03 03 Lecture 02 02 2018 - UCSB2. number the carbons – start with the end closest to a substituent or branching point 3. properly name the substituent alkyl groups : name the group,

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© 2017 Pearson Education, Inc.

https://labs.chem.ucsb.edu/zakarian/armen/courses.html

CHEM 109A Organic Chemistry

Chapter 3 An Introduction to Organic Compounds

Nomenclature, Physical Properties, and Structure


MIDTERM 1 INFORMATION

Feb. 5, Monday Location If last name starts with A - S: room BUCHN 1910 (this room) T - Z: room PHELPS 1508 covering Chapter 1, 2, 3 (3.1 – 3.8)

also, no class on Wednesday, Feb. 7

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Types of Alkanes in Chapter 3

straight chain (CnH2n+2)

branched (CnH2n+2)

cyclic (CnH2n)

cyclohexane hexane

butane


Alkanes and Alkyl Groups: Two alkanes C4H10

CH3CH2CH2CH3

Butane

CH3CH2CH2CH2−X

n-Butyl group

and Isobutane

CH3CH(CH3)2

Isobutane

(CH3)3C−X

tert-butyl group

Butane

and

CH3CH2CHCH2

sec-butyl group

X

X

X

CH3 CHCH3

CH3

XX

and

(CH3)2CHCH2−X

isobutyl group

butane and isobutane are constitutional isomers

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Alkyl Substituents

X

ethyl group

X

X X

n-propyl group n-butyl group n-pentyl group

R X

generic alkyl group


n = an Unbranched Chain

Commonnamessometimesuse“n”(standsfor“normal”)toindicateastraight-chainalkane.

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Alkyl Substituents

X

ethyl group

X

X X

n-propyl group n-butyl group n-pentyl group

R X

generic alkyl groupsec-butyl group

X X

isobutyl group

branched alkyl groups


Primary, Secondary, and Tertiary Carbons

•  Aprimarycarbonisbondedtoonecarbon.

•  Asecondarycarbonisbondedtotwocarbons.•  Atertiarycarbonisbondedtothreecarbons.

• Primaryhydrogensareattachedtoprimarycarbons.

• Secondaryhydrogensareattachedtosecondarycarbons.

• Tertiaryhydrogensareattachedtotertiarycarbons.

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Common Types of Organic Compounds

ROR X R OH R NH2

X = F, or Cl, or Br, or I

an alkyl halide an alcohol an ether an alkyl amine

RR

HN

R

RN

R

R


Nomenclature: Systematic and Common

Summary of basic rules for systematic nomenclature: 1. find the longest carbon chain: that is your root (8 carbons? - octane....) 2. number the carbons – start with the end closest to a substituent or branching point 3. properly name the substituent

alkyl groups: name the group, goes in front as prefix, alphabetical order halides: fluoro-, chloro-, bromo-, iodo-, if more than 1, di(bromo)-, tri-, tetra-, etc. also go in front, alphabetical order HO groups: back of the name (suffix), -ol (like methanol); if more than one, -diol, -triol, -tetraol..... RO groups: called alkoxy- (methoxy, ethoxy, etc.) go in front NH2 groups: go in the back as -amine (1-butanamine)

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sec-Pentyl is Not a Good Name

Anamemustspecifyonlyonecompound.


“tert” Can Be Used with “Butyl” and “Pentyl”

tert-hexylisnotagoodname.

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“Iso”

Isoisatoneend,andthegroupreplacingtheHisattheotherend.


Alkyl Group Names

iso-, sec-, tert- : to be used with common names only

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Nomenclature of Alkanes

Firstidentifythelongestcontinuouschain

(theparenthydrocarbon)


Add the Name of the Substituent

Numberthechaininthedirectionthatgivesthesubstituentaslowanumberaspossible.

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Common versus Systematic Nomenclature

Commonnamesneverhavenumbers.Onlysystematicnameshavenumbers.


List Substituents in Alphabetical Order

Thecorrectnameistheonethatcontainsthelowestnumber.

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Multiple Substituents

Thechainisnumberedinthedirectionthatputsthelowestnumberinthename.

Substituentsarelistedinalphabeticalorder.(di,tri,tetra,sec,tertarenotalphabetized)


When Both Have the Same Lowest Number

Whenbothnameshavethesamelowestnumber,goforthenextlowestnumber.

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When Both Have the Same Numbers

Whenthesamenumbersareobtainedinbothdirections,thefirstgrouplistedgetsthelowernumber.


Branched Substituents

Ifthesubstituenthasacommonname,thecommonnamecanbeusedinsteadoftheparentheticalname.

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Branched Substituents

Ifthesubstituentdoesnothaveacommonname,theparentheticalnamehastobeused.


Chains with the Same Length

Whentwoormorechainshavethesamelength,theparenthydrocarbonisthechainwiththemostsubstituents.

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Cycloalkanes

SkeletalstructuresdonotshowCsandHsbondedtoCs.


Monosubstituted Cycloalkanes

Anumberisnotneeded.

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Disubstituted Cycloalkanes

•  substituentsarestatedinalphabeticalorder.•  #1goestothefirst-listedsubstituent.


Two Substituents with the Same Low Number

•  chooselowestnumbers

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Classification of Alkyl Halides

primary alkyl halide = halogen is on a primary carbon secondary alkyl halide = halogen is on a secondary carbon tertiary alkyl halide = halogen is on a tertiary carbon


Alkyl Halides: Common versus Systematic Nomenclature

(Funfact:Numbersareusedonlyforsystematicnames.

Commonnamesneverhavenumbers.)

Common: Alkyl Halide ( isopropyl bromide, n-butyl fluoride) Systematic: normal rules, halogen substituents are

F: fluoro- Cl: chloro- Br: bromo- I: iodo-

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Nomenclature of Alkyl Halides


Nomenclature of Alkyl Halides

F F

FI

Br

Br

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Ethers

RO

R RO

R'

same different


Common Names of Ethers

Thesubstituentsarelistedinalphabeticalorder.

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Systematic Names of Ethers

OO O O O

OFBr


Classification of Alcohols

primaryalcohol=OHisonaprimarycarbonsecondaryalcohol=OHisonasecondarycarbon

tertiaryalcohol=OHinonatertiarycarbon

OHOHHO

HO

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Classification of Alcohols

primaryalcohol=OHisonaprimarycarbonsecondaryalcohol=OHisonasecondarycarbon

tertiaryalcohol=OHinonatertiarycarbon

OHOHHO

HO


Common Names of Alcohols

OH OH

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Systematic Names of Alcohols

•  Use“-ol”asasuffixtodenoteOH,alcohol•  The OH is the “functional group.”•  Alcoholsarenamedbyreplacingthe“e”attheendoftheparent

hydrocarbonwiththesuffix“ol.”

(ethane) (methane)


Systematic Names of Alcohols

•  When selecting the chain, and numbering it, OH has the priority

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Compounds with Two OH Groups: diol


Nomenclature of Alcohols

Whenthereisbothafunctionalgroupandasubstituent,thefunctionalgroupgetsthelowestnumber.

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Theparenthydrocarbonisthelongestchain thatcontainsthefunctionalgroup.

Numberthechaininthedirectionthatgives

thefunctionalgroupthelowestpossiblenumber.



Ifyougetthesamenumberforthefunctionalgroupinbothdirections,

chosethedirectionthatgivesasubstituentthelowestnumber.

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Ifthereismorethanonesubstituent,listedtheminalphabeticalorder.

FOMe


A Substituent is a Prefix A Functional Group is a Suffix

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Classification of Amines

Theclassificationdependsonhowmanygroups(R)arebondedtotheN.

primaryamine =onegroupbondedtotheN

secondaryamine=twogroupsbondedtotheN

tertiaryamine=threegroupsbondedtotheN


Classification of Amines versus Alkyl Halides and Alcohols

(tertiary alkyl amine)

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Common Names of Amines

Substituentsarelistedinalphabeticalorderfollowedby“amine.”

Theyarewrittenasoneword.


Systematic Names of Amines

Thesuffix“amine”denotestheaminefunctionalgroup.The“e”attheendofthealkanenameisreplacedby“amine.”

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Nomenclature of Amines

Asubstituentonthechainisindicatedbyanumber.Asubstituentonthenitrogenisindicatedbyan“N.”


Nomenclature of Amines

Listsubstituentsinalphabeticalorder,thenaddanumberorN.

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Quaternary Ammonium Salts

WhentherearefourgroupsbondedtotheN,thegroupsarestatedinalphabeticalorderfollowedby“ammonium”andthenthenameoftheanion.


Summary of Nomenclature

Documents

03 03 Lecture 02 02 2018 - UCSB2. number the carbons – start with the end closest to a substituent or branching point 3. properly name the substituent alkyl groups : name the group,