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Introduc)on to Func)onal Groups in Organic Molecules
OC
N
CH3
C
CN
CH3
CH
N
NH3C C
O
Caffeine
Func)onal Group
• Func%onal group -‐ collec)on of atoms at a site that have a characteris)c behavior in all molecules where it occurs
• The group reacts in a typical way, generally independent of the rest of the molecule
• For example, the double bonds in simple and complex alkenes react with bromine in the same way
Family and Func)onali)es in Organic Molecules
Hydrocarbon Family
• Alkane • Alkene • Alkyne • Arene
Heteroatom-‐ Subs)tuted
Hydrocarbon Family
• Haloalkane or alkyl halide
• Alcohol • Ether • Amine • Nitrile • Nitro • Sulfide • Sulfoxide • Sulfone • Thiol
Carbonyl Family
• Aldehyde • Ketone • Carboxylic Acid • Acid chloride • Anhydride • Ester • Lactone • Amide • Lactame
Alkanes, R-‐H
• Alkanes: Compounds with C-‐C single bonds and C-‐H bonds only (no func)onal groups), non-‐polar molecule
• Easy to rotate around C-‐C single bonds • Connec)ng carbons can lead to large or small molecules
• The formula for an alkane with no rings in it must be CnH2n+2 where the number of C’s is n
• Alkanes are saturated with hydrogen (no more can be added
• They are also called alipha%c compounds
Alkanes
C4H10 can be arranged in two ways:
C5H12 can be arranged in three ways:
These are cons)tu)onal isomers: the same molecular formula but the atoms are linked differently.
Alkanes
C6H14 can be arranged in five ways:
Cons)tu)onal Isomers (Structural Isomers)
Chain
• Different carbon chains
• Hexane and 2-‐Methylpentane
Posi)onal
• Different posi)ons • 2-‐Methylpentane 3-‐Methylpentane
• 1-‐Butanol and 2-‐Butanol
Func)onal Group
• Different Func)onality
• Ethanol and dimethyl ether
Alkanes, R-‐H
• Alkanes with C’s connected to no more than 2 other C’s are straight-‐chain or normal alkanes
• Alkanes with one or more C’s connected to 3 or 4 C’s are branched-‐chain alkanes
• Butane and pentane are straight-‐chain alkanes • Isobutane, isopentane, and 2,2-‐dimethylpropane are branched-‐chain alkanes
Classifica)on of Carbons in a Molecule
A primary carbon is bonded to one carbon.
A secondary carbon is bonded to two carbons.
A ter)ary carbon is bonded to three carbons.
Primary hydrogens are a^ached to primary carbons.
Secondary hydrogens are a^ached to secondary carbons.
Ter)ary hydrogens are a^ached to ter)ary carbons.
• We can represent an alkane in a brief form or in many types of extended form
• A condensed structure does not show bonds but lists atoms, such as – CH3CH2CH2CH3 (butane) – CH3(CH2)2CH3 (butane)
Structural formulas
Condensed Structures of Alkanes
Condensed and Line Structures
• Condensed structure of Butane
• Line structure of Butane
Cycloalkanes, CnH2n
Bond Angles in Planar Cyclic Alkanes
• Also called an olefin but alkene is be^er • Hydrocarbon that contains a C-‐C double bond, CnH2n formula
• Unsaturated hydrocarbon, non-‐polar molecule
• No rota)on around C-‐C double bond, planar molecule • Includes many naturally occurring materials
– Flavors, fragrances, vitamins
Alkenes -‐ Hydrocarbon With Carbon-‐Carbon Double Bond
Classifica)on of Alkenes
• Ethene is the simplest alkene
• Subs)tu)ng one of the hydrogen from ethene by an alkyl group leads to monosubs)tuted alkene
• Disubs)tuted alkenes can be classified as
H H
H H
H CH3
H H
H R
H H
Ethene Propene Monosubstitued alkene
R H
R H
R H
H R
R R
H H
Geminal trans cis
Classifica)on of Alkenes
• Trisubs)tuted alkene
• Tetrasubs)tued alkene
R R
H R
R R
R R
Cycloalkenes, CnH2n-‐2
Cyclopropene Cyclobutene Cyclopenten Cyclohexene
Cycloheptene Cyclooctene 1,4,5-Triethylcyclohex-1-ene
Molecules with More than one Double Bond
• If molecule has two double bonds, called diene
• If molecule has three double bonds, called triene
• Four double bonds called tetraene, and so on
Types of Dienes
• Diene can be classified as conjugated
• If they are separated by only one single bond they are conjugated and their orbitals interact
• The conjugated diene 1,3-‐butadiene has proper)es that are very different from those of the nonconjugated diene (isolated diene), 1,4-‐pentadiene.
Alkenes Classifica)on
Classify the following alkenes:
O
Alkynes, CnH2n-‐2
• Hydrocarbon that contains a C-‐C triple bond, CnH2n-‐2 formula
• Unsaturated hydrocarbon, non-‐polar molecule
• Ethyne, also known as acetylene with molecular formula C2H2
• Structure of Ethyne is
• Mono-‐subs)tuted alkyne or terminal alkyne
OrC C HH
C C CH3H C C CH(CH3)2H C C RH
Alkynes, CnH2n-‐2
• Di-‐subs)tuted alkyne or internal alkyne • Internal alkyne can be symmetric or asymmetric
C C CH3H3C C C CH(CH3)2(H3C)2HC
C C RR
C C CH(CH3)2H3C C CH3C
C C R'R
Cycloalkynes
Cycloalkyne starts with 8 or more carbons
CyclooctyneCyclodecyne
Arene or Benzene, C6H6
• Unsaturated hydrocarbon
• Planar and non-‐polar molecule
• From high temperature dis)lla)on of coal tar • Hea)ng petroleum at high temperature and pressure over a catalyst
Subs)tuted Benzenes
• Subs)tu)ng one hydrogen from benzene leads to monosubs)tuted arene
• Disubs)tuted benzenes
R
R
R R
R
R
R
1,2-substitutedortho- or o-
1,3-substitutedmeta- or m-
1,4-substitutedpara- or p-
Subs)tuted Benzenes
• Trisubs)tuted benzenes
• Tetrasubs)tuted benzenes
R
R
1,2,3- substituted
R
R
RR
R
R
R
1,2,4- substituted 1,3,5- substituted
R
R
1,2,3,4- substituted
R
R
RR
R
R
R
1,2,4,5- substituted 1,2,3,5- substituted
RR
R
Subs)tuted Benzenes
• Only one possible pentasubs)tuted benzene
• One possible hexasubs)tuted benzene
R
RR
R
R
R
RR
R
RR
Heteroatom-‐subs)tuted Hydrocarbons
R-H R-Groupwhere Group = halogen, OH, SH, NH2, CN
Haloalkanes or Alkyl halides, R-‐X
• Carbon-‐halogen containing molecules • Polar molecule
• R-‐X where X = F, Cl, Br, I R = alkyl or cycloalkyl
ClCl
Classifica)on of Alkyl Halides
• Primary = Halogen is on a primary carbon • Secondary = Halogen is on a secondary carbon • Ter)ary = Halogen is on a ter)ary carbon
Alcohols, R-‐OH
• Carbon bonded to OH group, known as Hydroxyl group
• Polar molecule
• Most alcohols are water insoluble except
Methanol, Ethanol, Propan-‐1-‐ol, Isopropyl alcohol, Butan-‐1-‐ol
H3C OHOH
OH
OH
OH
Classifica)on of Alcohols
• Primary alcohol = OH is on a primary carbon • Secondary alcohol = OH is on a secondary carbon
• Ter)ary alcohol = OH in on a ter)ary carbon
Ethers
Cyclic Ethers
• Oxirane is also known as epoxide
O OO
O O
OxepaneTetrahydro-2H-pyranTetrahydrofuranOxetaneOxirane
O
2-Methyloxirane
O
2,2-Dimethyloxirane
O
3-Ethyl-2,2-dimethyloxirane
Classifica)on of Amines
• The classifica)on depends on how many groups are bonded to N.
• Primary amine = one group bonded to N
• Secondary amine = two groups bonded N
• Ter)ary amine = three groups bonded N
Amines versus Alkyl Halides and Alcohols
Other Nitrogen Containing Compounds, Nitrile
Carbon bonded to cyano group, CN Polar molecule
Nitrile can be reduced to primary amine
Nitrile can be hydrolyzed to carboxylic acid
Nitrile also called carboxylic acid deriva)ve
C C N
Nitrile
C CCH3
CH3H3C N
Pivalonitrile
R C N
Other Nitrogen Containing Compounds,nitro
• Carbon bonded to nitro group • Polar molecule
• Nitro group can be reduced to primary amine
C NO2 C NO2
H
HH
Nitromethane
R NO2
Sulfur Containing Molecoles
• Thiol, R-‐S-‐H • Sulfide, R-‐S-‐R symmetrical and R-‐S-‐R’ asymmetric • Disulfide, R-‐S-‐S-‐R symmetric and R-‐S-‐S-‐R’ asymmetric • Sulfonium salt, R3S+X-‐
• Sulfide oxidezes to Sulfoxide and to Sulfone
SO
R R
Sulfoxide
SO
OR R
Sulfone
Carbonyl Family
• Aldehydes and Ketones • Carbonyl compounds with hydrogen and alkyl groups • Formaldehyde: two hydrogen
• Aldehyde: a hydrogen and an alkyl group • Ketone: two alkyl groups
Aldehydes and Ketones Found in Nature
Biologically Important Ketones
Carboxylic Acid and Deriva)ves
A Carbonyl Group and An Acyl Group
Carboxylic Acids
• Carbon bonded to CO2H group, known as carboxyl group
• Polar molecule
• Weak acids, pKa ~5
C CO2H R CO2HR
O
OH
Carboxylic Acids
Carboxylate Ion Salts
• Conjugate base of carboxylic acid is known as salt of carboxylic acid
Carboxylic Acid Deriva)ve, Ester
• Most esters have pleasant odor • Esters can be obtained from carboxylic acids
• Polar molecule
R
O
OR'
O
O
Ethyl acetate
O
O
Ethyl cyclohexanecarboxylate
O
O
Ethyl benzoateEster
Cyclic Esters, Lactones
Carboxylic Acid Deriva)ve, Amide
Amide are classified as Primary, Secondary and Ter)ary
R
O
NH2
Primary Amide
R
O
NHR'
Secondary Amide
R
O
NR2'
Tertiary Amide
Amide
Cyclic Amides, Lactams
Carboxylic Acid Deriva)ve, Acid Halide
Carboxylic Acid Deriva)ve, Anhydride
• Anhydride can be symmetric or asymmetric
• Anhydride can be cyclic
R
O
O R
O
symmetirc anhydride
O
O
O O
O
O
Acetic anhydride Benzoic anhydrideO
O
O
R
O
O R'
O
asymmetirc anhydride Acetic benzoic anhydride
O
O
O
Decahydro-1H-benzo[c]oxecine-1,3(4H)-dione
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