CHEM 109A Organic Chemistry

Home , Alkyl, Butyl group, Ethyl group, Functional group, Pentyl group, Propyl group

2/2/18

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

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 branched cyclic (CnH2n+2) (C H ) n 2n+2 (CnH2n)

hexane cyclohexane

butane

Alkanes and Alkyl Groups:

Two alkanes C4H10 CH3CH2CH2CH2−X X Butane n-Butyl group and X X CH3CH2CH2CH3

CH3CH2CHCH2 Butane sec-butyl group

and Isobutane X CH3CH(CH3)2 X and CH3 (CH3)3C−X CH3 CH (CH3)2CHCH2−X CH3 Isobutane isobutyl group tert-butyl group

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Alkyl Substituents

X X X X

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

R X

generic alkyl group

n = an Unbranched Chain

Common names sometimes use “n” (stands for “normal”) to indicate a straight-chain alkane.

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Alkyl Substituents

X X X X

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

X R X X

Primary, Secondary, and Tertiary Carbons

• A primary carbon is bonded to one carbon. • A secondary carbon is bonded to two carbons. • A tertiary carbon is bonded to three carbons.

• Primary hydrogens are attached to primary carbons. • Secondary hydrogens are attached to secondary carbons. • Tertiary hydrogens are attached to tertiary carbons.

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Common Types of Organic Compounds

R N R R O R X R OH R NH2 H R R N X = F, or Cl, or Br, or I R R

an alkyl halide an alcohol an ether an alkyl amine

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

A name must specify only one compound.

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

tert-hexyl is not a good name.

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“Iso”

Iso is at one end, and the group replacing the H is at the other end.

Alkyl Group Names

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

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Nomenclature of Alkanes

First identify the longest continuous chain (the parent hydrocarbon)

Add the Name of the Substituent

Number the chain in the direction that gives the substituent as low a number as possible.

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Common versus Systematic Nomenclature

Common names never have numbers. Only systematic names have numbers.

List Substituents in Alphabetical Order

The correct name is the one that contains the lowest number.

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Multiple Substituents

The chain is numbered in the direction that puts the lowest number in the name. Substituents are listed in alphabetical order. (di, tri, tetra, sec, tert are not alphabetized)

When Both Have the Same Lowest Number

When both names have the same lowest number, go for the next lowest number.

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When Both Have the Same Numbers

When the same numbers are obtained in both directions, the first group listed gets the lower number.

Branched Substituents

If the substituent has a common name, the common name can be used instead of the parenthetical name.

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Branched Substituents

If the substituent does not have a common name, the parenthetical name has to be used.

Chains with the Same Length

When two or more chains have the same length, the parent hydrocarbon is the chain with the most substituents.

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Cycloalkanes

Skeletal structures do not show Cs and Hs bonded to Cs.

Monosubstituted Cycloalkanes

A number is not needed.

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Disubstituted Cycloalkanes

• substituents are stated in alphabetical order. • #1 goes to the first-listed substituent.

Two Substituents with the Same Low Number

• choose lowest numbers

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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

Common: Alkyl Halide ( isopropyl bromide, n-butyl fluoride)

Systematic: normal rules, halogen substituents are F: fluoro- Cl: chloro- Br: bromo- I: iodo-

(Fun fact: Numbers are used only for systematic names. Common names never have numbers.)

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Nomenclature of Alkyl Halides

F F I F

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Ethers

O O R R R R'

same different

Common Names of Ethers

The substituents are listed in alphabetical order.

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Systematic Names of Ethers

O O O O O

F O Br

Classification of Alcohols

HO HO OH OH

primary alcohol = OH is on a primary carbon secondary alcohol = OH is on a secondary carbon tertiary alcohol = OH in on a tertiary carbon

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Classification of Alcohols

HO HO OH OH

primary alcohol = OH is on a primary carbon secondary alcohol = OH is on a secondary carbon tertiary alcohol = OH in on a tertiary carbon

Common Names of Alcohols

OH OH

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Systematic Names of Alcohols

• Use “-ol” as a suffix to denote OH, alcohol • The OH is the “functional group.” • Alcohols are named by replacing the “e” at the end of the parent hydrocarbon with the suffix “ol.”

(methane) (ethane)

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

When there is both a functional group and a substituent, the functional group gets the lowest number.

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Nomenclature of Alcohols

The parent hydrocarbon is the longest chain that contains the functional group.

Number the chain in the direction that gives the functional group the lowest possible number.

Nomenclature of Alcohols

If you get the same number for the functional group in both directions, chose the direction that gives a substituent the lowest number.

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Nomenclature of Alcohols

OMe F

If there is more than one substituent, listed them in alphabetical order.

A Substituent is a Prefix A Functional Group is a Suffix

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Classification of Amines

The classification depends on how many groups (R) are bonded to the N.

primary amine = one group bonded to the N secondary amine = two groups bonded to the N tertiary amine = three groups bonded to the N

Classification of Amines versus Alkyl Halides and Alcohols

(tertiary alkyl amine)

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Common Names of Amines

Substituents are listed in alphabetical order followed by “amine.” They are written as one word.

Systematic Names of Amines

The suffix “amine” denotes the amine functional group. The “e” at the end of the alkane name is replaced by “amine.”

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Nomenclature of Amines

A substituent on the chain is indicated by a number. A substituent on the nitrogen is indicated by an “N.”

Nomenclature of Amines

List substituents in alphabetical order, then add a number or N.

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Quaternary Ammonium Salts

When there are four groups bonded to the N, the groups are stated in alphabetical order followed by “ammonium” and then the name of the anion.

Summary of Nomenclature