Common name

Some organic compounds are identified using common names that do not follow the lUPAC system of nomenclature. Many of these names were given to molecules long ago, before the lUPAC system was adopted. These names are still widely used. For example, isopentane, an older name for one of the C5H12 isomers, is still allowed by lUPAC rules, although it can also be named 2-methylbutane. We will follow the lUPAC system except in cases in which a common name is widely accepted. 

In the past several years organic chemists have attempted to synthesize some unusual cycloalkanes not found in nature. Dodecahedrane, a beautifully symmetrical compound composed of 12 five-meinbered rings, is one such molecule. It was first prepared at Ohio State University in 1982. The lUPAC name for dodecahedrane is undecacyclo[9.9.9.0 .a - .(f V 0. 0 0 ° . 0 .0 ]eicosane, a name so complex that few trained organic chemists would be able to identify its structure. 

For a more comprehensive list of unusual polycyclic alkanes (including windowpane, davidane, catenane, propellane, and many others), see Organic Chemistry The Name Game by Alex Nickon and Ernest Silversmith, Pergamon Press, 1987. 

In addition to the rules for naming compounds, there are also some common names for some simple and common organic compounds. You should be aware of these names to the extent lhaL your course demands this of you. Each course will be 

IUPAC name inethannic acid Common name formic acid 

IUPAC name ethanoic acid Common name acetic acid 

IUPAC name methanal Common name formaldehyde 

IUPAC name ethanal Common name acetaldehyde 

Most of these examples are so common that it is quite rare to hear someone refer to these componnds by their lUPAC names. Their common names are much more common, which is why we call them common names. 

Ethers are typically called by their common names. The group on either side of the oxygen atom is named as a snbstitnent before the term ether. Examples  

The lUPAC method wonld be to treat the oxygen atom like a carbon atom and then indicate where the oxygen atom is with the term oxa-. So diethyl ether would be 3-oxapentane, but no one calls it that. Everyone calls it diethyl ether (or even just ethyl ether). It is not a bad idea to familiarize yourself with all of the common names listed in whatever textbook yon are nsing. 

Diethyl ether (also just ethyl ether) 

Assign the lower number to the 1 substituent alphabetically the b of butyl before the m of methyl. 

Problem 4.15 Give the structure corresponding to each lUPAC name. 

Problem 4.16 Give the lUPAC names for the five cyclic isomers of molecular formula C5H10 in Problem 4.9. 

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Langmuir also gave needed emphasis to the importance of employing pure substances rather than the various natural oils previously used. He thus found that the limiting area (at the Pockels point) was the same for palmitic, stearic, and cerotic acids, namely, 21 per molecule. (For convenience to the reader, the common names associated with the various hydrocarbon derivatives most frequently mentioned in this chapter are given in Table IV-1.)... 

Proger, Stern and Ilberg, System der organischen Verbindungen, 246 pp. (1926). This volume lists the 4877 system numbers and includes the common names with appropriate references to " system numbers (Julius Springer Edwards Brothers). 

Krypton-85 has been used for over 25 years to measure the density of paper as it is amanufactured. The total weight of paper can be controlled to a very accurate degree by the use of krypton 85 and other radioactive nuclides. The common name for such a device is a beta gague that can measure the thickness of a material. 

Strike breaks off a piece of the plant and smells it. Oh Yeah That s the bomb The plant is called Piper auritum. Its common name is Hojo Santa. Strike loves Strike s mother. 

The linking methine cheiin includes an even number of methine groups (0,2,4). They are commonly named as derivatives of the ketomethylene ring, for example. 3-ethyl-5-(3-ethyl-4,5-diphenylthiazolin-2-ylidene)-rhodanine (5) and 4-[4- 3-methyl-4,5-diphenylthiazolin-2-ylidene)-2-butenylidene]-3-methyl-l-p-sulfophenyl-2-pvrazolin-5-one (6) (Scheme 4). 

Branched alkyl groups are named by using the longest continuous chain that begins at the point of attachment as the base name Thus the systematic names of the two C3H7 alkyl groups are propyl and 1 methylethyl Both are better known by their common names n propyl and isopropyl respectively... 

Dimethylethyl group (common name tert butyl)... 

Two constitutionally isomeric alkanes have the molecular formula C4H10 One has an unbranched chain (CH3CH2CH2CH3) and is called n butane, the other has a branched chain [(CH3)3CH] and is called isobutane Both n butane and isobutane are common names... 

A single alkane may have several different names a name may be a common name or it may be a systematic name developed by a well defined set of rules The most widely used system is lUPAC nomencla ture Table 2 6 summarizes the rules for alkanes and cycloalkanes Table 2 7 gives the rules for naming alkyl groups... 

The names cited are common names which have been m widespread use for a long time and are acceptable m lUPAC nomenclature We will introduce the systematic nomen clature of these ring systems as needed m later chapters... 

Cubane (CgHg) is the common name of a polycyclic hydrocarbon that was first synthesized in the early 1960s As its name implies its structure is that of a cube How many rings are pres ent in cubane" ... 

Functional class names are part of the lUPAC system they are not common names... 

Dichloromethane trichloromethane and tetra chloromethane are widely known by their common names methylene chloride chloroform and carbon tetrachloride respectively... 

Handbooks are notorious for listing compounds according to their common names One gives the name sec isoamyl alcohol for a compound which could be called 1 2 dimethylpropyl alcohol according to the lUPAC functional class rules The best name for this compound is the substitutive lUPAC name What is it" ... 

Epichlorohydnn is the common name of an industrial chemical used as a component in epoxy cement The molecular formula of epichlorohydnn is C3H5CIO Epichlorohydnn has an epoxide functional group it does not have a methyl group Write a structural formula for epichloro hydrin... 

Isoamyl acetate is the common name of the substance most responsible for the characteris tic odor of bananas Wnte a structural formula for isoamyl acetate given the information that it IS an ester in which the carbonyl group bears a methyl substituent and there is a 3 methylbutyl group attached to one of the oxygens... 

Uschandm is the common name of a poisonous natural product having the structure shown Locate all of the following in uschandm... 

We give alkenes lUPAC names by replacing the ane ending of the corresponding alkane with ene The two simplest alkenes are ethene and propene Both are also well known by their common names ethylene and propylene... 

Ethylene is an acceptable synonym for ethene in the lUPAC system Propylene isobuty lene and other common names ending in ylene are not acceptable lUPAC names... 

We noted m Section 2 13 that the common names of certain frequently encoun tered alkyl groups such as isopropyl and tert butyl are acceptable m the lUPAC sys tern Three alkenyl groups—vinyl, allyl, and isopropenyl—are treated the same way... 

The common names of these alkenes are c/s and trans di tert butylethylene In cases such as this the common names are somewhat more convenient than the lUPAC names because they are more readily associated with molecular structure... 

CIS Pinane and trans pinane are common names that de note the relationship be tween the pair of methyl groups on the bridge and the third methyl group... 

Three membered rings that contain oxygen are called epoxides At one time epox ides were named as oxides of alkenes Ethylene oxide and propylene oxide for exam pie are the common names of two industrially important epoxides... 

The two dimers of 2 methylpropene shown in the equation can be converted to 2 2 4 trimethylpentane (known by its common name isooctane) for use as a gasoline additive Can you suggest a method for this conversion ... 

The group H2C=CHCH2 — IS known as allyT which IS both a common name and a permissible lUPAC name It is most often encountered m functionally substituted deriv atives and compounds containing this group are much better known by their functional class lUPAC names than by their substitutive ones... 

Allyl IS the common name of the parent group H2C=CHCH2— and is an acceptable name m lUPAC nomenclature... 

Many simple monosubstituted derivatives of benzene have common names of long stand mg that have been retained m the lUPAC system Table 111 lists some of the most important ones... 

These common names are acceptable in lUPAC nomenclature and are the names that will be used in this text... 

The common names of (di chloromethyl)benzene and (trichloromethyl)benzene are benzal chloride and benzo trichloride respectively... 

Ethylene glycol and propylene glycol are common names for these two diols and are acceptable lUPAC names Aside from these two compounds the lUPAC system does not use the word glycol for naming diols... 

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