Nomenclature Common: named as if derived from hydrogen halide, HX - - PowerPoint PPT Presentation

Nomenclature Common: named as if derived from hydrogen halide, H–X

Nomenclature Common: named as if derived from hydrogen halide, H–X CH3–Cl methyl chloride

Br

Nomenclature Common: named as if derived from hydrogen halide, H–X CH3–Cl methyl chloride (CH3)2CH–Br isopropyl bromide

Br

Nomenclature Common: named as if derived from hydrogen halide, H–X CH3–Cl methyl chloride (CH3)2CH–Br isopropyl bromide R–X alkyl halide

Br

Nomenclature Common: named as if derived from hydrogen halide, H–X CH3–Cl methyl chloride (CH3)2CH–Br isopropyl bromide R–X alkyl halide grouped into 1, 2, 3 classes based on identity of R

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane

F

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane

F

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane 3-fluoroheptane

F F

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane 3-fluoroheptane

F F

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane 3-fluoroheptane (S)-3-fluoroheptane

F F Br Br Cl

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane 3-fluoroheptane (S)-3-fluoroheptane

F F Br Br Cl

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane 3-fluoroheptane (S)-3-fluoroheptane (Z)-5,5-dibromo-2-chloro-2-hexene

F F Br Br Cl Br

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane 3-fluoroheptane (S)-3-fluoroheptane (Z)-5,5-dibromo-2-chloro-2-hexene

F F Br Br Cl Br

Nomenclature IUPAC: named as substituted alkanes substituent name for X is halo R–X haloalkane 3-fluoroheptane (S)-3-fluoroheptane (Z)-5,5-dibromo-2-chloro-2-hexene (1R,3S)-1-bromo-3-methylcyclohexane

Some essential properties of haloalkanes

• R–X are polar

C X H H H δ+ δ−

Some essential properties of haloalkanes

• R–X are polar
• the C of C–X is intrinsically electrophilic. This dominates the chemistry of this functional group

C X H H H δ+ δ−

Some essential properties of haloalkanes

• R–X are polar
• the C of C–X is intrinsically electrophilic. This dominates the chemistry of this functional group
• R–X have bp’s higher than corresponding R–H

bp - 0.5 C bp 79 C

C X H H H δ+ δ−

Cl

Some essential properties of haloalkanes

• R–X are polar
• the C of C–X is intrinsically electrophilic. This dominates the chemistry of this functional group
• R–X have bp’s higher than corresponding R–H

bp - 0.5 C bp 79 C

• R–X are toxic

C X H H H δ+ δ−

Cl

Some essential properties of haloalkanes

• R–X are polar
• the C of C–X is intrinsically electrophilic. This dominates the chemistry of this functional group
• R–X have bp’s higher than corresponding R–H

bp - 0.5 C bp 79 C

• R–X are toxic
• R–X are relatively rare as natural products

C X H H H δ+ δ−

Cl

Cl Cl Cl Cl Cl OCH3 Cl Cl Cl O H CH3 O O Cl Cl OSO3 Cl OH Cl Cl Cl Cl OH Cl OH Cl Cl Cl OH OH

• Synthetic and Naturally Occurring Haloalkanes

DDT (insecticide) methyl ether of a trichloroorcinol LD50 = 115 mg/kg (fungicide produced by water lillies) cytotoxic sulfolipid from Mytilus galloprovincialis IC50 = 13 M

Cl Cl Cl Cl Cl OCH3 Cl Cl Cl O H CH3 O O Cl Cl OSO3 Cl OH Cl Cl Cl Cl OH Cl OH Cl Cl Cl OH OH

• Synthetic and Naturally Occurring Haloalkanes

DDT (insecticide) methyl ether of a trichloroorcinol LD50 = 115 mg/kg (fungicide produced by water lillies) (compare LD50 acetaminophen = 338 mg/kg) cytotoxic sulfolipid from Mytilus galloprovincialis IC50 = 13 M

O O OH OH Cl O Cl O H HO OH Cl

O O OH OH OH O O H HO OH OH O H

sucralose (Splenda™) 400-800 times as sweet as sugar sucrose

Hey! How about a bit of review: How many chiral centers does Splenda have?

O O OH OH Cl O Cl O H HO OH Cl

How many chiral centers does Splenda have?

O O OH OH Cl O Cl O H HO OH Cl * * * * * * * * *

How many chiral centers does Splenda have? nine What is the theoretical maximum number of stereoisomers can this sugar substitute have?

O O OH OH Cl O Cl O H HO OH Cl

How many chiral centers does Splenda have? nine What is the theoretical maximum number of stereoisomers can this sugar substitute have? 2n , where n = number of stereogenic groups: 29 = 512

O O OH OH Cl O Cl O H HO OH Cl

Are the configurations of Splenda’s indicated chiral centers R or S? O O OH OH Cl O Cl O H HO OH Cl

Are the configurations of Splenda’s indicated chiral centers R or S?

O O OH OH Cl O Cl O H HO OH Cl Cl H C C O C H O H C C O C O C C O O Cl

R

1 2 3 4 3 2 4 1

R

C C C C C Hb Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Hc Hc Hd Hd Hd Cl Ha Ha Ha Ha Ha Cl2 ∆

Product distribution studies of the radical chlorination of 2-methylbutane Hydrogens (or any functional groups) that produce the same product are said to be chemically equivalent or homotopic Substitution of any 1 of the six Ha results in 1-chloro-2-methybutane 2-methylbutane has a group of six chemically equivalent Ha hydrogens Another way of describing this: both of the CHa3 methyl groups are chemically equivalent 2-(fun)butane

C C C C C Hb Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C (fun) C Hb Hc Hc Hd Hd Hd Ha Ha Ha ∆ substituion of CH3 groups by (fun) groups

C C C C C Hb Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Hc Hc Hd Hd Hd Cl Ha Ha Ha Ha Ha C C C C C Cl Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha Cl2 ∆

Substitution of the Hb results in 2-chloro-2-methylbutane 2-methylbutane has a group of one chemically equivalent Hb hydrogen The Ha’s and Hb are not chemically equivalent Chemically nonequivalent functional groups are heterotopic functional groups 1-chloro-2-methylbutane

C C C C C Hb Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Hc Hc Hd Hd Hd Cl Ha Ha Ha Ha Ha C C C C C Cl Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Cl Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Hc Cl Hd Hd Hd Ha Ha Ha Ha Ha Ha Cl2 ∆

Substitution of an Hc results in (R)-2-chloro-3-methylbutane or (S)-2-chloro-3-methylbutane (a racemate) 2-methylbutane has a group of two chemically equivalent Hc hydrogens The Hc’s generate stereoisomers upon substititution These stereoisomers are enantiomers Functional groups that make stereoisomeric products are stereotopic groups If these stereoisomers are enantiomers, the functional groups are enantiotopic 1-chloro-2-methylbutane 2-chloro-2-methylbutane

C C C C C Hb Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Hc Hc Hd Hd Hd Cl Ha Ha Ha Ha Ha C C C C C Cl Hc Hc Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Hc Cl Hd Hd Hd Ha Ha Ha Ha Ha Ha C C C C C Hb Hc Hc Cl Hd Hd Ha Ha Ha Ha Ha Ha Cl2 ∆

Substitution of an Hd results in 1-chloro-3-methylbutane 2-methylbutane has a group of three chemically equivalent Hd hydrogens The CHa3 methyl groups and the CHd3 methyl group are not chemically equivalent So, 2-methylbutane has four groups of chemically nonequivalent hydrogens 1-chloro-2-methylbutane 2-chloro-2-methylbutane rac-2-chloro-3-methylbutane

C C C C Hb Hc Hc Hd Hd Hd Ha Ha Ha F C C C C Hb Cl Hc Hd Hd Hd Ha Ha Ha F C C C C Hb Hc Cl Hd Hd Hd Ha Ha Ha F Cl2 ∆

What if a substitution resulted in diastereoisomeric products? (S)-2-fluorobutane (2S,3S)-2-chloro-3-fluorobutane (2R,3S)-2-chloro-3-fluorobutane (S)-2-fluorobutane has two chemically nonequivalent Hc hydrogens The Hc’s generate stereoisomers upon substititution These stereoisomers are diasteriomers Functional groups that make stereoisomeric products are stereotopic groups If these stereoisomers are diasteriomers, the functional groups are diastereotopic So, (S)-2-fluorobutane has five chemically nonequivaent groups of hydrogens

Types of groups of hydrogens Chemically equivalent Chemically nonequivalent (homotopic) (heterotopic) generate the same constitutional generate different constitutiona isomer upon substitution isomers upon substitution generate enantiomers upon generate diastereomers upon substitution (enantiotopic) substitution (diastereotopic)