The recent advances in nanotechnology and the corresponding increase in the use of nanomaterials in products in every sector of society have resulted in uncertainties regarding environmental impacts. The objectives of this review are to introduce the key aspects pertaining to nanomaterials in the environment and to discuss what is known concerning their fate, behavior, disposition, and toxicity, with a particular focus on those that make up manufactured nanomaterials. This review critiques existing nanomaterial research in freshwater, marine, and soil environments. It illustrates the paucity of existing research and demonstrates the need for additional research. Environmental scientists are encouraged to base this research on existing studies on colloidal behavior and toxicology. The need for standard reference and testing materials as well as methodology for suspension preparation and testing is also discussed.

Nanomaterials in the environment: Behavior, fate, bioavailability, and effects

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

Asymmetric 1,3-Dipolar Cycloaddition Reactions

One of the initial steps in the development of therapeutic agents is the identification of lead compounds that bind to the receptor or enzyme target of interest. Many analogs of these lead compounds are then synthesized to define the key recognition elements for maximal activity. In general, many compounds must be evaluated in both the lead identification and optimization steps. Increasing burdens have been placed on these efforts due to the large number of new therapeutic targets that continue to be identified thorough modern molecular biology methods.1 To address this demand, very powerful chemical and biological methods have been developed for the generation of large combinatorial libraries of peptides2 and oligonucleotides3 that are then screened against a receptor or enzyme to identify high-affinity ligands or potent inhibitors, respectively. While these studies have clearly demonstrated the power of library synthesis and screening strategies, peptides and oligonucleotides generally have poor oral activities and rapid in vivo clearance;4 therefore their utility as bioavailable therapeutic agents is often limited. Due to the favorable pharmacokinetic properties of many small organic molecules (<600-700 molecular weight),5 the design, synthesis, and evaluation of libraries of these compounds6 has rapidly become a major frontier in organic chemistry. Lorin A. Thompson was born in Lexington, KY, in 1970. He received the Bachelor of Science degree from the University of North Carolina, Chapel Hill, in 1992 where he worked under the guidance of Joseph Desimone. He is currently pursuing his doctorate in the laboratory of Jonathan Ellman at UC Berkeley where he is the 1994 Glaxo-Wellcome fellow. His research interests include the development of synthetic methodology for organic library construction.

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Synthesis and Applications of Small Molecule Libraries.

1,2-Amino Alcohols and Their Heterocyclic Derivatives as Chiral Auxiliaries in Asymmetric Synthesis

Pyridinium methylides bearing an anion-stabilizing substituent at the ylide carbon react with a variety of olefins carrying two electron-withdrawing groups at the both carbons such as N-substituted maleimides, a citraconimide, dimethyl maleate, dimethyl fumarate, and 1,2-dibenzoylethene. The cycloadducts thus formed undergo a ready elimination of pyridines when treated with silica gel. This sequence is a new method for alkylation or hydroalkylidenation of olefins.

Cycloaddition of Pyridinium Methylides with Electron-Deficient Olefins and Silica-Gel Mediated Elimination of Pyridines from the Cycloadducts: A New Method of Alkylation or Hydroalkylidenation of Olefins.

Studies on the selective preparation of aromatic compounds. part x. the preparation of alkyl phenols using tert-butyl function as a positional protective group

Tetraaminoaethylene 1. mitt. darst. und rk. von tetrapiperidino- und tetramorpholino-aethylen

1-Alkenyl cyclopropyl ketones, when activated by cation-stabilizing substituents at the ring carbon or at the terminal carbon of the enone moiety, undergo polyphosphoric acid-catalyzed ring enlargement producing cyclopentanone or cyclohexenone derivatives. Similar acid-catalyzed ring opening of 1-alkenyl 2-phenoxycyclopropyl ketones offers a convenient and effective synthesis of 4-oxo-5-alkenals and their dioxolaneprotected derivatives.

Synthesis and Acid‐Catalyzed Ring Opening of 1‐Alkenyl Cyclopropyl Ketones.

A method for handling and stabilizing a (2-alkyl)acryloyl isocyanate represented by formula (1) is disclosed, which comprises the steps of: 
   reacting an azomethine compound represented by formula (2) with the (2-alkyl)acryloyl isocyanate to obtain a reaction product and 
   dissolving the reaction product into a solvent to regenerate the (2-alkyl)acryloyl isocyanate;
 wherein R¹ represents a hydrogen atom or a lower alkyl group,
 wherein 
R² represents an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, or an alkynyl group, and 
R³ and R⁴ each represents a hydrogen atom or a group which does not cause tautomerism with C=N in the formula, provided that at least one of R³ and R⁴ is not a hydrogen atom, and further a method for producing a (2-alkyl)acryloyl isocyanate is disclosed, which comprises the step of: 
   preparing a heterocyclic compound represented by formula (3) and 
   dissolving the heterocyclic compound into a solvent;
 wherein R¹ represents a hydrogen atom or a lower alkyl group,
 wherein 
R⁵ represents a hydrogen atom or a lower alkyl group, 
R⁶ represents an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, or an alkynyl group, and 
R⁷ and R⁸ each represents a hydrogen atom or a group in which a carbon atom located in the α-position to carbon atoms constituting a heterocyclic ring does not have a hydrogen atom, provided that at least one of R⁷ and R⁸ is not a hydrogen atom.

Method for handling (2-alkyl) acryloyl isocyanate, method for producing (2-alkyl)acryloyl isocyanate, heterocyclic compound, and method for producing heterocyclic compound

Otohiko Tsuge

Papers

Cycloaddition of Pyridinium Methylides with Electron-Deficient Olefins and Silica-Gel Mediated Elimination of Pyridines from the Cycloadducts: A New Method of Alkylation or Hydroalkylidenation of Olefins.

Studies on the selective preparation of aromatic compounds. part x. the preparation of alkyl phenols using tert-butyl function as a positional protective group

Tetraaminoaethylene 1. mitt. darst. und rk. von tetrapiperidino- und tetramorpholino-aethylen

Synthesis and Acid‐Catalyzed Ring Opening of 1‐Alkenyl Cyclopropyl Ketones.

Method for handling (2-alkyl) acryloyl isocyanate, method for producing (2-alkyl)acryloyl isocyanate, heterocyclic compound, and method for producing heterocyclic compound