oc1 chapter 4 nomenclature (1)

7/23/2019 OC1 Chapter 4 Nomenclature (1)

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Chapter 4 - Nomenclature

By Todd Rothman

Copyright 2013

I. Alkane Nomenclature ............................................. 02

II. Cycloalkane and Bicycloalkane nomenclature ...... 10

III. Functional Group Nomenclature ......................... 14


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I. Alkane Nomenclature

1. Unbranched nomenclature

# of carbons formula IUPAC Name

1 CH4

methane

2 CH3CH

3ethane

3 CH3CH

2CH

3propane

4 CH3CH

2CH

2CH

3butane

5 CH3CH

2CH

2CH

2CH

3pentane

6 CH3CH

2CH

2CH

2CH

2CH

3hexane

7 CH3CH

2CH

2CH

2CH

2CH

2CH

3heptane

8 CH3CH

2CH

2CH

2CH

2CH

2CH

2CH

3octane

9 CH3CH

2CH

2CH

2CH

2CH

2CH

2CH

2CH

3nonane

10 CH3CH

2CH

2CH

2CH

2CH

2CH

2CH

2CH

2CH

3decane

2 types of nomeclature rules:

- International Union of Pure and Applied Chemistry (IUPAC)

systematic method for determining the name of a molecule

- Common Nomenclature

either semisystematic or unsystematic. Often the name is derived from the source of the compound

example:Formic acid comes from formica which is latin for ant, where this acid is found.

Organic Chemistry 1 - Nomenclature

Copyright 2013 - By Todd Rothman


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2. branched alkane nomenclature

General Nomenclature Rules:

Step 1. Find the parent carbon chain

Step 2. Number the atoms in the parent carbon chain

Step 3. Determine the name and number of the substituents

Step 4. Put the name together

Substituents - any branching groups off the parent carbon chain

How to name alkane substituents:

remove the "ane" from the end of the alkane name and add "yl"

methane --> methyl

ethane --> ethyl

propane --> propyl

butane --> butyl

pentane --> pentyl

hexane --> hexyl

heptane --> heptyl

octane --> octyl

nonane --> nonyl

decane --> decyl

Halogens are easy to name solets add them to our list:

Rule:

remove the "ine" from the end of

the halogen name and add "o"

(F) fluorine --> fluoro

(Cl) chlorine --> chloro

(Br) bromine --> bromo

(I) iodine --> iodo




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Step 1 - Find the Parent carbon chain

Find the longest continuous chain of carbons. you must start from 1 end of the moleculeto the other. It does not have to be a straight line across:

If you have 2 or more ways to get the same number of continuous carbons, then use thepath with the most branching:

Br




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Step 2 - Number the atoms in the carbon chain to find the parent chain

If the first substituent is the same distance for both ends, then give the secondsubstituent the lowest possible number. Repeat this until there is a difference

first substituent should have the lowest number

If you can number both ends and get the same low numbers then go with alphabetical prioirty

substituent = branch

Br




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Step 3. Determine the name and number of the substituents

- use the numbers from the previous step to designate their location

- if 2 or more are the same substituent use the prefix di, tri, tetra, penta, hexa)

Br




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Step 4 - Put the name together

#-substitutent + parent

- numbers are separated by commas

- numbers and letters are separated by hyphens

- each substituent must have its own number even if it is the same or on the same carbon

- alphabetize the names of the substituents to determine the order. Ignore all prefixesexcept iso

Br




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3. Common names for complex substituents

a. iso unit

parent

parent

iso can be larger than 3 carbons, for example:

isopropyl isobutyl

parent

isopentyl

b. butyl units

parent

parent

butyl (normal)

n-butyl

sec-butyl

parent

note: parent refers to the parent that

these substituents are bonded to

tert-butyl

c. neo unit

parent

neopentyl

Sometimes the substituents will not be a straight chain of carbons. Fortunately, there areseveral common names that we can learn to name these complex branches.

d. other common names to remember

parent parent

allyl vinyl




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Examples of complex substituent nomenclature

Cl

Cl

a.

b.

c.




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II. Cyclo & Bicyclo Nomenclature

1. Cycloalkanes, cycloalkenes, and cycloalkynes

Substituent + Prefix + infix + suffix

Substituents - all branches off the parent chain.

branches include alkyl groups and halides

all substituents must have a number to identify it's location

we use di, tri, tetra, penta to emphasize the same group

Prefix - start with cyclo then add meth, eth, prop, but, pent, hex, hept, oct, non, dec

infix - an , en, yn

- en and yn need a number to tell us where the d-bond or t-bond begins

- The number can come before the prefix or before the infix

- The d-bond or t-bond has the highest prioirty for hydrocarbons. So it must be #1 & 2

suffix - add an "e" to the end of the name.

(Note: when we learn about naming functional groups, we will see many more suffix names. This is why we seperate infix from suffix.)

General Rules-

- when organizing the name it is based on alphabetical priority and not numerical priority

- The prefixes (di, tri, tert, sec, neo) are ignored when alphabetizing except for iso

- if there is only 1 substituent off the ring then you do not need to site the position. It is always assumed to be position 1

- if there is more than 1 substituent, begin numbering at one of the substituents and continue clockwise or counterclockwise to get the next substituent the second lowest number

- if only 2 substituents assign the first postion to the substituent that has alphabetical prioirty

- never name the compound a parent that includes the ring and straight chain. It is either a ring as the parent or a chain as the parent

- if the number of carbons in the ring is equal or greater than the number of carbons in the straight chain, the parent is a ring

PARENT CHAIN




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BrBr

Examples:

Br

Br

Cl

Cl

a. b.

d. e.

f. g.

c.




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2. Bicycloalkane nomenclature

bicyclo[x.y.z]parent

bicyclo - all fused ring systems begin their name with a reference to the number of rings

(bicyclo = 2 rings tricyclo = 3 rings tetracyclo = 4 rings)

xyz - this tells us the number of carbons for each side of the ring. All bicyclo rings have 3 sides even if one side has no carbons. The circled red represent bridge carbons. These are carbons that connect all ring sides together. We do not include the red carbons when numbering the sides of the ring.

parent - This is the full name of the cyclic system. this name is derived from the total

number of carbons in the ring (including the bridge carbons)

bicyclo not bicyclo tricyclo

(must be fused)

4.4.0 4.4.1 3.2.1

bicyclo[4.4.0]decane bicyclo[4.4.1]undecane bicyclo[3.2.1]octane




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Bicycloalkane nomenclature examples

Cl

Cl

Br

a. b.

c. d.

e.

Br

Cl

f.




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suffix - functional group reference (has a number to tell us where it is unless C1)

COOH = oic acid

aldehyde = al

ketone = one

OH = ol

N = amine

alkane, alkene, alkyne - e

Substituent + Prefix + infix + suffix

Substituents - all branches off the parent chain.

branches include alkyl groups and halides

all substituents must have a number to identify it's location

we use di, tri, tetra, penta to emphasize the same group

Prefix - meth, eth, prop, but, pent, hex, hept, oct, non, dec

infix - an , en, yn

- en and yn need a number to tell us where it begins

- The number can come before the prefix or before the infix

Suffix has the highest priority whennaming structures. The functionalgroup that makes up the suffix portionof the name must have the lowestpossible number when numbering theparent chain. So whichever end isclosest to the functional group isnumber 1

priority

General Rules-

- when organizing the name it is based on alphabetical prioirty and not numerical priority

- all prefixes (di, tri, tert, sec, neo, etc.) are ignored when alphabetizing except for iso.

- if there is a substituent attached to Nitrogen of an amine or amide we identify it by writing a capital N instead of a number. In this context, "N" is treated like a number

PARENT CHAIN

General Nomenclature Rules Including Some Functional Groups

III. Functional Group Nomenclature




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Functional group nomenclature examples

Amines

NH N Br

Br

Alcohols

OH

OH

OH

Br

Cl

N Cl

OH

OH




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Functional group nomenclature examples

ketones, aldehydes, and carboxylic acids

O O Br

O

Cl

O

Cl OH

O

Br

Br

O

OH



oc1 chapter 4 nomenclature (1)

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