Acetonitrile structure

J. VandeVondele, R. Lynden-Bell, E. J. Meijer, and M. Sprik (2006) Density functional theory study of tetrathiafulvalene and thianthrene in acetonitrile structure, dynamics and redox properties. J. Phys. Chem. B 110, p. 3614... 

Vitale, G., Valina, A.B., Huang, H. et al. (2001) Solvation of copper ions by acetonitrile. Structures and sequential binding energies of Cu+(CH3CN)j , x = 1-5, from coUision-induced dissociation and theoretical studies. J. Phys. Chem. A, 105, 11351-11364. 

Hajdu (27) has presented spectroscopic and electrochemical evidence for the formation of 1 1 complexes of streptonigrin with Cu and Zn" in each case with the release of one equivalent of proton. The pKa of streptonigrin was lowered 2.3 and 3.3 pKa units in the presence of one equivalent of Zn and Cu, respectively. In acetonitrile solution, reduction of streptonigrin was accelerated in the presence of Cu but was inhibited by Zn. Hajdu suggested that in acetonitrile structure... 

Aziridines represented by the general structure (458 X = 0, S, NR) undergo a facile ring opening and subsequent closure on heating with sodium iodide in acetone or acetonitrile. For (458 X = O) the oxazoline (460) was formed, presumably via the intermediate (459) (66JOC59). 

The esters of thiosulfinic acid R -SO,-S-R are used as fungicides and antibacterial prepai ations. These compounds have similar stiaicture fragments to allicin - natural insecticide from garlic with following structure (CH =CH-CH ),[SO-S] (http //www.ALLICIN.com). For deter-mination of ethyl S-ester of 4-aminobenzenthiosulfinic acid (esulan) in the ointment RP-HPLC was proposed [1] with acetonitrile water=30 70 as eluent. For seai ching bioactive compounds the synthesis of new esters of thiosulfinic acid is perspective that was confirmed by results of recent studies as instance [2]. Therefore requirements ai e existed for investigation HPLC sepai ations of these substances. 

The principal components of the cut are butene-1, butene-2, isobutylene and butadiene-1,3. Methyl, ethyl, and vinyl acetylenes, butane and butadiene-1,2 are present in small quantities. Butadiene is recovered from the C4 fraction by extraction with cuprous ammonium acetate (CAA) solution, or by extractive distillation with aqueous acetonitrile (ACN). The former process is a liquid-liquid separation, and the latter a vapor-liquid separation. Both take advantage of differences in structure and reactivity of the various C4 components to bring about the desired separation. 

Photoelectron spectra have confirmed the expected trends in the frontier orbitals.The tetrafiuoro derivative 12.12 (R = F) is prepared by treatment of C6F5SNSNSiMc3 with CsF in acetonitrile (Scheme 12.2). Several difiuoro- and trifiuoro-benzodithiadiazines have also been prepared by these methods.In contrast to 12.12 (R = H), which has an essentially planar structure in the solid state,the dithiadiazine ring in the tetrafiuoro derivative is somewhat twisted. In the gas phase, on the other hand, electron diffraction studies show that 12.12 (R = F) is planar whereas 12.12 (R = H) is non-planar. ... 

These rate constants are for the cinnamoylation of hydroxy compounds by cinnamic anhydride catalyzed by A-methylimidazole. The reaction is first-order in each reactant. The kinetics were followed spectrophotometrically in acetonitrile solution. Analyze the data that is, attempt to account for the relationship between structure and reactivity. 

An earlier report (126) which assigned the irons configuration to the enamine (175) derived from the cyanamine (176) upon reaction with potassium amide in liquid ammonia has been questioned by Munk and Kim (725). They also have doubts about the structures (177 and 178) proposed for the products obtained by the reduction of acetonitrile with sodium (727). 

The reaction between the pyrrolidine enamine of butyraldehyde (52) and )3-nitrostyrene (53) provides cyclobutane adduct 54 quantitatively in either petroleum ether or acetonitrile solvent, but in the more polar ethanol solvent a 2 1 condensation product occurred. The structure of the product was shown to be 55 (57). 

Next, we will consider the vibrational frequencies of formaldehyde in acetonitrile, using the Onsager SCRF model and the SCIPCM model. Acetonitrile is a highly polar solvent, with an e value of 35.9. In order to predict the vibrational frequencies, we ll first need to optimize the structure for formaldehyde in this medium. Thus, we ll be running these jobs ... 

The volume calculation results in a cavity radius of 3.65. The acetonitrile solution produces only subtle changes in the molecule s structure. The only significant change is a decrease of 0.3-0.4° in the O-C-H bond angle. 

Sclutlcn The geometry optimization reveals that the structure of formaldehyde in cyclohexane is essentially the same as it is in acetonitrile. Here are the predicted frequency shifts with respect to the gas phase for the two media ... 

The structure of 82 was established by alkaline ring cleavage to benzilic acid amide and by hydrogenolysis to (C6H5)2CH—CONH— COCfiHs. These reactions also served to eliminate 83 as the structure of the 169° compound. The other possible isomeric structure, (C6H5)2C(CN)0C0C6H5, which could have formed after 0-acylation, was ruled out by its independent synthesis from bromodiphenyl-acetonitrile and silver benzoate. 

Pyridyl)benzothiazole with [Re(CO)5X] (X = Cl, Br) forms the chelate structures 18 (X = C1, Br) (01ICA(314)91). With silver triflate, dehalogenation occurs followed by formation of 18 (X = OTf). The latter refluxed in acetonitrile gives the cationic complex of stoichiometry [Re(CO)3L(AN)](OT0-... 

Feng et al. [3] have studied the structural effect of acetanilide on the AAM polymerization either in water-for-mamide [3], water-acetonitrile [4], and water-DMF [26] mixed solution using Ce(IV) ion-acetanilide and its substituted derivatives as the initiator. The results showed that an electron donating substituent on the phenyl group would enhance the Rp, while an electron withdrawing group would decrease it, as shown in Table 1 [26]. 

Draw an electron-dot structure for acetonitrile, C2H3N, which contains a carbon-nitrogen triple bond. How many electrons does the nitrogen atom have in its outer shell How many are bonding, and how many are non-bonding ... 

Draw a resonance structure of the acetonitrile anion, - CH2C=K, and account for the acidity of nitriles. 

Fig. 9.3 Absorption spectra of panal in methanol (A), and in 18% acetonitrile/water (v/v) containing 20mM morpholine and acetic acid, pH 4.3 (B). The absorption peak in A is broad due to the partial enolization of the keto group forming a conjugated structure C=C-C=C-OH. In B, the C=0 group is completely converted into an enamine (C=C-C=C-NR2) by morpholine, giving a sharp absorption peak. From Shimomura, 1989, with permission from the American Society for Photobiology.

Both PS-A and PS-B have a tendency to hydrate like panal, and they also form adducts with methylamine. The adducts, PS-A/MA and PS-B/MA, are prepared by incubating PS-A or PS-B in 75 % methanol containing an excess amount of methylamine hydrochloride plus some sodium acetate to neutralize the HC1, at 45°C for 30 min. The adducts can be purified by HPLC on a PRP-1 column (80% acetonitrile containing 0.05% acetic acid). Their chemical structures have been determined by NMR and mass spectrometry as shown in Fig. 9.8 (p. 288). Both adducts are colorless and show an absorption maximum at 218 nm. 

Properties of luciferin precursors. About one dozen of the luciferin precursors of M. citricolor isolated by HPLC had a strong tendency of isomerization, as mentioned above. Their molecular weights could not be established by mass spectrometry, which is probably due to isomerization, although they appear to be in a range of 300-600. The precursors showed an absorption peak at about 369 nm in methanol and aqueous acetonitrile (Fig. 9.13). According to an NMR study, all precursors probably contain the following common partial structure (personal communication from Dr. H. Nakamura, 1998). 

Add 100 pi 1 of MSTFA reagent to less than 1 mg of dry extract. Heat at 60° for 15-20 min. If necessary, add 250 /a 1 of acetonitrile or other suitable solvent. For additional structural information, prepare the methoxime-TMS derivative to determine if one or more carbonyl groups are present. 

The reactivities of the various phosphinyl radicals with monomers have been examined (Table 3. lO).283-465,467-475 Absolute rate constants are high, lying in the range 106-I08 M 1 s 1 and show some solvent dependence. The rate constants are higher in aqueous acetonitrile solvent than in methanol. The high magnitude of the rate constants has been linked to the pyramidal structure of the phosphinyl radicals.46- ... 

Finally, an example of an x-ray structure of a cationic complex shall be mentioned. From the data for 12, a surprisingly weak coordination (Si —N 1.932(8) A [146, 147]) of the acetonitrile donor to the silicon is inferred. The deviation from a pure tetrahedral geometry at the silicon is the largest yet observed (Table 4). 

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