Dimethylformamide calculations

However, the iodo-substituent, which might be expected to show similar behavior, is well behaved. The behavior of the substituents MeSO, SCF3, and CF3SO would be instructive in this connection, but no data exists for these substituents in any of the sets. The substituents NHCOMe and OCgHs, which involve competing conjugative interaction mechanisms, as well as coplanarity problems, are only moderately well behaved in the sets. Calculated values of vary from —.74 to -.86 for the former and -.74 to -.92 for the latter. There is, however, a considerable presumption in the case of the NHCOMe substituent that this behavior is solvent related. The value —.74 (reaction 6) is obtained in water solvent at 25°, and the value —.86 (reaction 23) is obtained in dimethylformamide solvent at 17°. The 0/j(ba) values calculated for the NHCOMe substituent show similar trends with solvent, as shown in Table XVI. 

Fig. 39.—Plots of c/c against c from the data of Masson and Melville for the following solvent-polymer pairs curve 1, polyacrylonitrile in dimethylformamide at 13.5° C curves 2 and 4, poly-(vinyl acetate) s in benzene at 20°C curve 3, polyacenaphthylene in benzene at 25°C curve 5, polyvinylxylene in benzene at 24°C curve 6, poly-(methyl methacrylate) in benzene at 16°C. All curves have been calculated from Eq. (13). Units correspond to those in Fig. 38. (Fox, Flory, and Bueche. )...

I, 4 in hydrocarbons to 2 in pyridine (3 - 11,0) and again decreases to 1,5 in alcohols. Calculated on this basis value 3 of coal increases droningly with increasing the content of carbon from 70 % till 87 % and in a case of more metamorphized coal is sharply decreased again. Data concerning to the extraction of Greta coal are evidence of maximal yield of extract (more than 20 %) under it treatment with ethylendiamine and dimethylformamide (3 -... 

A different electrochemical approach was applied to the cathodic reduction of sulfones in W,JV-dimethylformamide (Djeghidjegh et al., 1988), for example t-butyl phenyl sulfone, which is reduced at a more negative potential ( pc = -2.5 V) than is PBN (-2.4 V). Thus, the electrolysis of a mixture of PBN and the sulfone would possibly proceed via both true and inverted spin trapping. If a mediator of lower redox potential, such as anthracene (-2.0 V), was added and the electrolysis carried out at this potential, it was claimed that only the sulfone was reduced by anthracene - with formation of t-butyl radical and thus true spin trapping was observed. It is difficult to see how this can be reconciled with the Marcus theory, which predicts that anthracene - should react preferentially with PBN. The ratio of ET to PBN over sulfone is calculated to be 20 from equations (20) and (21), if both reactions are assumed to have the same A of 20 kcal mol-1. 

Po Polarity, Xe proton acceptor, Xd proton donor, Xn dipole moment, THF tetrahydrofuran, ACN acetonitrile, MeOH methanol, ATN acetone, DMF dimethylformamide, nc cannot be calculated. 

The outer-sphere one-electron reduction of CO2 leads to the formation of the 02 radical anion. In dry dimethylformamide, the C02/ C02 couple has been experimentally determined to be —2.21 V vs. standard calomel electrode (SCE) or approximately —2.6 V vs. the ferrocene/ferrocenium couple [21,22]. From pulse radiolysis experiments, the reduction potential of CO2 is —1.90 V vs. the SHE in water (—2.14 V vs. SCE) [23]. Theoretical calculations have been used to calculate the contributions of various factors to the reduction potential of CO2. These include the electron affinity of CO2,... 

Electronic absorption studies were performed on compounds 90 and 91 in dimethylformamide (DMF) the longest wavelength maxima at 503-567 nm arising from intramolecular charge transfer (ITC) are shifted bathochromically with an increase in the sum of the nucleophilic constant btt-attached to the fluorene ring. An equation to enable calculation of this effect was devised <2001MM2232>. 

Crosslink density of PU films. The PU films were subjected to swelling tests in dimethylformamide. The crosslink densities of the films were thereafter estimated from equilibrium swelling data using a modified version of the Flory-Rehner equation. The swelling tests as well as the calculation of crosslink density are described in detail in a previous paper (6). 

Freshly made amino acid solutions are recommended for peptide synthesis, although stock solutions of /V -Fmoc-AAs (A-fluorenylmethoxycar-bonyl a-amino acids) with HOBt in DMF (/V,/V-dimethylformamide) can be stored at 4° for a week. Since the synthesis of a hexapeptide or octapep-tide library usually takes only 2-3 days, all the amino acid solutions may be prepared before the synthesis. A 3-fold excess of Aa-Fmoc-AAs is needed in each couphng step to ensure completion of the coupling reaction. We have been using the following equations to calculate the amount of necessary reagents. 

Another example where aromaticity plays an important role is the barrier to the rotation of amides (compound 18 is represented with N in the middle to indicate any azole) [31]. In classical amides, like dimethylformamide (15), the calculated barrier is 80.1-81.0 kJ mol1 (MP2/6-311++G ), which compares well with the experimental barriers of 91.2 (solution) and 85.8 kJ mol1 (gas-phase) [32], The cases of A-formylaziridine (16) and iV-formyl-2-azirine (17) are more complex due to the pyramidalization of the nitrogen atom and the presence of rotation and inversion barriers [32], The effect of the antiaromatic character of 2-azirine (four electrons) [18] on the barrier is difficult to assess due to changes in the ring strain. 

Capello et al.16 applied LCA to 26 organic solvents (acetic acid, acetone, acetonitrile, butanol, butyl acetate, cyclohexane, cyclohexanone, diethyl ether, dioxane, dimethylformamide, ethanol, ethyl acetate, ethyl benzene, formaldehyde, formic acid, heptane, hexane, methyl ethyl ketone, methanol, methyl acetate, pentane, n- and isopropanol, tetrahydrofuran, toluene, and xylene). They applied the EHS Excel Tool36 to identify potential hazards resulting from the application of these substances. It was used to assess these compounds with respect to nine effect categories release potential, fire/explosion, reaction/decomposition, acute toxicity, irritation, chronic toxicity, persistency, air hazard, and water hazard. For each effect category, an index between zero and one was calculated, resulting in an overall score between zero and nine for each chemical. Figure 18.12 shows the life cycle model used by Capello et al.16... 

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