Position, on carbon chain

P Position on carbon chain attached to metal (J denotes one carbon beyond the a position... 

Number the carbons of the parent chain beginning at the end nearer the first substituent, whether alkyl or halo. Assign each substituent a number according to its position on the chain. 

Thus, the hydrogen has moved from the 1 position to the 5 position on the chain. The 1 in the designation [1,5] indicates that at one end of the new cr bond is an atom (the hydrogen) that also was at one end of the old cr bond. The 5 indicates that the other end of the new cr bond is formed at the 5 position along the carbon chain, atom number 5. 

To illustrate how these names were obtained, consider structure (c). The longest continuous chain that contains the double bond is made up of 4 carbons. Therefore, the parent chain is butene, the "ene" indicative of the presence of a double bond. The double bond is situated on carbon so that it is 1-butene. The two substituents, both methyl groups (CH3), are positioned on carbon 3 because the numbering system is from the end of the parent chain nearest the double bond. Hence, for (c) the nomenclature is 3,3-Dimethyl-l-butene. 

To translate a name to a structure, identify the carbon chain from the root name and add the substituents to the correct position on the chain. 

Similarly, the two chemically identical groups X, positioned on carbon atoms of opposite (/ ,5)-configuration in a weso-substrate, can react at different rates in a hydrolase-catalyzed reaction (Scheme 2.4). So, the optically inactive meso-substrate is transformed into an optically active product due to the transformation of one of the reactive groups from X into Y along with the destruction of the plane of symmetry within the substrate. Numerous open-chain or cyclic c/s-weso-diesters have been transformed into chiral monoesters by this technique [30]. Again, for dicarboxylates the reaction usually stops after the first step at the carboxylate monoester stage, whereas two hydrolytic steps are usually observed with diacetoxy esters [31]. The theoretical yield of chiral product from single-step reactions based on an enantioface or enantiotopos differentiation or a desymmetrization of meso-compounds is always 100%. 

The chemistry of aromatic alkylation is more complicated than implied by equations (15, 16, 17). Polymerization, CP production, and the isomerization of heavier olefins also occur. Olson (32) has reported many details of the positional isomerization of 1-aIkenes in the Ce—Cm range. Using 1-dodecene as an example, the alkylated product is a mixture of 2- through 6-dodecyl benzenes. In the absence of isomerization, only 2-dodecyl benzene is produced. Attachment at the first carbon atom is not expected when propylene or heavier olefins are employed since primary cations would then be obtained. Secondary cations are however more stable (or preferred) and lead to the attachment at the second or higher carbon atom of the cation. Olson suggests that positional isomerization involves the formation of dodecyl acid sulfates or dodecyl fluorides when sulfuric acid or HF are used as catalysts reverse reactions then lead to the formation of olefins with double bonds in a new position on the chain. In one example reported, at least 80% of the dodecene isomerized before alkylation (by reactions similar to eqs. 16 and 17). Olson also found that some of the initial dodecylbenzene produced were isomerized. The 2-dodecyl benzene that was initially produced isomerized in the presence of AICI3 catalysts to give from 3-dodecyl to 6-dodecyl benzenes. 

Tethers based on carbon chains are neutral and have electronically almost no influence. A forced alignment of the electron-rich aryl moieties in 15 does not result upon anodic treatment in the desired ortho,ortho-co yp eA product. Short tethers in 15 promote intermolecular coupling reactions, whereas longer spacers allow the formation of ortho,par a products [27]. The electronic activation in position para is dominant and a simple aUcyhdene tether is not exploitable for synthesis (Scheme 6). 

The CH vector autocorrelation function can be readily measured in a simulation and resolved for specific positions on the chain. The angle brackets in Eq. (13) indicate an averaging procedure over chemically identical carbons in the system and over multiple time origins along the generated trajectory of the model system. To calculate its Fourier transform, this relaxation function is then best fit either with some model predictions, for instance based on local conformational dynamics plus Rouse mode contributions [11], or with some phenomenological fit function. In our experience, 2(0 is generally very well reproduced by a superposition of an... 

Alkanes are named by determining the number of carbons in their parent hydrocarbon. Substituents are listed as prefixes in alphabetical order, with a number to designate their position on the chain. 

The enantiomeric purity of carboxylic acids with remotely disposed chiral centers can be analyzed using 2-(anthracene-2,3-dicarboximido)cyclohexanol 36. Similar to the derivative with a carboxylic acid moiety on the cyclohexane ring 10 described earlier for the analysis of alcohols, the ester derivative of carboxylic acids with 36 positions the carbon chain of the substrate over the anthryl ring. Carboxylic acids with the stereocenter at C12 still show enantiomeric discrimination in the derivative with 36. ... 

Substitution Reactions on Side Chains. Because the benzyl carbon is the most reactive site on the propanoid side chain, many substitution reactions occur at this position. Typically, substitution reactions occur by attack of a nucleophilic reagent on a benzyl carbon present in the form of a carbonium ion or a methine group in a quinonemethide stmeture. In a reversal of the ether cleavage reactions described, benzyl alcohols and ethers may be transformed to alkyl or aryl ethers by acid-catalyzed etherifications or transetherifications with alcohol or phenol. The conversion of a benzyl alcohol or ether to a sulfonic acid group is among the most important side chain modification reactions because it is essential to the solubilization of lignin in the sulfite pulping process (17). 

DiisononylPhthalate andDiisodeeylPhthalate. These primary plasticizers are produced by esterification of 0x0 alcohols of carbon chain length nine and ten. The 0x0 alcohols are produced through the carbonylation of alkenes (olefins). The carbonylation process (eq. 3) adds a carbon unit to an alkene chain by reaction with carbon monoxide and hydrogen with heat, pressure, and catalyst. In this way a Cg alkene is carbonylated to yield a alcohol a alkene is carbonylated to produce a C q alcohol. Due to the distribution of the C=C double bond ia the alkene and the varyiag effectiveness of certain catalysts, the position of the added carbon atom can vary and an isomer distribution is generally created ia such a reaction the nature of this distribution depends on the reaction conditions. Consequendy these alcohols are termed iso-alcohols and the subsequent phthalates iso-phthalates, an unfortunate designation ia view of possible confusion with esters of isophthaUc acid. 

Disulfides. The introduction of disulfide bonds can have various effects on protein stability. In T4 lyso2yme, for example, the incorporation of some disulfides increases thermal stability others reduce stability (47—49). Stabili2ation is thought to result from reduction of the conformational entropy of the unfolded state, whereas in most cases the cause of destabili2ation is the introduction of dihedral angle stress. In natural proteins, placement of a disulfide bond at most positions within the polypeptide chain would result in unacceptable constraint of the a-carbon chain. 

The efficiency of reduction of benzophenone derivatives is greatly diminished when an ortho alkyl substituent is present because a new photoreaction, intramolecular hydrogen-atom abstraction, then becomes the dominant process. The abstraction takes place from the benzylic position on the adjacent alkyl chain, giving an unstable enol that can revert to the original benzophenone without photoreduction. This process is known as photoenolization Photoenolization can be detected, even though no net transformation of the reactant occurs, by photolysis in deuterated hydroxylic solvents. The proton of the enolic hydroxyl is rapidly exchanged with solvent, so deuterium is introduced at the benzylic position. Deuterium is also introduced if the enol is protonated at the benzylic carbon by solvent ... 

Step 3 Write the full name. Number the substituents according to their positions in the chain, and list them alphabetically. Indicate the position of the double bond by giving the number of the first alkene carbon and placing that number directly before the parent name. If more than one double bond is present, indicate the position of each and use one of the suffixes -diene, -triene, and so on. 

The influence of the a-bond isomerism is in agreement with the slow exchange spectra of 2,3-dimethylbutane and 1,2-dimethycylohexane in solution 16,17). Taking into account the different isomeric states of the bonds in a- and P-position on both sides of the observed carbons the slow exchange spectra of CH2-chain molecules have to be explained by conformational variations in chain segments of five carbon atoms. 

A positive value of ME means that the insertion of a hetero atom or group makes the molecule more lipophilic. If ME is negative, the hetero surfactant is more hydrophilic. In general, hetero atom insertion hydrophilizes the surfactant molecule as does the shift of the hetero group to the middle of the carbon chain [71]. ME values are temperature-dependent. / and ME values can also be useful to take into account the influence of various cations on the critical micelle concentration. 

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