Spectroscopic data

Beilstein provides a great deal of information on spectra, e.g. IR, Mass and NMR spectra. Moreover, the database Specinfo is directly accessible from Beilstein, i.e. one can retrieve spectra there without a change of file  

2 Wulf. Liddel. J Amer Chem Soc. 57 1935 1464.1468. CODEN- JACSAT Note(s) 

1 Lutskii et al.. J Gen Chem USSR (Engl.Transl.). 46 1976 , 2238, CODEN JGCHA4 

Watabe. Nippon Kagaku Kaishi. 1972 . 225. CODEN NKAKB8 

Chemical Name (CN) 4 -HYDR0XYACET0PHEN0NE Other Source (OS) Specinfo Database Document No (DN)- STCC-57477-413 Data Type (DATA) 0-NMR-spectrum Reference(s) 

The 111 NMR, 13C NMR (NMR - nuclear magnetic resonance), infrared (IR), ultraviolet (UV), and mass spectrometry (MS) data have been reported for the first example 5 of a 2/7-azepin-2-one (2-azatropone). The carbonyl group stretching frequency appeared at 1682 cm 1 in the IR spectrum of the neat material 2000JOC6093 . Further H and 13C NMR spectroscopic data on azepine derivatives have been summarized by Smalley 1997HOU(E9d)108 . 

A conformational study of novel polyhydroxylated azepanes has been reported in which the 1H NMR spectroscopy and molecular modeling (molecular mechanics, molecular dynamics, and Monte Carlo methods) afforded insights into aspects of the conformational analysis 2004EJ04119 . 

In the electronic absorption spectra of Sm and Ho allyl complexes in THF solutions a new band appears (513 and 425 nm respectively). This band is absent in the spectra of related compounds Cp2LnCl and is not observed in the spectra of allyl derivatives of lanthanoids dissolved in benzene. The interaction between THF and the delocalized 7C-system of allyl ligand is considered to be one of the possible reasons for appearance of aforementioned bands [17], 

Gailunas G.A., Biktimirov R. Kh., Khairullina R.M., Tolstikov G.A., Dokl. Akad. Nauk. SSSR, (Russ.), 295 (1987) 1385. 

Brunelli M., Poggio S., Pedretti U., Lugli G., Inorg. Chim. Acta, 131 (1987) 281. 

The electronic spectrum of PPV has been studied in detail by Obrzut et al. [170]. The infrared spectra of stretch oriented PPV have been recorded and widely studied by Bradley et al. [171] who have also studied the infrared spectra of doped [172] and pohotoexcited materials [173]. 

Raman spectra of pristine PPV with Aexc 676.4 and 351.1 nm are reported by Lefrant et al. [174]. The same group has reported the Raman spectrum of doped PPV and have derived some structural information [174]. As discussed in section 4 there are some theoretical reasons to believe that the observation of the Raman spectra of doped polyconjugated materials is doubtful. This problem is going to be 

The electronic spectra of the oligomers have been reported by Drefahl et al [168] We have recorded the UV-Vis spectra of t-bytyl capped oligomers ( solid and CH2CI2 solutions) of the general formula (t-butyl)2[-0-CH=CH-(0-CH=CH)) -0-(t-butyl) 2 with n =1 to 5 (hereafter referred as Oj ). 

We have also recorded and studied the vibrational infrared spectra and the Fourier Transform Raman spectra at Aexc =10 0 series of 6j oligomers [175 176). 

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Considerable spectroscopic data are required for the detemiination of the relative populations in die various internal quantum levels of the product from the relative intensities of various lines, or bands, in a spectrum. 

Van der Waals complexes can be observed spectroscopically by a variety of different teclmiques, including microwave, infrared and ultraviolet/visible spectroscopy. Their existence is perhaps the simplest and most direct demonstration that there are attractive forces between stable molecules. Indeed the spectroscopic properties of Van der Waals complexes provide one of the most detailed sources of infonnation available on intennolecular forces, especially in the region around the potential minimum. The measured rotational constants of Van der Waals complexes provide infonnation on intennolecular distances and orientations, and the frequencies of bending and stretching vibrations provide infonnation on how easily the complex can be distorted from its equilibrium confonnation. In favourable cases, the whole of the potential well can be mapped out from spectroscopic data. 

Over the next few years, both the mid-infrared and the far-infrared spectra for Ar-HF and Ar-HCl were extended to numerous other bands and to other isotopic species (most importantly those containing deuterium). In 1992, Hutson [18, 39] combined all the available spectroscopic data to produce definitive potential energy surfaces that included both the angle dependence and the dependence on the HF/HCl monomer vibrational quantum number v... 

Hush N S 1967 Intervalence-transfer absorption. Part 2. Theoretical considerations and spectroscopic data Prog. inorg. Chem. 8 391... 

Chemical properties and spectroscopic data support the view that in the elements rubidium to xenon, atomic numbers 37-54, the 5s, 4d 5p levels fill up. This is best seen by reference to the modern periodic table p. (i). Note that at the end of the fifth period the n = 4 quantum level contains 18 electrons but still has a vacant set of 4/ orbitals. 

Chemical, physical and spectroscopic data all suggest a periodic table as shown on p. (/T. 

The large databases CA, Betlstein, and Gmelin do not provide methods for directly searching spectroscopic data. Detailed retrieval of spectroscopic information is provided in databases that contain one or more types of spectra of chemical compounds. Section 5.18 gives an ovei view of the contents of larger databases including IR, NMR, and mass spectra. 

Specinfo, from Chemical Concepts, is a factual database information system for spectroscopic data with more than 660000 digital spectra of 150000 associated structures [24], The database covers nuclear magnetic resonance spectra ( H-, C-, N-, O-, F-, P-NMR), infrared spectra (IR), and mass spectra (MS). In addition, experimental conditions (instrument, solvent, temperature), coupling constants, relaxation time, and bibliographic data are included. The data is cross-linked to CAS Registry, Beilstein, and NUMERIGUIDE. 

This database has some additional commands and search fields, which are tailored to the specific requirements of retrieving spectroscopic data, e.g., peak or multiplicity searches. 

Robust implementations can currently propose correct structures from spectroscopic data, especially when the molecular formula and C NMR spectrum are available, or from 2D NMR spectra. 

Characteristic spectroscopic data (infrared and NMR) of 2-thiazolyl ureas are given in a recent report (484). Their characteristic ultraviolet absorption is in the 260 to 270 nm region (487). 

The following tables contain information on 6000 aminothiazoles. Letters placed after each reference indicate whether any applications or spectroscopic data are given in the reference (meaning of the letters is given in Part One, pp. 2 and 3. Some confusion may occur when the letter 1 (living material) is placed after the reference because of the typographic similarity of one and ell. Be cautious and don t mix up for example 1131 and 113 1. 

The synthesis of other A-2-thiazolin-4-ones has been reported (414. 424. 429. 436-439). However, insufficient spectroscopic data are given to show if their structures are monomeric or polymeric. 

To sum up, spectroscopic data indicate the amino" form (10) is predominant when R is a hydrogen atom or an alkyl group, while the imino form (11) is predominant when R is an aryl group (Scheme 66). 

Molar absorptivity when measured at X x is cited as e ax It is normally expressed without units Both X x and Cmax are affected by the solvent which is therefore included when reporting UV VIS spectroscopic data Thus you might find a literature reference expressed m the form... 

Figure 13 49 presents several types of spectroscopic data (IR H NMR C NMR and mass spectra) for a particular compound What is it" ... 

The entropy value of gaseous HCl is a sum of contributions from the various transitions summarized in Table 4. Independent calculations based on the spectroscopic data of H Cl and H Cl separately, show the entropy of HCl at 298 K to be 186.686 and 187.372 J/(mol K) (44.619 and 44.783 cal/(mol K), respectively. The low temperature (rhombic) phase is ferroelectric (6). SoHd hydrogen chloride consists of hydrogen-bonded molecular crystals consisting of zigzag chains having an angle of 93.5° (6). Proton nmr studies at low temperatures have also shown the existence of a dimer (HC1)2 (7). 

Boron tnhahdes, BX, are trigonal planar molecules which are sp hybridized. The X—B—X angles are 120°. Important physical and thermochemical data are presented in Table 1 (8—14). Additional thermodynamic and spectroscopic data may be found in the hterature (1 5). 

Cyanuric acid is a titrable weak acid (pffai — 6.88, pifa2 — H-40, pffas — 13.5) (10). The pH of a saturated aqueous solution of pure CA at room temperature is - 4.8. Thermodynamic properties of CA are given ia Table 1. Spectroscopic data are available (1 3). Proton nmr is of limited usefulness because of proton exchange and CA s symmetry and low solubiUty. Nuclear quadmpole resonance measurements ( " N) have been reported (12). 

Perhaps the most firmly based report for the formation of an azete involves flash pyrolysis of tris(dimethylamino)triazine (303). This gave a red pyrolysate believed to contain the highly stabilized azete (304) on the basis of spectroscopic data. The putative azete decomposed only slowly at room temperature, but all attempts to trap it failed (73AG(E)847). Flash pyrolysis of other 1,2,3-triazines gives only acetylenes and nitriles and it is not possible to tell whether these are formed by direct <,2-l-<,2-l-<,2 fragmentation of the triazine or by prior extrusion of nitrogen and collapse to an azete (81JCR(S)162). 

One apparent discrepancy between the spectroscopic data and the crystal structure is that no spectroscopic signal has been measured for participation of the accessory chlorophyll molecule Ba in the electron transfer process. However, as seen in Figure 12.15, this chlorophyll molecule is between the special pair and the pheophytin molecule and provides an obvious link for electron transfer in two steps from the special pair through Ba to the pheophytin. This discrepancy has prompted recent, very rapid measurements of the electron transfer steps, still without any signal from Ba- This means either... 

Especially detailed study of the mechanism of photochemical configurational isomerism has been done on Z- and A-stilbene." Spectroscopic data have established... 

Although the nature of the general polar effect suggested by Kamernitzsky and Akhrem " to account for axial attack in unhindered ketones is not clear, several groups have reported electrostatic interactions affect the course of borohydride reductions. Thus the keto acid (5a) is not reduced by boro-hydride but its ester (5b) is reduced rapidly further, the reduction of the ester (6b) takes place much more rapidly than that of the acid (6a). Spectroscopic data eliminate the possibility that in (5a) there is an interaction between the acid and ketone groups (e.g. formation of a lactol). The results have been attributed to a direct repulsion by the carboxylate ion as the borohydride ion approaches. " By contrast, House and co-workers observed no electrostatic effect on the stereochemistry of reduction of the keto acid (7). However, in this compound the acid group may occupy conformations in which it does not shield the ketone. Henbest reported that substituting chlorine... 

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