Structure, synonyms

Copovidone is manufactured by free-radical polymerization of 6 parts of vinyl-pyrrolidone and 4 parts of vinyl acetate in 2-propanol according to the cGMP regulations. A water-soluble copolymer with a chain structure is obtained (Fig. 89). 

Two commercial products of the vinylpyrrolidone-vinyl acetate copolymer are available in the market having the pharmaceutical quality required by the Pharmacopoeias. Table 151 mentions the tradenames and producers of these copovidone products. 

In contrast to povidone described in Chapter 2 the numbers in the tradenames are not the K-value which characterizes the molecular weight. There is only one type of copovidone in the market having a K-value of the same order of magni- 

The CAS number of the vinylpyrrolidone-vinyl acetate copolymer 6+4 is 25086-89-9. It has the synonyms and abreviations given in Table 152. 

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Technical-grade endosulfan contains at least 94% of two pure isomers, a- and P-endosulfan (Maier-Bode 1968 NRCC 1975). The a- and p-isomers of endosulfan are present in the ratio of 7 3, respectively. Technical-grade endosulfan may also contain up to 2% endosulfan alcohol and 1% endosulfan ether. Endosulfan sulfate is a reaction product found in technical endosulfan it is also found in the environment due to photolysis and in organisms as a result of oxidation by biotransformation (EPA 1979 Coleman and Dolinger 1982). The chemical formula, structure, synonyms, and identification numbers for endosulfan, a-endosulfan, p-endosulfan, and endosulfan sulfate are listed in Tables 3-1, 3-2, 3-3, and 3-4, respectively. 

The chemical formula, structure, synonyms, and identification numbers for trichloroethylene are listed in Table 3-1. 

Mud caps are explosive charges which have a strong destructive effect even when not placed in a confining borehole. They are used for the demolition of boulders and concrete structures. (Synonymous with Adobe Charge and Bulldoze). 

This substance is a mixture of many individual substances and cannot be adequately represented by a single molecular structure Synonyms kanamycin monosulfate 0-3-amino-3-deoxy-a-D-glucopyranosyl-(i-6)-0-[6-amino-6-deoxy-a-D-glucopyranosyl-(i-4)]-2-deo3 -D-streptamine sulfate (1 1) (salt)... 

The two exponential tenns are complex conjugates of one another, so that all structure amplitudes must be real and their phases can therefore be only zero or n. (Nearly 40% of all known structures belong to monoclinic space group Pl c. The systematic absences of (OlcO) reflections when A is odd and of (liOl) reflections when / is odd identify this space group and show tiiat it is centrosyimnetric.) Even in the absence of a definitive set of systematic absences it is still possible to infer the (probable) presence of a centre of synnnetry. A J C Wilson [21] first observed that the probability distribution of the magnitudes of the structure amplitudes would be different if the amplitudes were constrained to be real from that if they could be complex. Wilson and co-workers established a procedure by which the frequencies of suitably scaled values of F could be compared with the tlieoretical distributions for centrosymmetric and noncentrosymmetric structures. (Note that Wilson named the statistical distributions centric and acentric. These were not intended to be synonyms for centrosyimnetric and noncentrosynnnetric, but they have come to be used that way.)... 

Factual databases may provide the electronic version of printed catalogs on chemical compoimds. The catalogs of different suppliers of chemicals serve to identify chemical compounds with their appropriate synonyms, molecular formulas, molecular weight, structure diagrams, and - of course - the price. Sometimes the data are linked to other databases that contain additional information. Structure and substructure search possibihties have now been included in most of the databases of chemical suppliers. 

The CAS Registry contains information on all the chemical compounds published in the literature since 1957. The sources of these 21 million compounds are 9000 international journals containing chemical information. The database includes CAS Registry Numbers, the CAS name (not conforming to the lUPAC convention) with synonyms, and molecular and structural formulas. The CAS provides a weekly update (see Section 5.4). 

The simplest approximation to the complete problem is one based only on the electron density, called a local density approximation (LDA). For high-spin systems, this is called the local spin density approximation (LSDA). LDA calculations have been widely used for band structure calculations. Their performance is less impressive for molecular calculations, where both qualitative and quantitative errors are encountered. For example, bonds tend to be too short and too strong. In recent years, LDA, LSDA, and VWN (the Vosko, Wilks, and Nusair functional) have become synonymous in the literature. 

Structural isomer (Section 1 8) Synonymous with constitu tional isomer... 

In general, replacement prefixes should not be added to heterocyclic parent names, because of the resulting multiplicity of possible synonyms. For example, structure (27) should not be named 2,3,4,6-tetraazaindole or 3,4,6-triazaindazole without very good... 

Chemical Designation - A list of common synonyms is given. Synonym names are alternative systematic chemical names and commonly used trivial names for chemicals. An index of synonyms is provided at the end of the handbook to assist the reader in identifying a particular chemical and researching chemical hazards information in the event that the common name of the chemical is not known. The data field also contains the chemical formula. The chemical formula is limited to a commonly used one-line formula. In the case of some organic chemical compounds it has not been possible to represent the chemical structure within such limitation. 

Antithetic Analysis. (Synonymous with Retrosynthetic Analysis) A problem-solving technique for transforming the structure of a synthetic target molecule to a sequence of progressively simpler structures along a pathway which ultimately leads to simple or commercially available starting materials for a chemical synthesis. 

Chiral Controller. (Synonymous with Chiral Auxiliary). A chiral structural unit which when attached to a substrate enhances stereoselectivity in the formation of new stereocenter(s). 

We have seen that physical properties fail to correlate rate data in any general way, although some limited relationships can be found. Many workers have, therefore, sought alternative measures of solvent behavior as means for correlating and understanding reactivity data. These alternative quantities are the empirical measures described in this section. The adjective empirical in this usage is synonymous with model dependent this is. therefore, an extrathermodynamic approach, entirely analogous to the LFER methods of Chapter 7 with which structure-reactivity relationships can be studied. 

ChemIDplus. Published by the U.S. National Library of Medicine, ChemIDplus [62] is a web-based search system, http //chem.sis.nlm.nih.gov/ chemidplus/, that provides free access to structure and nomenclature authority files used for the identification of chemical substances cited in National Library of Medicine (NLM) databases. ChemIDplus also provides structure searching and direct links to biomedical resources at NLM and on the Internet. The database contains over 349,000 chemical records, over 56,000 of which include chemical structures, and is searchable by name, synonym, CAS registry number, molecular formula, classification code, locator code, and structure. 

Information regarding the chemical identity of hydrogen sulfide is located in Table 3-1. This information includes synonyms, chemical formula and structure, and identification numbers. 

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