Iso groups

DMBCOl), dimethylbicyclo[3.2.1]octanes (DMBC02), ethylsubstituted bicyclooctanes (EBCO) and trimethylbicycloheptanes (TMBCH). The last group consists of trimethylbicyclo[2.2.1]heptanes, trimethylbicyclo[3.1.1]heptanes and dimethylbicyclo[2.2.2]octanes. Some representative structures of the Iso groups are shown in Figure 2. Major cracking products (CP) were identified as cyclic hydrocarbons C5-C9 and isobutane. The main heavy products (HP) were methyl-and dimethyldecalins, or their isomers. No olefins and only traces of aromatics were found in the products. Detailed information about the product analysis is reported elsewhere (22). 

Another example is found in Schedule 2.B.4, which contains an even larger number of chemicals defined in the following way Chemicals, except for those listed in Schedule 1, containing a phosphorus atom to which is bonded one methyl, ethyl or propyl (normal or iso) group but not further carbon atoms [exemption Fonofos, CAS 944-22-9] . 

Notice that an iso group has a methyl group on the next-to-the-last carbon in the chain. Notice also that all isoalkyl compounds have the substituent (OH, Cl, NH2, etc.) on a primary carbon, except for isopropyl, which has the substituent on a secondary carbon. The isopropyl group could have been called a yec-propyl group. Either name would have been appropriate because the group has an iso structural unit and a hydrogen has been removed from a secondary carbon. Chemists decided to call it isopropyl, however, which means that sec is used only for yec-butyl. 

Dividing the amino acids into classes makes them easier to learn. The aliphatic side chain amino acids include glycine, the amino acid in which R = H, and four amino acids with alkyl side chains. Alanine is the amino acid with a methyl side chain, and valine has an isopropyl side chain. Can you guess which amino acid—leucine or isoleucine— has an isobutyl side chain If you gave the obvious answer, you guessed incorrectly. Isoleucine does not have an iso group it is leucine that has an isobutyl substituent— isoleucine has a ec-butyl substituent. Each of the amino acids has both a three-letter abbreviation (the first three letters of the name in most cases) and a single-letter abbreviation. 

Fig. 5.12 The repeat unit of the polycarbonate molecule, identifying the main sources of intra-molecular P-relaxations the phenylene rings, around the isopropylidene (ISO) group and the carbonate (CAR) group, and showing the various torsion angles (p -(p6 considered in the relaxation simulation (from Hutnik et al. (1991a) courtesy of the ACS).

Iso-compounds have higher values than their normal isomerides, and if there are two iso-groups the value is still higher. Examples —Isopentane and normal pentane di-isobutyl and M-octane methyl isobutyrate and methyl butyrate. 

Alkanolamines with at least one NCH2CHOHCH,i grouping. Important materials include monoisopropanolamine NHX H CHOHCH, b.p. 159 C di-iso-propanolamine NH(CH CHOHCH b.p. 248 C triisopropanolamine NtCH -CHOHCHi). , b.p. 300 C. Manufactured from ammonia and propylene oxide. U ed, is weedkillers, as stabilizers for plastics, in detergents, alkanolaniine soaps for sweetening natural gas and in synthesis. 

The ISO 8681 standard, which treats all the petroleum products, groups lubricants, industrial oils and related products in the L Class. The international standard ISO 6743/0, accepted as the French standard NF T 60-162, subdivides the L Class into 18 families or categories. 

Hydrocarbon groups (FIA method) NF M 07-024 ISO/DIS 3837 ASTM D 1319 Chromatography on silica gel with fluorescent indicators... 

Black oils are a common category of reservoir fluids, and are similar to volatile oils in behaviour, except that they contain a lower fraction of volatile components and therefore require a much larger pressure drop below the bubble point before significant volumes of gas are released from solution. This is reflected by the position of the iso-vol lines in the phase diagram, where the lines of low liquid percentage are grouped around the dew point line. 

For some years now, standards for radioscopic applications have been in the drafting stage. This paper will discuss the present state of the preparations that the ad hoc working group "Radioscopy" of IIW, CEN and ISO is involved in. 

Sulphonic acids. The aromatic sulphonic acids and their alkali metal salts are soluble in water, but insoluble in ether (Solubility Group II). They are best characterised by conversion into crystalline S-benzyl-iso-thiuronium salts (see Section IV,33,2 and 111,85,5), which possess characteristic melting points. A more time-consuming procedure is to treat the well-dried acid or... 

Both maltose and cellobiose have a free anomeric hydroxyl group that is not involved in a glycoside bond The configuration at the free anomeric center is variable and may be either a or (3 Indeed two stereoisomeric forms of maltose have been iso lated one has its anomeric hydroxyl group m an equatorial orientation the other has an axial anomeric hydroxyl... 

Cholesterol was isolated m the eighteenth century but its structure is so complex that Its correct constitution was not determined until 1932 and its stereochemistry not verified until 1955 Steroids are characterized by the tetracyclic ring system shown m Figure 26 9a As shown m Figure 26 9b cholesterol contains this tetracyclic skeleton modified to include an alcohol function at C 3 a double bond at C 5 methyl groups at C 10 and C 13 and a C Hn side chain at C 17 Isoprene units may be discerned m var lous portions of the cholesterol molecule but the overall correspondence with the iso prene rule is far from perfect Indeed cholesterol has only 27 carbon atoms three too few for It to be classed as a tnterpene... 

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. 

Usually not favorable for separation of components that show similar Hquid-phase behavior, ie, steroisomers, homologous series, iso-notmA—neo isomers components to be separated must have some different functional group for MSA to affect Hquid-phase behavior differently. 

Chemical Composition. Wool wax is a complex mixture of esters of water-soluble alcohols (168) and higher fatty acids (169) with a small proportion (ca 0.5%) of hydrocarbons (170). A substantial effort has been made to identify the various components, but results are compHcated by the fact that different workers use wool waxes from different sources and employ different analytical techniques. Nevertheless, significant progress has been made, and it is possible to give approximate percentages of the various components. The wool-wax acids (Table 9) are predominantiy alkanoic, a-hydroxy, and CO-hydroxy acids. Each group contains normal, iso, and anteiso series of various chain length, and nearly all the acids are saturated. 

In the iso series, a branching methyl group is attached at the penultimate position, and in the anteiso series, at the antepenultimate position. 

Many substituted, ie, branched, fatty acids, particularly methacryUc, 2-ethylhexanoic, and ricinoleic acids, are commercially significant. Several substituted fatty acids exist naturally (Table 5). Fatty acids with a methyl group in the penultimate position are called iso acids, and those with a methyl group in the antepenultimate position are called anteiso acids (1) (see Carboxylic acids, branched-CHAIN acids). However, the term iso is often used in a broader sense to mean branched or mixtures of branched-chain industrial acids. 

Heats of Vapon a/ion andFusion. A simple linear summation of most of the Lyderson groups (187) has been proposed for heat of vaporization at the normal boiling point and heat of fusion at atmospheric pressure for a wide variety of organic compounds (188). Average errors of 1.2 and 4.3% for group contribution-based estimations of heats of vaporization for selected n- and iso-alkanes, respectively, have been reported (215). 

The iso)tazole ring is rather resistant to sulfonation. However, on prolonged heating with chlorosulfonic acid, 5-methyl-, 3-methyl- and 3,5-diraethyl-isoxazoles are converted into a mixture of the sulfonic acid and the corresponding sulfonyl chloride. The sulfonic acid group enters the 4-position even when other positions are available for substitution. The sulfonation of the parent isoxazole occurs only under more drastic conditions (20% oleum) than that of alkyl isoxazoles isoxazole-4-sulfonic acid is obtained in 17% yield. In the case of 5-phenylisoxazole (64), only the phenyl nucleus is sulfonated to yield a mixture of m-and p-arenesulfonic acid chlorides (65) and (66) in a 2 1 ratio (63AHC(2)365). 

The reactions of 3-unsubstituted iso.xazolium salts (123) with hydroxide, alkoxide, cyanide and azide ions have also been studied, and they can in general be rationalized in terms of the ketoketenimine intermediate (124). The results of these reactions are summarized below. The application of such reactions to 3-unsubstituted isoxazolium salts bearing substituents other than alkyl and aryl groups has received little attention, but 5-aminoisoxazolium salts have been studied (74CB13). 

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