Terminal carbons

At least two pathways have been proposed for the Nenitzescu reaction. The mechanism outlined below is generally accepted." Illustrated here is the indolization of the 1,4-benzoquinone (4) with ethyl 3-aminocrotonate (5). The mechanism consists of four stages (I) Michael addition of the carbon terminal of the enamine 5 to quinone 4 (II) Oxidation of the resulting hydroquinone 10 to the quinone 11 either by the starting quinone 4 or the quinonimmonium intermediate 13, which is generated at a later stage (HI) Cyclization of the quinone adduct 11, if in the cw-configuration, to the carbinolamine 12 or quinonimmonium intermediate 13 (IV) Reduction of the intermediates 12 or 13 to the 5-hydroxyindole 6 by the initial hydroquinone adduct 7 (or 8, 9,10). 

Kohle-gehalt, m. carbon content, -hydrat, n. carbohydrate, -klemme, /. Elec.) carbon terminal, -kom, n. carbon granule, -lampe, /. carbon lamp, -lichtbogen, m. Elec.) carbon arc. 

Kohlen-karbonit, n. kohlencarbonite (trade name of an explosive), -klein, n. small coal, -klemme,/, (Elec.) carbon terminal, -kom, n. carbon granule, -licht, n. carbon light, -losche, /, coal dust or slack, -mehl, n, coal dust, powdered coal, -meiler, m, charcoal pile, -monoxyd, n, carbon monoxide, -mulm, m, coal dust, slack charcoal dust, -olsaure, /. carbolic acid, -oxycblorid, n. carbon oxychloride, carbonyl chloride,... 

Figure 2 Models for the carbon-terminated 3C-SiC(001)c(2x2) surface (a) staggered C=C-dimer model, (b) C2 groups in Si bridge sites. Cf. text.

The rate of polymerization in the dark, i.e., when the initiation is stopped, was used to uncouple the kinetic constants for termination and propagation. By performing these after-effect experiments (13-15) at various stages in the reaction, the kinetic constants for bimolecular carbon-carbon termination and propagation were characterized as a function of conversion. 

Termination of active radicals can occur via three mechanisms carbon-carbon termination, cross termination and recombination of DTC radicals. These reactions appear as ... 

In the model, the kinetic constants for propagation and termination are allowed to vary as a function of free volume, as suggested by Marten and Hamielec (16) and Anseth and Bowman (17). To account for diffusional limitations and still predict the non-diffusion controlled kinetics, the functional forms for the propagation and carbon-carbon termination kinetic constants are ... 

Thus, the parameters characterizing propagation and carbon-carbon termination are experimentally determined, as are initiator molar absorptivities (from spectrophotometry). If kt so, ktCS0, AtSS, AtCS, fcSS and fcCS parameters for DTC-DTC and cross termination are intuitively chosen (based on comparisons with parameters for kp and kj the system can be quantitatively modelled. The parameters used for the simulations presented here can be found in Table I. 

Answer (c), butanoic acid is the most appropriate name for this molecule. It has a four carbon atom chain with an acid group on the 1st carbon (terminal carbon atom)... 

Very recently, Fujii and Ohno developed a route for the synthesis of dihydroquinoline and chromene derivatives under mild reaction conditions. Hydroarylation leads to a highly selective formation of six-membered rings, depending on the carbon (terminal or central allenic) that reacts with the aryl moiety [50]. 

Fig. 4 The energy distribution for photoelectrons ejected with a left (negative spin polarization -red, solid) or right circular (positive spin polarization - blue, dashed) polarized laser. The electrons are transmitted through films of l- and D-polyalanine both bound to the surface through the carbon terminal (a and c, respectively), and through a film of D-polyalanine bound to the surface through the N-terminal (b). Angew. Chem. Int. Ed. 2002, 41, 761 Fig. 2 Copy right permission granted.

Three steps are needed to complete the synthesis. Treatment of HC CH with NaH forms the acetylide anion, which undergoes an Sn2 reaction with an alkyl halide to form a four-carbon terminal alkyne. Hydration of the alkyne with HgO, H2SO4, and HgS04 yields the target compound. 

As terminators, all the atoms of interest (i.e. C, H, N, P, O, S, halogens) can be considered terminators of the molecule not explicitly considered are classed together as a single dummy terminator (M). Links having two carbon terminators are usually excluded from REX analysis, considerably reducing the total number of links associated with each structure. However, for an analysis of saturated hydrocarbons the links between carbon atoms are included. 

The rate-determining step is the proton capture at the carbon terminal. This process takes place in a concerted fashion with the solvent-induced proton abstraction at the nitrogen terminus to form a diimide that undergoes a loss of N2. 

By definition, a fatty acid is a carboxylic acid that contains twelve or more carbons terminating in a carboxyl group. Because carboxyl groups disassociate at pH above 4-5, free fatty acids occur as negative carboxylate anions (R—COO ) in seawater and marine sediments. Although fatty acid salts are more water-soluble than hydrocarbons. 

Among disubstituted alkenes, tra i -RCH=CHR is normally more stable than ctT-RCH=CHR. Exceptions are cycloalkenes, cis cycloaUcenes being more stable than trans when the ring contains fewer than 11 carbons. Terminally disubstituted alkenes (R2C=CH2) may be slightly more or less stable than RCH=CHR, depending on their snbstitnents. 

In coordination polymerization, monomer forms an adduct with a transition-metal complex, and further monomer is then successively inserted between metal and carbon. Termination occurs when the metal complex splits off from the polymer or the chain is broken intentionally by hydrogenolysis. Since the initiator is restored to its original form, the process is catalytic. The most important industrial processes are Ziegler-Natta polymerizations of a-olefins and employ solid catalysts. Most catalysts for coordination polymerization are hydride complexes of transition metals. An important example is the Shell Higher Olefin Process (SHOP) for homogeneous oligomerization of ethene with a complex nickel catalyst. The molecular-weight distribution is a Schulz-Flory distribution. The rate is first order in the catalyst metal. 

It is very interesting that a resorcinol diol based on propylene carbonate has 85% secondary hydroxyl groups and 15% primary hydroxyl groups. In the resorcinol diols based on propylene carbonate and ethylene carbonate (terminal units), the terminal primary hydroxyl is around 50% [33, 34]. 

Recent developments such as fast phonon-less transitions from carbon-terminated nanocrystals (Dohnalova et al. 2013), fast direct bandgap transitions (Prokofiev et al. 2009 de Boer et al. 2010), and very high values of luminescence quantum efficiencies of silicon nanocrystals in layers (in porous silicon, 23 % (Gelloz et al. 2005 Gelloz and Koshida 2005), and in other assemblies, 18-100 % (Ledoux et al. 2000) and 60 % (Jurbergs et al. 2006)) show that the luminescence of nanocrystalline silicon is progressively paving its way toward applications. 

Tertiary alcohols reportedly reacted and cyclized faster than secondary alcohols. While some primary alcohols were reported to undergo cyclization at the primary carbon, terminal alkenes have provided the intermediate secondary carbocation that cyclized. ... 

In one case (71) a different phenomenon is observed Poly(bisphenol A carbonate) terminated with hydroxyl groups undergoes self-association by hydrogen bonding in solution and these molecular aggregates remain in the sec column. In the application of the sec MALDI method, self-aggregation is suppressed in the sample preparation for the MALDI analysis and thus a very broad molecular mass for each MALDI appears. This is an extreme case where sec alone cannot provide a narrow MMD for MALDI. 

Regio- and Chemoselective Halogenative Cleavage of Epoxides. DBBS very efficiently and regioselectively cleaves terminal epoxides into 1,2-bromohydrins in 15 min in CH2CI2 (eq 21). With the exception of styrene oxide, the transfer of bromine takes place at the less hindered carbon (terminal carbon). In the case of styrene oxide, the bromine is transferred at benzylic position. ... 

A combined approach involving sacrificial synthesis to install the functional focal group and vinyl lactone quenching to install the terminal functionality was also reported. After acidic hydrolysis of the first sacrificial block, hetero-telechelic polyfnorbornene imide)s were generated with either a terminal aldehyde group in the case of vinylene carbonate termination or a terminal carboxylic acid group in the case of 3/f-furanone termination. 

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