O
CH3ClH
CH3
CH3O
N + ClH
Synthesis of NylonSynthesis of Nylon
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
CarpetingClothingMedical tubingSuturesParachutes
Aspirin SubstitutesAspirin Substitutes
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Acetylsalicylic acid
AspirinPain relieverFever reducerAnti-inflammatory
Harmful side effectsAllergic reactionsGastrointestinal bleedingCan induce Reye’s syndrome in children
AcetaminophenPain relieverFever reducerDoes not irritate intestinal tractNegativesNot an anti-inflammatoryOveruse can lead to liver and kidney damage
Amines as NeurotransmittersAmines as Neurotransmitters
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Neurotransmitters: Molecules that carry chemical messages between neurons in nervous systemreleased into synapse (gap between synaptic terminal of one neuron and Dendrite of another) in response to electrical signalDiffuse across synapse and bind to receptors on dendrites of next neuron
neur
on
Amines as NeurotransmittersAmines as Neurotransmitters
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
In CNS (brain and spinal cord), the most important neurotransmitters are amines: Acetylcholine Norepinephrine Dopamine Serotonin
In addition to being chemical messengers, some neurotransmitters may also be partly responsible for moods, mental illness
Amines and Mental IllnessAmines and Mental Illness
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Neurotransmitters dopamine and norepinephrin both derived from tyrosine Tyrosine essential AA obtained from diet (egg whites, turkey, soy)
Norepinephrine and epinephrine (adrenaline) act as drugs related to fight or flight response
directly increasing heart rate triggers the release of glucose from energy stores increases blood flow to skeletal muscle increases the brain's oxygen supply
Excess norepinephrine (NE) results in feelings of elation Low NE levels may cause depression
Amines and Mental IllnessAmines and Mental Illness
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Derived from the AA tryptophan, another essential AA obtained from diet Influences sleeping, regulation of body temp., sensory perception May be related to mental illness
AmphetaminesAmphetamines
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Amphetamines structurally and chemically similar to adrenaline Raise glucose level in blood Increase pulse rate Increase blood pressure
May be legally prescribed to elevate mood or reduce fatigue Street names:
Bennies, pep pills, Reds, red devils, speed, dexies, uppers
AlkaloidsAlkaloids
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Weakly basic amines derived from plants
Stimulate CNS/Resp. systems Treatment of malaria
CNS Depressants, used as painkillers Morphine derivative
Naming AmidesNaming Amides• Simple amides named after corresponding carboxylic acids
by changing –ic or –oic of acid to –amide.• Common names are used more often than IUPAC names.
formic acid
H
O
OH H
O
NH2
Common nameIUPAC name methanoic acid
formamidemethanamide
acetic acidCommon nameIUPAC name ethanoic acid
acetamideethanamide
CH3
O
OH CH3
O
NH2
benzoic acidCommon nameIUPAC name benzoic acid
benzamidebenzamide
O
OH
O
NH2
Naming AmidesNaming Amides• Simple amides named after corresponding carboxylic acids by changing –ic or –
oic of acid to –amide.• Common names are used more often than IUPAC names.• Use italicized capital N to identify alkyl groups bonded to nitrogen.
N-methylformamideCommonIUPAC
CH3H
O
NH
N-methylmethanamide
CH3
CH3CH3
O
N
N,N-dimethylacetamideN,N-dimethylethanamide
CH3
CH3O
N
N-ethyl-N-methylbenzamide
N-ethyl-N-methylbenzamide
Naming AmidesNaming Amides• Simple amides named after corresponding carboxylic acids by changing –ic or –
oic of acid to –amide.• Common names are used more often than IUPAC names.• Use italicized capital N to identify alkyl groups bonded to nitrogen.
N,N-diethylethanamide
CH3
CH3
CH3
O
N
CH3
CH3CH3
H
O
N
N-isobutylbutanamide
CH3
O
N
N-ethyl-N-phenylbenzamide
CH3
CH3
O
NH
2,N-dimethylbenzamide
Physical Properties of AmidesPhysical Properties of Amides• Unsubstituted amides can form complex networks of
intermolecular H-bonds– Increases MP’s of these substances
• Increasing the number of substituents on amide reduces H-bonding– Reduces MP’s and BP’s
• Amides do form H-bonds with water– Increases solubility
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Amide HydrolysisAmide Hydrolysis• Most important rxn is hydrolysis• May involve either acid or base• One of the products will always be a salt
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Amide HydrolysisAmide Hydrolysis
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Amide HydrolysisAmide Hydrolysis
O
CH3 NH2+ HOH + ClH
HeatO
CH3 OH NH4+Cl-+
acetamide Acetic acid Ammonium chloride
+ HOH + ClHHeat
CH3
O
CH3 NH
O
CH3 OH Cl-+ CH3 NH3
+
N-methylacetamide Acetic acid methylammonium chloride
+Heat
CH3
O
CH3 NHOHNa
O
CH3 O-
NH2CH3+Na
+
N-methylacetamide Sodium acetate
methylamine
Amide HydrolysisAmide Hydrolysis
N-ethylbenzamide Benzoic acid Ethylammonium chloride
+ HOH + ClHHeat
CH3O
NH
Cl-+
CH3
NH3+
OH
O
+Heat
CH3O
NH
OHNa +CH3
NH2
O-
O
Na+
N-ethylbenzamide Sodium benzoate
Ethylamine
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