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Introduc)on to Func)onal Groups in Organic Molecules O
H3C
CH3
C
N
C
N
CH
C
O
C
N
CH3
Caffeine
N
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. Condensed Structures of Alkanes • 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 and Line Structures • Condensed structure of Butane • Line structure of Butane Cycloalkanes, CnH2n Bond Angles in Planar Cyclic Alkanes Alkenes -­‐ Hydrocarbon With Carbon-­‐
Carbon Double Bond • • • • • 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 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 H
H
H
CH3
H
R
H
H
H
H
H
H
Ethene
Propene
Monosubstitued alkene
• Disubs)tuted alkenes can be classified as R
H
R
H
R
R
R
H
H
R
H
H
Geminal
trans
cis
Classifica)on of Alkenes • Trisubs)tuted alkene R
R
H
R
• Tetrasubs)tued alkene R
R
R
R
Cycloalkenes, CnH2n-­‐2 Cyclopropene
Cycloheptene
Cyclobutene
Cyclooctene
Cyclopenten
Cyclohexene
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 H C C H
Or
• Mono-­‐subs)tuted alkyne or terminal alkyne H C C CH3
H C C CH(CH3)2
H C C R
Alkynes, CnH2n-­‐2 • Di-­‐subs)tuted alkyne or internal alkyne • Internal alkyne can be symmetric or asymmetric (H3C)2HC C C CH(CH3)2
H3C C C CH3
R
H3C
C
C
C
C R
H3C
CH(CH3)2
R
C
C
R'
C
C
Cycloalkynes Cycloalkyne starts with 8 or more carbons Cyclooctyne
Cyclodecyne
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 R
• Disubs)tuted benzenes R
R
R
R
R
R
1,2-substituted
ortho- or o-
1,3-substituted
meta- or m-
1,4-substituted
para- or p-
Subs)tuted Benzenes • Trisubs)tuted benzenes R
R
R
R
R
R
R
R
R
1,2,3- substituted
1,2,4- substituted
1,3,5- substituted
• Tetrasubs)tuted benzenes R
R
R
R
1,2,3,4- substituted
R
R
R
R
1,2,4,5- substituted
R
R
R
R
1,2,3,5- substituted
Subs)tuted Benzenes • Only one possible pentasubs)tuted benzene R
R
R
R
R
• One possible hexasubs)tuted benzene R
R
R
R
R
R
Heteroatom-­‐subs)tuted Hydrocarbons R-H
R-Group
where 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 Cl
Cl
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 OH
H3C
OH
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 O
O
O
O
Tetrahydro-2H-pyran
Oxepane
O
Oxetane
Oxirane
Tetrahydrofuran
• Oxirane is also known as epoxide 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
CH3
H3C C C N
CH3
Pivalonitrile
R C N
Other Nitrogen Containing Compounds,nitro • Carbon bonded to nitro group • Polar molecule • Nitro group can be reduced to primary amine H
C NO2
H C NO2
H
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 O
R
S
O
R
Sulfoxide
R
S
O
Sulfone
R
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 O
C
CO2H
R
CO2H
R
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 O
R
O
OR'
Ester
O
O
O
Ethyl acetate
O
Ethyl cyclohexanecarboxylate
O
Ethyl benzoate
Cyclic Esters, Lactones Carboxylic Acid Deriva)ve, Amide Amide are classified as Primary, Secondary and Ter)ary O
R
O
O
NH2
Primary Amide
R
NHR'
Secondary Amide
R
NR2'
Tertiary Amide
Amide Cyclic Amides, Lactams Carboxylic Acid Deriva)ve, Acid Halide Carboxylic Acid Deriva)ve, Anhydride • Anhydride can be symmetric or asymmetric O
R
O
O
O
O
R
O
Acetic anhydride
Benzoic anhydride
O
O
O
O
O
R
symmetirc anhydride
O
O
O
R'
asymmetirc anhydride
O
Acetic benzoic anhydride
• Anhydride can be cyclic O
O
O
Decahydro-1H-benzo[c]oxecine-1,3(4H)-dione