Special Issue "Reactions in Water"

Guest Editor
em. Prof. Dr. Jan B.F.N. Engberts
Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
E-Mail: j.b.f.n.engberts@gmail.com
Interests: chemistry in water; hydrophobic interactions; catalysis in water; chemistry of amphiphiles; gene delivery by vesicles

Dear Colleagues,

Whereas the single water molecular has no perculiar properties apart from being very small, it is the aqueous liquid, with its highly dynamic three-dimensional hydrogen-bond network, that has many unique properties. All living systems are critically dependent on the presence of water, both as a medium and as a reagent. In physical-organc chemistry it is often the medium of choice, in part because of its high dielectric constant that avoids ion pair formation and the associated kinetic complexities. Although being the ultimate green solvent, in synthetic chemistry water has for a long time not been popular for two main reasons: (1) the limited solubility of  many apolar substrates and (2) the instability of  a variety of functional groups in aqueous media.

In the past three decades there have been many new developments. Kinetic studies, performed at low substrate concentrations, showed that hydrophobic effects had highly interesting effects both on the reactivity of apolar substrates in water as well as on the stereochemistry of these reactions. Particularly pericyclic reactions have been examined in considerable detail. A second breakthrough came from the group of Sharpless. In contrast with traditional beliefs, it was found that the limited solubilities of organic substrates can be turned into an advantage. A number of transformations, conducted in heterogeneous aqueous suspensions, showed high yields, often improved reaction rates and favorable stereochemistry. Such “on-water reactions” opened many novel possibilities for powerful synthetic protocols in water and for mechanistic investigations.

“Reactions in Water” remains a highly challenging topic for further investigation of the secrets that the aqueous medium has to offer to present day scientists in the area. I kindly invite my colleagues to submit their novel results to the Special Issue of Molecules. We are eagerly awaiting your contributions!

Dr. Jan B.F.N. Engberts
Guest Editor

Submission

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• organic, inorganic and  organometallic reactions in water
• mechanism of reactions in water
• hydrophobic effects on organic reactivity
• water, the ultimate green solvent for chemical transformations
• (bio)catalytic processes in water
• (stereo)selective reactions in water
• reactions in highly aqueous mixed solvents
• “On-water reactions”, mechanism and synthetic applications
• molecular recognition chemistry in water
• systems chemistry in water
• aqueous reactivity of apolar substrates undergoing self-coiling
• catalysis by surfactant aggregates and cyclodextrines in water
• microwave-assisted aqueous reactions
• reactions in supercritical water

Type of Paper: Article
Title: Linear Polystyrene-Stabilized PdO Nanoparticles Catalyzed Mizoroki-Heck Reaction in Water
Authors: Atsushi Ohtaka, Tomohiro Yamaguchi, Takuto Teratani, Osamu Shimomura, and Ryoki Nomura
Affiliation: Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology, Japan; E-Mail:otaka@chem.oit.ac.jp
Abstract: The Mizoroki-Heck reaction of iodobenzene with acrylic acid in the presence of linear polystyrene-stabilized PdO nanoparticles in KOH aqueous solution at 90 °C for 5 h gave cinnamic acid quantitatively. The catalyst was reused ten times without significant loss of activity

Type of Paper: Article
Title: The Role of Water in Lanthanide-Catalyzed Carbon-Carbon Bond Formation
Authors: Derek J. Averill, Prabani Dissanayake, Hanan Yahya, and Matthew J. Allen
Affiliations: Department of Chemistry, Wayne State University, 5101 Cass Avenue Detroit, MI  48202, USA; E-Mail: mallen@chem.wayne.edu
Abstract: The formation of carbon-carbon bonds in aqueous media has environmental and cost benefits because it eliminates the need to rigorously dry organic solvents. Our newly developed tool of luminescence-decay measurements to study catalysis in aqueous systems was used to perform a mechanistic study of the relationships between rates of catalysis and water-coordination numbers of a series of lanthanide-based catalysts. A correlation between reaction rate and water-coordination number was observed and is reported here.

Type of Paper: Article
Title: Eco-friendly Electrophilic Lodination of Aromatic and Heteroaromatic Compounds Promoted by Iodine and Hydrogen Peroxide Using Water as Solvent
Author: Cristiano Raminelli
Affiliation: Faculdade de Ciências Exatas e Tecnologia, Universidade Federal da Grande Dourados, Rodovia Dourados-Itahum, Km 12, Cidade Universitária, Dourados, MS, Brazil; Email: raminelli@ufgd.edu.br
Abstract: The reaction of aromatic and heteroaromatic compounds with iodine in the presence of hydrogen peroxide using water as solvent has produced useful iodinated molecules in high yields.

Type of Paper: Article
Title: Study of the Reaction 2-(nitrophenyl)ethyl Bromide⁺ OH^- in Dimeric Micellar Solutions
Authors: María del Mar Graciani, Amalia Rodríguez, Victoria Isabelm Martín and María Luisa Moyá
Affiliation: Department of Physical Chemistry, University of Seville, C/Profesor garcía González 1 41012, Seville, Spain; E-Mail: moya@us.es
Abstract: The dehydrobromination reaction 2-(p-nitrophenyl)ethyl bromide⁺ OH^- was investigated in several alkanediyl-α-ω-bis(dodecyldimethylammonium) bromide, 12-s-12,2Br- (with s=2, 3, 4, 5, 6, 8, 10, 12) micellar solutions, in the presence of NaOH 5x10^-3 M. The kinetic data were quantitatively rationalized within the whole surfactant concentration range by using an equation based on the pseudophase ion-exchange model and taking the variations in the micellar ionization degree caused by the morphological transitions into account. The agreement between the theoretical and the experimental data was good in all the dimeric micellar media studied, except for the 12-2-12,2Br- micellar solutions. In this case, the strong tendency to micellar growth shown by the 12-2-12,2Br- micelles could be responsible for the lack of accordance. Results showed that the dimeric micelles accelerate the process more than two orders of magnitude as compared to water.