Description
This article is from the Chemistry
FAQ, by Bruce Hamilton B.Hamilton@irl.cri.nz with numerous
contributions by others.
12.4 How can I get the IUPAC chemical name from traditional names?
It depends. Usually the quickest way is to look the name up in a chemical
supplier's catalog, MSDS, or a standard text like Merck or Hawley. You can
also often find the correct name if you refer to an old chemistry text that
lists both the traditional and IUPAC naming conventions. Some traditional
or common names also refer to mixtures of chemicals, eg aqua regia, piranha
solution.
One reason why traditional names have been replaced is because the same name
could be used for different compounds. An example is the use of caprylic to
describe 1-Octanol and 2-Octanol, and attempts to qualify the name with
"primary" and "secondary" were less than successful. Octyl alcohol has been
used to describe both 1-octanol and 2-ethylhexanol, thus explaining why the
well known dioctyl phthalate (DOP) is actually bis(2-ethylhexyl) phthalate.
The following examples highlight the diversity of names often encountered.
Carbon Alkane Alcohol Aldehyde Acid
1 methane methanol form- formic
carbinol
2 ethane ethyl acet- acetic
methyl carbinol
3 n-propane n-propyl propion- propionic
ethyl carbinol
4 n-butane n-butyl n-butyr- n-butyric
propyl carbinol
5 n-pentane n-amyl n-valer- n-valeric
butyl carbinol
6 n-hexane hexyl capro- caproic
amyl carbinol caproic
7 n-heptane enanthyl enanth- enanthic
enanthic
hexyl carbinol
8a n-octane capryl capryl- caprylic
primary caprylic caprylic
heptyl carbinol
1-octanol
8b capryl
secondary caprylic
methyl hexyl carbinol
2-octanol
9 n-nonane pelargonic pelargonic pelargonic
octyl carbinol
10 n-decane capric capr- capric
nonyl carbinol capric
12 n-dodecane lauryl laur- lauric
lauric lauryl
14 n-tetradecane myristyl myrist- myristic
16 n-hexadecane cetyl palmit- palmitic
cetane
18 n-octadecane stearyl stearic
20 n-eicosane arachidyl arachidic
Primary
- alcohol R1CH2OH
- amine R1NH2
eg normal straight chain normal octane n-octane
normal butanol 1-butanol
iso branched chain iso-butane 2-methylpropane
iso-butanol 2-methyl-1-propanol
iso-octane 2,2,4-trimethylpentane
Secondary
- alcohol R1R2CHOH
- amine R1R2NH
eg sec-butanol 2-butanol
iso-propanol 2-propanol
Tertiary
- alcohol R1R2R3COH
- amine R1R2R3N
eg tert-butanol 2-methyl-2-propanol
- substitution onto the benzene ring
1,2 = ortho ortho-xylene
1,3 = meta meta-xylene
1,4 = para para-xylene
However other names get more tricky, especially historical names, where
several names may be used for the same chemical and, even worse, different
chemicals can be described by the same name. Examples include:-
- calcium carbonate = limestone, chalk, calcite.
- calcium hydroxide = slaked lime, hydrated lime, caustic lime.
- calcium oxide = calx, lime, quicklime, unslaked lime, burnt lime.
- hydrochloric acid = muriatic acid, spirits of salts.
- nitric acid = aqua fortis.
- potassium carbonate = potash, artificial alkali, vegetable alkali.
- potassium hydroxide = caustic potash, lye.
- sodium carbonate - any form = soda, natural alkali, mineral alkali.
- anhydrous = soda ash.
- dodecahydrate = sal soda, washing soda.
- monohydrate = soda crystals.
- sodium chloride = rock salt.
- sodium hydroxide = caustic soda, lye, soda lye.
- sulfuric acid = oil of vitriol
Some old chemical terms are seldom encountered these days, but have very
specific meanings, eg
" flowers " described any product of sublimation, hence "flowers of sulfur".
" specific " in front of any quantity means " divided by mass ", hence
"specific gravity".
" ether " described a volatile liquid, not only compounds with the Cx-O--Cy
structure, and also often known today as "spirit".
" aromatic " described a liquid that had an aroma, not only those derived
from benzene, or which benzene ring structure.
" oil " described a liquid that was not miscible with water, thus it
described different products in different chemical industries :-
- Essential oils = volatile and odoriferous liquid plant extracts.
Essential oils can be obtained by extraction or distillation ( steam ),
often contain terpenes ( based on the isoprene structure ), are usually
smelly ( aromatic ), and are used for perfumes, flavours and aromas, eg
lemon oil and pine oil.
- Triglyceride oils = fats and oils based on the glycerol molecule that
can be obtained from plant and animal material, frequently by melting or
cold pressing. They are a significant, and important, component in our
diet, eg soya oil, lard, fish oils, and anhydrous milk fat.
- Petroleum oil = a mixture of a large number of hydrocarbons that are
usually derived from 0.1 to 3 billion-year-old organic matter. Crude oil
can contain hundreds of hydrocarbons with one to sixty carbon atoms, and
the hydrocarbons are usually grouped and reported by type, eg alkane
( paraffin ), alkene ( olefin ), or arene ( aromatic ).
Almost all old industries had easy-to-remember names for chemicals they
commonly encountered, but today many of those names can cause confusion
if used outside the industry. Some common examples, just from the petroleum
industry alone are:-
- " ether " is a volatile hydrocarbon fraction that does not contain the
Cx-O-Cy structure, eg petroleum ether ( aka petroleum spirit ).
- " naphthene " is a cyclic paraffin, does not contain naphthalene, and is
not a major component of naphtha ( refer Section 27.5 ).
- Benzene, toluene and xylene are often called benzol, toluol, and xylol,
even though they do not contain an -OH group.
- Benzine ( ligroin ) was a saturated hydrocarbon fraction that boiled
between 20C and 135C. Gasoline/petrol fractions are still called benzine
by some older people.
- Diesel fuel is often called "gas oil", which is a historical term for
hydrocarbon distillate fractions. Atmospheric gas oil has a boiling
range between 220C - 450C, and vacuum gas oil boils from 350C to 550C.
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