Carbon chains, abbreviations

The Prelog-Djerassi lactone (abbreviated here as P-D lactone) was originally isolated as a degradation product during structural investigations of antibiotics. Its open-chain equivalent 3 is typical of the methyl-branched carbon chains that occur frequently in macrolide and polyether antibiotics. The compound serves as a test case for the development of methods of control of stereochemistry in such polymethylated structures. There have been more than 20 different syntheses of P-D lactone.24 We focus here on some of those that provide enantiomerically pure product, as they illustrate several of the methods for enantioselective synthesis.25... 

The Prelog-Djerassi lactone (abbreviated as P-D-lactone) was originally isolated as a degradation product during structural investigation of antibiotics. Its open-chain precursor 1, is typical of methyl-branched carbon chains that occur frequently in macrolide and polyether antibiotics. 

Before discussing the possibility of gas-phase cyanopolyyne chemistry, it seems necessary to summarize the present status of carbon chain molamle detections in interstellar space. Table 7 presents an overview of where these molecules are found and their respective abundances. These tables are an abbreviated update from Table 1 taken from Winnewisser and Walmsley (1979). It is seen that these molecules are found essentially in every type of molecular cloud from the cold dark cloud to the warm circumstellar environment, underlining the trend which has been observed over the past few years namely that complex organic molecules are not limited to a few sources only (in particular to the galactic center sources) but that they are spread over sources with rather different physical conditions. A qualifying statement may be in order here. 

CHj - CHj - CHj - 0 ) - The hydrophobic moiely can be a linear hydrocarbon chain (abbreviated where n Is the number of carbons) there can be a phenyl group (( i) in the chain (which may assist in the binding when the adsorbent is hydrophobic, and which makes analytical detection straightforward using ultraviolet absorption), some polypropylene segments, etc. Generally the composition can be abbreviated as Cj ())Ejj, etc. This code has been proposed by... 

They have a different structure, although they both have the same molecular formula. One is called normal butane, abbreviated to -butane the other may be called isobutane or 2-methylpropane - the latter name describes the structure of the compound, as you will see later. These compounds are isomers of one another. They are not the same compounds and have different melting points, boiling points and solubilities. Isomers are compounds which have the same moiecuiar formuia, but different moiecuiar structures. After butane, the longer the carbon chain of an alkane, the more structurai isomers are possible for a particular molecular formula. For example, there are 75 decanes (C10H22) and over three-hundred-thousand eicosanes (C20H42) ... 

The standard composition of an electrolyte in LlBs is a mixture of cycUc carbonates (such as ethylene carbonate (EC) and propylene carbonate (PC)) and chain carbonates (such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC abbreviated as MEC below), and diethyl carbonate (DEC)), to which about 1 mol/L of a lithium salt (such as lithium hexafluorophosphate (LiPF )) is added. Ube Industries, Ltd. discovered that if small amounts of impurities exist in the electrolyte, decomposition current generated from the impurities begins to flow, which leads to the formation of undesirable thick SET This spurred the development of a pioneering high-grade purification process for the base electrolyte in 1997 [16]. High purity is a key feature of functional electrolytes developed by Ube Industries, Ltd. and enables production of transparent and chemically stable electrolytes, in contrast to the conventional electrolytes which were less stable and brown owing to its low purity (Fig. 3.1). 

The butane with the unbranched carbon chain is called normal butane (abbreviated M-butane) it boils at 0.5°C and melts at -138.3 C. The branched-chain butane is called 2-methylpropane it boils at -11.7 C and melts at —159.5°C. These differences in physical properties are sufficient to establish that the two compounds, though they have the same molecular formula, are different substances. The structural arrangements of the atoms in methane, ethane, propane, butane, and 2-methylpropane are shown in Figure 19.4. 

A shorthand nomenclature is in common usage for fatty acids. They are written as two numbers separated by a colon. The number before the colon indicates the carbon chain length, and the figure after corresponds to the number of double bonds. Additional figures in parentheses show the position of double bonds, and the letters c, t, a, and e, show whether the bond is c/5-olefinic, rra 5-olefinic, acetylenic, or ethylenic. The position of the double bonds is numbered fi om the carboxyl group, but where it is more meaningful to number from the methyl end it is prefixed by o>. These abbreviations... 

The signals of the benzylic protons (5 3.6), the gem-dimethyl group (1.66, 1.83) and the vinylic proton (8 5.35) as, for example, in heptaphyl-line (9) are diagnostic for the 3 3 dimethyl allyl side chain (abbreviated as DMA). The doublets for each of the olefinic protons (J = 10 Hz) at 56.25 and 5.4 respectively together with the signal for the gem-dimethyl group on the carbon linked to the oxygen are indicative for the... 

All of these results were already presented at the ACS Houston Meeting on March, 1980.11 12 Since that time, further efforts have been made to synthesize novel condensation polymers by phase transfer catalyzed polycondensation. The present article deals with our recent works on the syntheses of carbon-carbon chain polymers and new types of polysulfides.1 The following abbreviations of phase transfer catalysts have been used throughout this article tetra-methylammonium chloride (TMAC), tetraethylammonium chloride (TEAC), tetrabutylammonium chloride (TBAC), benzyltriethylammonium chloride (BTEAC), cetyltrimethylammonium chloride (CTMAC), cetyltrimethyl-ammonium bromide (CTMAB), benzyltriphenylphosphonium chloride (BTPPC), cetyltributylphosphonium bromide (CTBPB), 15-crown-5 (15-C-5), 18-crown-6 (18-C-6), dibenzo-18-crown-6 (DB-18-C-6), dicyclohexyl-18-crown-6 (DC-18-C-6), dibenzo-24-crown-8 (DB-24-C-8), and dicyclohexyl-24-crown-8 (DC-24-C-8) ... 

A common abbreviation of hydrocarbon compounds is to designate the number of carbon atoms in the compound. A prefix is used to indicate the carbon chain form, while a subscripted suffix denotes the number of carbon atoms. 

Chart I. Trivial names (with recommended three-letter abbreviations in parentheses) and structures (in the aldehydic, acyclic form) of the aldoses with three to six carbon atoms. Only the D-forms are shown the L-forms are the mirror images. The chains of chiral atoms delineated in bold face correspond to the configurational prefixes given in italics below the names... 

Reversed-phase PLC precoated plates are based on silica gel matrices with chemical modifications in such a manner that the accessible polar, hydrophilic silanol groups at the silica gel surface are replaced by nonpolar, hydrophobic alkyl chains via silicon-carbon bonds. For preparative purposes, up to now only PLC precoated RP plates with C-18 modification are available. This abbreviation is often also designated as RP-18, meaning that an octadecyl alkyl chain is chemically bonded to the silica gel surface. 

FIGURE 9.1 GC/MS of total methyl esters of fatty acids standards and single fractions after PLC. Abbreviations first number (18 or 20) = number of carbon atoms in the chain second number (0 to 5) = number of double bounds n = normal chain i =isoacid ai = anteisoacid m-br =multi-branched acid. (From Rezanka, T., J. Chromatogr. A, 727, 147-152, 1996. With permission.)... 

Abbreviations for pheromone molecules follows the following format example (Z)-7-do-decen-l-yl acetate is shortened to Z7-12 OAc where Z denotes the double bond configuration, 7 the double bond position, 12 the number of carbons in the chain OAc indicates the functional group as an acetate ester. 

When electron microscope studies first showed clearly the anisotropy of carbon black particles the appearance was of a chain of particles fused together, to which the term reticulate chain structure was given, later abbreviated simply to structure . The degree of structure has an influence on the level of reinforcement conferred by the carbon black. 

The formation of a network or net-like structure. In rubber technology this term was first applied to the anisotropy of carbon black particles, which were described as having a reticulate chain structure , later abbreviated simply to structure . Retracted Spew... 

Carbon actually has the capacity to link with only a relatively few other chemicals, such as oxygen, abbreviated O nitrogen, abbreviated N chlorine, abbreviated Cl and sulfur, abbreviated S but it can do so in an extraordinary complexity of chains, loops, and cyclic variants of loops. 

Four types of organic amines exist, as shown in Table 4.8 primary amines RNHj, secondary R2NH2, tertiary RsNH, and quaternary R4N (Appendix D). The hydrocarbon chain R is usually of length Cg-Cu, commonly a straight aliphatic chain, but branched chains and aromatic parts also occur. In general the amines extract metal complexes in the order tertiary > secondary > primary. Only long-chain tertiary and—to a smaller extent—quarternary amines are used in industrial extraction, because of their suitable physical properties trioctylam-ine (TOA, 8 carbons per chain) and trilauryl amine (TLA, 12 carbons per chain) are the most frequently used. For simplicity we abbreviate all amines by RN, and their salts by RNH L . 

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