Methyl lithium constants

The directly bonded C—coupling constants have been used to give a measure of aromaticity in mono- and polycyclic hydrocarbon ring systems.Cyclo-octatetraene reacts with methylene dichloride and methyl-lithium to afford a mixture of syn and anti-9-chlorobicyclo[6,l,0]nona-2,4,6-triene (40 and 41) which, on treatment with a 30% lithium dispersion in tetrahydrofuran, gives cyclonona-tetraenide, which is isolated as the tetraethylammonium salt. The chemical shift and the coupling constant (7i3c-ih = 137 c./sec.) observed for the lithio-salt (42) are indicative of the aromatic character of the ring, in accord with the predictions of Hiickel s Aromaticity rule. 

Bonds to Carbon.—Phosphorus(jn) Compounds. Force constants, f p = 9.100 mdyn A and/ch = 6.250 mdyn A, have been calculated from an anharmonic force field for HCP. A simple preparative method for trimethyl-phosphine involves the reaction between the trichloride and methyl-lithium in ether at —78 °C and gives yields of ca. 60%. 

The Sign of the Lithium-Carbon Nuclear Spin Coupling Constant in Methyl-lithium Tetramer, W. McFarlane and D. S. Rycroft, J. Organometal. Chem., 64, 303 (1974). 

Table 6.15 shows relative rate constants reported for the addition of methyl-lithium to benzophenone derivatives having the general structure 112 in diethyl ether solution at 0°C. Determine the Hammett p for this reaction. Is the value of p consistent with your expectation for nucleophilic addition of methyllithium to the carbonyl group ... 

Capriati et carried out a B3LYP-DFT/6-311 +- -study of a series of N-H, A-methyl, and A-propyl aziridines and their C-lithium derivatives in order to explore their configurations as well as their and C NMR properties. The Li chemical shifts are not useful probes due to their small range of variation. They calculated /( Li, C) coupling constants and compared them with their measured constants. The experimental V(Li, C) constants were about one third of the calculated ones. The fact that experimental /(Li, C) constants are smaller than the calculated ones is well known.Capriati et therefore calculated the /(Li, C) for methyl lithium. The measured /(Li, Q coupling constant of methyl lithium was 15 Hz in THF, Et20, and EtsN, while the computed /(Li, C) constant was 102.5 Hz in vacuum. They studied the solvent effects on the /(Li, C) for CHsLi using the PCM method. The computed /(Li, C) for CHaLi decreased in solvents 79.0 Hz in toluene and 67.2 Hz in THF. 

Reactions of the Hydroxyl Group. The hydroxyl proton of hydroxybenzaldehydes is acidic and reacts with alkahes to form salts. The lithium, sodium, potassium, and copper salts of sahcylaldehyde exist as chelates. The cobalt salt is the most simple oxygen-carrying synthetic chelate compound (33). The stabiUty constants of numerous sahcylaldehyde—metal ion coordination compounds have been measured (34). Both sahcylaldehyde and 4-hydroxybenzaldehyde are readily converted to the corresponding anisaldehyde by reaction with a methyl hahde, methyl sulfate (35—37), or methyl carbonate (38). The reaction shown produces -anisaldehyde [123-11-5] in 93.3% yield. Other ethers can also be made by the use of the appropriate reagent. 

The electrolyte used in the lithium cell studies was typically 1,2M LiPF6 in ethylene carbonate (EC) propylene carbonate (PC) methyl ethyl carbonate (MEC) in a 3 3 4 mixture. The cells were cycled at room temperature using Maccor Series 4000 control unit in a galvanostatic mode under a constant current density of 0.1 to 1 mA/cm2. 

Step (a) To a 500 mL round bottom flask containing a stir bar was added shell reagent (Y) G = 3.5 methyl ester PAMAM dendrimer, EDA core, (32 g, 2.6 x 10-3 mol, 164 mmol ester, 25 equivalents per core dendrimer (X) and 32 g of methanol. This mixture was stirred until homogeneous. To this mixture was added lithium chloride (7 g, 166 mmol, 1 equivalent per ester) and stirred until homogenous. To this mixture was added (drop-wise) PAMAM dendrimer, EDA core, G = 6 (6 g, 1.0 x 10-4 mol) in 20g of methanol in 10 min. This mixture was warmed to 25 °C and placed in a constant temperature bath at 40 °C for 25 days. 

THF and DME are slightly polar solvents which are moderately good cation solvators. Coordination to the metal cation involves the oxygen lone pairs. These solvents, because of their lower dielectric constants, are less effective at separating ion pairs and higher aggregates than are the polar aprotic solvents. The crystal structures of the lithium and potassium enolates of methyl /-butyl ketone have been determined by X-ray crystal-... 

Rhinebarger et al. [35] and Eyring et al. [36,37] have used lithium-7 nuclear magnetic resonance (NMR) chemical shift data to determine the stability constants for crown-ether complexes of Li+ in two IL systems consisting of 55/45 mole% N-butylpyridinium chloride-aluminum chloride and l-ethyl-3-methyl-imidazolium chloride-aluminum chloride. The stability constants for... 

D. L. Chapman, for potassium tri-iodide. 0. Gropp measured the effect of temp, on the conductivity of solid and frozen soln. of sodium iodide. For the effect of press, on the electrical properties, vide alkali chlorides. A. Reis found the free energy for the separation of the ions of K1 to be 144 lrilogrm. cals, per mol. for iN al, 158 Lil, 153 and for HI, 305. S. W. Serkofi 35 measured the conductivity of lithium iodide in methyl alcohol P. Walden, of sodium iodide in acetonitrile P. Dutoit in acetone, benzonitrite, pyridine, acetophenone. J. C. Philip and H. R. Courtman, B. B. Turner, J. Fischler, and P. Walden of potassium iodide in methyl or ethyl alcohol J. C. Philip and H. P. Courtman in nitromethane P. Dutoit in acetone. H. C. Jones, of rubidium iodide in formamide. S. von Lasczynsky and S. von Gorsky, of potassium and sodium iodides in pyridine. A. Heydweiller found the dielectric constants of powdered and compact potassium iodide to be respectively 3 00 and 5 58. 

Unlike the results calculated for degrees of ionization from the depressions of the f.p., the values of Ostwald s constant computed from the electric conductivities of soln. of rubidium nitrate show marked deviations from constancy and they are thus constant with results with other strong electrolytes—the rubidium ion Rb and the N0V4on are among those with the greatest electro-affinities. The electrical conductivity of lithium nitrate is greater in methyl alcohdl than in water, but in... 

Section II, 1. Theoretical aspects of asymmetric polymerization have been discussed by Fueno and Furdkawa [T. Fueno, J. Furukawa J. Polymer Sci., Part A, 2, 3681 (1964)]. 1-phenyl-l,3-butadiene has been polymerized using (R)-2-methyl-butyl-lithium or butyl-lithium complexed with menthyl-ethyl-ether, yielding optically active polymers with [a] f, referred to one monomeric unit, between +0.71 and —1.79. Optical rotation dispersion between 589 m u and 365 mft is normal and the Drude equation constant is comprised between 255 raft and 280 raft [A. D. Aliev, B. A. Krenisel, T. N. Fedoiova Vysokomol. Soed. 7, 1442 (1965)]. 

Yakushin and Shatenshtein (1960) and Yakushin et al. (1959) have determined the ratio of the rate constants for tritium and deuterium replacement by protium in ammonia solutions of fluorene and methyl 2-naphthyl ketone at 25°. Yakushin has obtained data for these reactions in anhydrous methylamine. Streitwieser et al. (1960, 1962b) have measured the ratio fcD/ T for the hydrogen exchange of ethylbenzene and toluene catalysed by a solution of lithium cyclohexylamide in cyclohexylamine at 49-9°. 

Thermodynamic functions (entropy, heat capacity, enthalpy and free energy functions) have not been reported for 1,2,4-thiadiazoles. The ionization constants of a number of 1,2,4-thiadiazoIes have been determined potentiometrically or by Hammett s method (65AHC(5)ll9). Polarographic measurements of a series of methylated 5-amino-l,2,4-thiadiazoles show that thiadiazoles are not reducible in methanolic lithium chloride solution, while thiadiazolines are uniformly reduced at E0.s = -1.6 0.02 V. This technique has been used to assign structures to compounds which may exist theoretically as either thiadiazoles or thiadiazolines (65AHC(5)119). 

Interestingly, no correlation could be observed from their monomer ion-pair acidities (pAT0 in THF) and the second-order rate constant for the monomer in their reaction with m-chlorobenzyl bromide (Table 2, right), a linear relationship occurs when the corresponding cesium salts are alkylated with methyl tosylate. On the other hand according to the authors, this accounts for the fact that the lithium cation is as important as the basicity of the enolate. 

Closely related to these investigations, Breslow and co-workers studied the Diels-Alder reaction of CP with methyl vinyl ketone (MVK) in water-like solvents, ethylene glycol and formamide, in the presence of lithium salts. They found clear differences and similarities between water and these two solvent systems. In the absence of Li salts, the second-order rate constant for the reaction at 20 °C increased in formamide ( 2 = 3184 X 10 m s" ), and even more in ethylene glycol (480 x 10 m" s" ), relative to a polar solvent such as methanol (75.5 x 10 m" s ) or non-polar solvent such as isooctane (5.940.3 x 10 m s ). The reactions in both polar solvents were faster in the presence of LiC104 than in the presence of LiCl, although the perchlorate ion has less salting-out effect than chloride ion in water [41]. 

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