Bonds positions

Acylation of the vinylogous pyrrolidine amide of dimedone with acetic anhydride or acetyl chloride led (possibly indirectly) to the carbon acylation product, whereas trichloroacetyl chloride gave rise to products derived from attack of chloride at the oxygenated double bond position in an initial 0-acylation product (401-404). 

In order to avoid as far as possible double bond positional isomers, a problem quite common in drugs with indene moieties, N-trityl-2-hydroxymethylmorpholine (23) was reacted with the potassium. salt of 4-hydroxy-1-indanone (24) in DMSO solvent to give condensation product 25 in good yield. Reduction of 25 with LLAIH produced the hydroxyindane which was dehydrated and deprotected with HCl to give indeloxazine (26) [8]. 

Pyrrolidine derivative of monounsaturated methyl or ethyl ester for determining the double bond position. 

For maximum selectivity, low temperatures are essential under such conditions, simple alcohols, even allylic, are unaffected, and with unsaturated lactones as substrates, the double-bond position stays unchanged. 

It was pointed out in my 1949 paper (5) that resonance of electron-pair bonds among the bond positions gives energy bands similar to those obtained in the usual band theory by formation of Bloch functions of the atomic orbitals. There is no incompatibility between the two descriptions, which may be described as complementary. It is accordingly to be expected that the 0.72 metallic orbital per atom would make itself clearly visible in the band-theory calculations for the metals from Co to Ge, Rh to Sn, and Pt to Pb for example, the decrease in the number of bonding electrons from 4 for gray tin to 2.56 for white tin should result from these calculations. So far as I know, however, no such interpretation of the band-theory calculations has been reported. 

The resonating-valence-bond theory of the electronic structure of metals is based upon the idea that pairs of electrons, occupying bond positions between adjacent pairs of atoms, are able to carry out unsynchronized or partially unsynchronized resonance through the crystal.4 In the course of the development of the theory a wave function was formulated describing the crystal in terms of two-electron functions in the various bond positions, with use of Bloch factors corresponding to different values of the electron-pair momentum.5 The part of the wave function corresponding to the electron pair was given as... 

Either double bond position (43) or (44) is satisfactory but only (44) leads to an easy disconnection,... 

Metal clusters on supports are typically synthesized from organometallic precursors and often from metal carbonyls, as follows (1) The precursor metal cluster may be deposited onto a support surface from solution or (2) a mononuclear metal complex may react with the support to form an adsorbed metal complex that is treated to convert it into an adsorbed metal carbonyl cluster or (3) a mononuclear metal complex precursor may react with the support in a single reaction to form a metal carbonyl cluster bonded to the support. In a subsequent synthesis step, metal carbonyl clusters on a support may be treated to remove the carbonyl ligands, because these occupy bonding positions that limit the catalytic activity. 

On the other hand, in order to preserve the cold properties of the fuel (Cloud Point, Pour Point and low-temperature filterability), it is mandatory not to increase the melting point, that in turn depends on both the saturated compound (stearic acid, C18 0) content and the extent of cis/trans and positional isomerization as the difference in melting point between the cis and trans isomer is at least 15°C according to double bond position as shown in Table 1. 

Monounsaturated fatty acid influence of double bond position ... 

Polyene Cyclization. Perhaps the most synthetically useful of the carbo-cation alkylation reactions is the cyclization of polyenes having two or more double bonds positioned in such a way that successive bond-forming steps can occur. This process, called polyene cyclization, has proven to be an effective way of making polycyclic compounds containing six-membered and, in some cases, five-membered rings. The reaction proceeds through an electrophilic attack and requires that the double bonds that participate in the cyclization be properly positioned. For example, compound 1 is converted quantitatively to 2 on treatment with formic acid. The reaction is initiated by protonation and ionization of the allylic alcohol and is terminated by nucleophilic capture of the cyclized secondary carbocation. 

Rando and von E. Doering have investigated the synthetic utility of double bond positional isomerization in the photolysis of a,j8-unsaturated esters,<106)... 

Double bond position, counting from the functional group... 

Fig. 3A,B Double-bond positions of monoenyl components in Type I pheromones A counting from the functional group B counting from the terminal methyl group. See text for components with an odd numbered chain (C13, C15, and C17)...

When a sufficient amount of sample is available (ca. 1 pg), monoenyl compounds can be analyzed by micro-ozonolysis with and without a solvent [146, 165]. Ozonides, directly injected into GC-MS, are reductively decomposed into two aldehydes by heat. Besides this chemical reaction, the double-bond position is easily and high-sensitively confirmed by making an adduct with DMDS, which... 

Fig. 9A,B GC-MS analysis of the pheromone extract of Anadevidia peponis (Noctuidae, 1 FE) treated with DMDS A TIC B mass chromatograms [141]. The mass chromatograms, which are multiplied by indicated factors, monitor the M+ of DMDS adducts derived from C10 to C16 monoenyl acetates (m/z 292,320,348, and 376) and some diagnostic fragment ions (m/z 89,117,145,173,175,203,231, and 259) to determine their double-bond position. Peaks I-VI indicate the DMDS adducts of the following components in the pheromone gland Z5-10 OAc (I),Z5-12 OAc (II),Z7-12 OAc (III), ll-12 OAc (IV),Z9-14 OAc (V), and Zll-16 OAc (VI)...

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. 

Fig. 19 Our hybrid microrelaxation model. The solid circles are occupied by a polymer chain. The dashed lines show the new bond positions produced by a move consisting of kink generation and partial sliding diffusion along the chain. The arrows indicate the directions of monomer jumping [134]... 

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