Iso- prefix

Isophthaloyl chlorides, 19 715 Isophytol, 24 502, 550 Isopolytungstate compounds structures of, 25 383-384 Iso prefix, 13 594-595 Isoprene, 24 501 Alfrey-Price parameters, 7 617t block copolymer synthesis, 7 647t butyl rubber polymers, 4 433 commercial block copolymers, 7 648t glass transition and melting... 

In branched alkanes, if there is one methyl (—CH3) group on the second carbon, the "iso" prefix is added to the front of the parent name. 

Fig. 5.1. Examples of aliphatic and aromatic compounds. A. An isoprene group, which is an aliphatic group. The iso prefix denotes branching, and the ene denotes a double bond. B. A benzene ring (or phenyl group), which is an aromatic group.

Iso- Prefix denoting that a compound is an isomer, e.g. isopentane (CH3CH(CH3)C2H5,... 

The iso prefix indicates a methyl group on the penultimate carbon of the chain, starting from the carboxylic acid function 15 I... 

The suffix /Tier in the word isomer is derived from the Greek word meros meaning part share or por tion The prefix /so is also from Greek (isos meaning the same ) Thus isomers are different molecules that have the same parts (ele mental composition)... 

Note the usage of the prefixes iso-, neo-, sec-, and tert-, and note when italics are employed. Italicized prefixes are never involved in alphabetization, except among themselves thus 5-ec-butyl would precede isobutyl, isohexyl would precede isopropyl, and 5-ec-butyl would precede rert-butyl. 

In the petroleum industry the International Union of Pure and Applied Chemistry (lUPAC) system is in widespread use for naming organic compounds. Two points, however, regarding group names and the prefix, iso, call for comment. 

The prefix iso is used loosely to denote branched alkanes or alkenes that have one or more methyl groups only as side chains. 

Botanical names are printed in italics. Prefixes snch as nor-, iso-, proto-, apo-, are printed in italics and disregarded for indexing purposes.- Where more than one page number is given, a chief descriptive reference is indicated hy the use of heavier type.)... 

On other occasions, the wrong material has beer delivered because prefixes such as n- or iso- were left off when ordering. 

Branched-chain alkanes, also known as isoparaffins or isoalkanes, are possible when n > 4. The prefix iso is used when two methyl groups are attached to a terminal carbon atom of an otherwise straight chain and the prefix neo when three methyl groups are attached in that manner. Branched-chain alkanes are sometimes regarded as normal alkanes with attached substituent alkyl groups. An example is... 

When writing an alkane name, the nonhyphenated prefix iso- is considered part of the alkyl-group name for alphabetizing purposes, but the hyphenated and italicized prefixes sec- and tert- are not. Thus, isopropyl and isobutyl are listed alphabetically under i, but sec-butyl and ferf-butyl are listed under b. 

The chain and branched chain saturated hydrocarbons make up a family called the alkanes. Some saturated hydrocarbons with five carbon atoms are shown in Figure 18-11. The first example, containing no branches, is called normal-pentane or, briefly, n-pentane. The second example has a single branch at the end of the chain. Such a structural type is commonly identified by the prefix iso- . Hence this isomer is called /50-pentane. The third example in Figure 18-11 also contains five carbon atoms but it contains the distinctive feature of a cyclic carbon structure. Such a compound is identified by the prefix cyclo in its name—in the case shown, cyclopentane. 

Nonsystematic names for organic compounds may still be found in the chemical literature and chemical supply catalogs, and so it is important to be somewhat familiar with these as well as with the IUPAC rules. Give the systematic name for (a) isobutane and (b) isopentane, (c) Formulate a rule for the usage of the prefix iso- and predict the structure of isohexane. Structures for these compounds can be found on the Web site for this book. 

It should be noted that italicised hyphenated prefixes which indicate structure, such as cis-. o-, m-, tert-, mixo-, N-. 0-, etc., have been ignored during the alpha-sorting routine used on this index and the group-lists, while the roman character structural prefixes iso and neo, and roman multiplying prefixes such as di, tris, tetra and hexakis, have been included in the indexing procedure. 

Sometimes the prefix iso is used to signify the less stable isomer as in isocrotonic acid which is cis and it is less stable. Similarly the prefix alio is also used to signify the less stable isomer e.g., allocinnamic acid. 

If a stable enzyme form isomerizes and these isomerization steps are a part of the reaction pathway, the term Iso is provided. For a Uni Uni mechanism in which an isomerization step occurs [e.g., the reaction sequence E -I- A EA EA FP FP F -I- P and F E] is designated an Iso Uni Uni scheme. If more than one isomerization event occurs, then the prefixes di-, tri-, etc, are utilized with Iso. Note that this aspect of the nomenclature does not refer to isomerization steps which may or may not occur between central complexes. 

The term tactic is taken from the Greek word taktikos, meaning "placed in order. The prefixes iso, syndio, and a mean same, two together, and "without, respectively. 

Polymer tacticity These terms are first recorded in J. Polymer Sci. 20,251,1956. The words originate from Greek words that prefix tatto (put in order) a) iso- (the same), syndo- (every two and a- (not at all). 

Ischaemia A deficiency of blood supply to a part of the body relative to its localized requirements. Iso The prefix (meaning the same) given to a compound having the same number and kind of atoms as another compound, as in /.vomer. 

The chemicals are listed in straight alphabetical order, letter by letter. Compounds consisting of two or more words are compiled as if they were a single word. Prefixes and numerals are disregarded in the alphabetizing. In cases were prefixes are an integral part of the chemical s name they are placed in normal alphabetical order (bis-, cyclo-, di-, iso-, neo-, tetra-, tri-). 

The continuous chain hydrocarbons are known as normal hydrocarbons, and the prefix n- is usually attached to the name. The branched-chain hydrocarbons may have the prefix iso- attached to the name. Usually the prefix iso- is reserved for substances with two methyl groups attached to carbon atoms at the end of an otherwise straight chain. In a straight chain, each carbon atom is connected to no more than two other carbon atoms. The prefix neo- denotes three methyl groups on a carbon atom at the end of a chain. For example, the isomers of pentane are illustrated below. 

The ISO and BS standards now express the ozone concentration in ppb to satisfy prefix purists, with the more traditional and familiar pphm in brackets. However, ASTM D1149 now uses partial pressure in mPa to eliminate differences due to atmospheric pressure at different altitudes, but ISO 1431-1 only mentions it in a note. ISO 1431-3 gives the options of mg/m3 and mPa in addition to pphm but ppb had not yet become fashionable in 2000 when it was published. The significance of partial pressure has been demonstrated by Veith and Evans48. Basically, the rate of cracking is a function of the collision rate of ozone molecules with the rubber. At different atmospheric pressures in the cabinet, the collision rate, and hence the cracking, will be different at the same concentration expressed in pphm. Clearly, the effect is important in locations with, relatively speaking, extremes of pressure from standard. 

In addition to the basic classification as primary, secondary, or tertiary, alcohols may be further grouped according to other structural features. Aromatic alcohols contain an aryl group attached to the carbon having the hydroxyl function aliphatic alcohols contain only aliphatic groups. The prefix iso usually indicates branching of the carbon chain. 

The prefix iso is from the Greek word meaning the same or alike. 

The situation with regard to naming alkyl substituents has been muddied considerably by the fact that the IUPAC rules allow use of trivial names for a few alkyl groups. Thus sec-butyl sometimes is used in place of 1-methylpropyl, and rcr/-butyl in place of 1,1-dimethylethyl. These and other examples are included in parentheses in Table 3-2. Further odd-ball but less official customs are the prefix iso, which is reserved for substituents with two methyl groups at the end of an otherwise straight chain (e.g., isopropyl), and the prefix neo,... 

Isomers are unique molecules with the same molecular formula. "Iso" is a Creek prefix meaning "the same" or "equal". A lone molecule cannot be an isomer by itself. It must be an isomer to another molecule. Two molecules are isomers if they have tire same molecular formula but are different compounds. 

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