Structures of organic compounds

The crystal structure of acetylene, C2H2, is cubic with four molecules per cell, Tjj, Pa3, a0 = 6.14 A at —117°C. This corresponds to a ccp or face-centered cubic structure or 3P. 

The Body-Centered [3 2PTOT(o)l Crystal Structure of Ethylene 

The Crystal Structures (Body-Centered and ccp Types) of Tetrakis(hydroxymethyl)methane, C(CH2OH)4 

For metals and some other solids transformation from ccp to bcc, or reverse, under different conditions, is common. It is less common among molecular solids, but this example indicates that these transformations are generally applicable. 

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Figure 2-67. Classification of isomeric structures of organic compounds.

Braude, Ultra-Violet Light Absorption and the Structure of Organic Compounds Annual Reports, 42, 105 (1945). ... 

Before the advent of NMR spectroscopy infrared (IR) spectroscopy was the mstrumen tal method most often applied to determine the structure of organic compounds Although NMR spectroscopy m general tells us more about the structure of an unknown com pound IR still retains an important place m the chemist s inventory of spectroscopic methods because of its usefulness m identifying the presence of certain functional groups within a molecule... 

J. B. Pedley, Thermochemical Data and Structures of Organic Compounds, (Thermodynamics Research Center, College Station, TX, 1994). 

Molecular Orbital Theory of the Electronic Structure of Organic Compounds V Molecular Orbital Theoiy of Bond Separation W. J. Hehre, R. Ditchfield, L. Random and J. A. Pople Journal of the American Chemical Society 92 (1970) 4796... 

This powerful system maximizes the students learning experience and, at the same time, reduces faculty workload and helps facilitate instruction. OWL also uses the MDL Chime application to assist students with viewing structures of organic compounds. New to this edition are 15 to 20 end-of-chapter problems per chapter, denoted by a icon, which are assignable in OWL. A fee-based access code is required for OWL. 

Mass spectrometry can be used for gas analysis, for the analysis of petroleum products, and in examining semiconductors for impurities. It is also a very useful tool for establishing the structure of organic compounds. 

C. Affolter and J.T. Clerc, Prediction of infrared spectra from chemical structures of organic compounds using neural networks. Chemom. Intell. Lab. Syst., 21 (1993) 151-157. 

Nakanisi, K. IR Spectra Structure of Organic Compounds, Moscow, Mir Publishers, 1965, (Russ. Transl.)... 

For even more convenience in representing the structures of organic compounds, particularly in printed material, line formulas are used, so-called because they are printed on one line. In line formulas, each carbon atom is written on a line adjacent to the symbols for the other elements to which it is bonded. Line formulas show the general sequence in which the carbon atoms are attached, but in order to interpret them properly, the permitted total bond orders of all the respective atoms must be kept in mind. Again referring to the compounds (a) to (e) described above, the line formulas are as follows ... 

Vishveshwara, S., and J. A. Pople. 1977. Molecular Orbital Theory of the Electronic Structures of Organic Compounds. 32. Conformations of Glycine and Related Systems. J. Am. Chem. Soc. 99, 2422-2426. 

A type of spectroscopy used in chemical analysis and the determination of the structure of organic compounds and polymers. 

The importance of ultraviolet absorption spectroscopy as a tool for the elucidation of the chemical structure of organic compounds is well established. Although it has been extensively used in lignin research, as yet definite conclusions have not been attained. 

FIGURE 1.1 Structures of organic compounds referred to in the text (a) sucrose (also known as saccharose), (b) dimethyl sulfoxide (DMSO), (c) dimethylformamide (DMF), (d) sorbitol, (e) mannitol, (f) nitrilotriacetic acid (NTA), (g) citric acid, (h) N,N,N, N -fran,s-1,2-diaminocyclohexane-tetraacetic acid (CyTA), (i) saccharic acid, (j) glutamic acid. 

The structural chemistry of dienes and polyenes is extremely diverse and intricate since about 12% of all determined structures of organic compounds contain two or more double... 

Fig. 2 Chemical structure of organic compounds identified in paper mill effluents...

In qualitative analysis. The study provides an evidence in the elucidation of structures of organic compounds. For example, if there is no appreciable absorption in the region 270 to 280 nm, then the compound does not contain a benzene ring. 

The choice of a given database as source of auxiliary values may not be straightforward, even for a thermochemist. Consistency is a very important criterion, but factors such as the publication year, the assignment of an uncertainty to each value, and even the scientific reputation of the authors or the origin of the database matter. For instance, it would not be sensible to use the old NBS Circular 500 [22] when the NBS Tables of Chemical Thermodynamic Properties [17], published in 1982, is available. If we need a value for the standard enthalpy of formation of an organic compound, such as ethanol, we will probably prefer Pedley s Thermodynamic Data and Structures of Organic Compounds [15], published in 1994, which reports the error bars. Finally, if we are looking for the standard enthalpy of formation of any particular substance, we should first check whether it is included in CODATA Key Values for Thermodynamics [16] or in the very recent Active Thermochemical Tables [23,24],... 

The primary source of information for enthalpies of formation is J. B. Pedley, R. D. Naylor and S. P. Kirby, Thermochemical Data of Organic Compounds (2nd Ed.), Chapman Hall, New York, 1986. The successor to this volume, J. B. Pedley, Thermochemical Data and Structures of Organic Compounds, Vol. I, Thermodynamics Research Center, College Station, Texas, USA, 1994, has recently been published. We have used values from this latter source when the compounds were not included in the earlier edition. In any case, no reference citation is given except for occasionally referring to either volume as Pedley or merely archival . Where data were... 

C nuclei has become a powerful tool for elucidation of the structures of organic compounds. A large number of textbooks, monographs, articles, and data collections (1-15) deal with this method, and individual reviews have been devoted to practically all classes of natural products and related organic compounds (lb-24). 

This series of volumes, established by Victor Gold in 1963, aims to bring before a wide readership among the chemical community substantial, authoritative and considered reviews of areas of chemistry in which quantitative methods are used in the study of the structures of organic compounds and their relation to physical and chemical properties. 

Pedley provides group values and the experimental data from which they have been derived. J. Pedley, Thermochemical Data and Structure of Organic Compounds-Vol. /, TRC Data Series, CRC Press, Boca Raton, FL, 1994. 

The 5 major spectroscopic methods (MS, UV, IR, H NMR and NMR) have become established as the principal tools for the determination of the structures of organic compounds, because between them they detect a wide variety of structural elements. 

DETERMINiNG THE STRUCTURE OF ORGANiC COMPOUNDS FROM SPECTRA... 

Chapter 8 Determining the Structure of Organic Compounds from Spectra... 

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