AMPAC

One very popular technique is an adaptation of the Born model for orbital-based calculations by Cramer and Truhlar, et. al. Their solvation methods (denoted SMI, SM2, and so on) are designed for use with the semiempirical and ah initio methods. Some of the most recent of these methods have a few parameters that can be adjusted by the user in order to customize the method for a specific solvent. Such methods are designed to predict ACsoiv and the geometry in solution. They have been included in a number of popular software packages including the AMSOL program, which is a derivative of AMPAC created by Cramer and Truhlar. 

AMPAC (we tested Version 6.51) is a semiempirical program. It comes with a graphic user interface (we tested Version 6.0). The documentation included with the package is well written. 

AMPAC can also be run from a shell or queue system using an ASCII input file. The input file format is easy to use. It consists of a molecular structure defined either with Cartesian coordinates or a Z-matrix and keywords for the type of calculation. The program has a very versatile set of options for including molecular geometry and symmetry constraints. 

GaussView (we used Version 2.08) is a graphic interface for use with the Gaussian ah initio program. It can be used to build molecules, set up the options in the input hie, run a calculation, and display results. GaussView uses the molecule builder that was written by SemiChem, but has screens for setting up calculations that are different from those in the AMPAC GUI sold by SemiChem. 

CODESSA reads molecular structure files or output files created by other software packages as the starting point for QSAR analysis. It can import computational results from AMPAC, MOPAC, and Gaussian as well as structures in a number of common formats. 

American Council on Science and Health (ACSH), 278 American Crop Protection Association (ACPA), 267, 278 American Cyanamid Agricultural Products Division, See BASF Agricultural Products Group (US), 216 American Fiber Manufacturers Association, hic. (AFMA), 268 American Hydrogen Association (AHA), 268 American Industrial Hygiene Association (AIHA), 278 American Institute of Chemical Engineers (AICHE), 268 American Institute of Chemists, The (AIC), 268 American Methanol Institute (AMI), 268 American Oil Chemists Society (AOCS), 268 American Ordnance LLC, 216 American Pacific Corporation (AMPAC), 216 American Peptide Society (APS), 268... 

Semi-empirical methods, such as AMI, MINDO/3 and PM3, implemented in programs like MOPAC, AMPAC, HyperChem, and Gaussian, use parameters derived from experimental data to simplify the computation. They solve an approximate form of the Schrodinger equation that depends on having appropriate parameters available for the type of chemical system under investigation. Different semi-emipirical methods are largely characterized by their differing parameter sets. 

Semi-empirical methods are characterized by their use of parameters derived from experimental data in order to simplify the approximation to the Schrbdinger equation. As such, they are relatively inexpensive and can be practically applied to very, very large molecules. There are a variety of semi-empirical methods. Among the best known are AMI, PM3 and MNDO. Gaussian includes a variety of semi-empirical models, and they are also the central focus or present in many other programs including AMPAC, MOPAC, HyperChem and Spartan. 

More recent examples include Ampac Fine Chemicals (AFC) in California, who implemented a multipurpose continuous small-scale plant for the production of several hundred tons of API per year [31], and Sigma-Aldrich s Fine Chemicals, which has been adding continuous-process technology within its Buch facility [32]. 

SemiChem products are available at http //www.semichem.com/prods.html. AMPAC , available as a stand-alone product with Windows-based and work-station-level interfaces, is a semiempirical quantum mechanical program featuring SAMI, AMI, MNDO, MNDO/d, PM3, MNDO/C, and MINDO/3 semiempirical... 

Luzhkov, V. and Warshel, A. Microscopic models for quantum mechanical calculations of chemical processes in solutions LD/AMPAC and SCAAS/AMPAC calculations of solvation energies, J.Comp.Chem 13 (1992), 199-213... 

Fig. 2 Chemical structures of fluorescent ligands (anion coordination sites are indicated in blue) and tentative reaction schemes on interaction of 6 with chloride and fluoride in dichloromethane according to the color patterns observed in [41]. The wavelengths of absorption given in brackets have been calculated for the geometry optimized species 6, 6-C1 and 6 in the gas phase by semiempirical AMI calculations (Ampac V6.55, Semichem)...

The current status of the semiempirical methods pioneered by Michael J. S. Dewar is given. These methods are made available to non—theoreticians through the programs MOP AC and AMPAC. Some capabilities of MOPAC and the form of the data input to the program are outlined. 

North America USA (Albany Molecular Research, AMPAC Fine Chemicals, Codexis, Dixie Chemical Group, Dowpharma CMS, Honeywell Life Science Chemicals, SAFC, Synthetech), Canada (Delmar). 

Schematic provided and reproduced with the permission of Oiivier Dapremont (Ampac Fine Chemicais LLC)...

Aerojet (fine chemicals division now acquired by AMPAC) also has reported technology to prepare and use diazomethane on large scale from the reaction of NaOH with N-methyl-N-nitrosamine. This process differs for the Phoenix process in that relatively large amounts of a low-boiling volatile solvent, diethyl ether, are uhlized to limit bulk liquid temperatures and minimize headspace concentrations of diazomethane [22]. 

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