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4-Iodobenzoic Acid
4-Iodobenzoic acid, or ''p''-iodobenzoic acid, is an isomer of iodobenzoic acid. Structure X-ray crystallography of 4-iodobenzoic acid has shown that it crystallizes in the solid state as hydrogen-bonded dimers which stack perpendicular to their aromatic rings. The iodine atoms of adjacent dimers are also oriented towards each other due to van der Waals forces. Preparation 4-Iodobenzoic acid may be prepared in the laboratory by the oxidation of ''p''-iodotoluene with potassium permanganate. Reactions The carboxylic acid functionality of 4-iodobenzoic acid undergoes Fischer–Speier esterification Fischer esterification or Fischer–Speier esterification is a special type of esterification by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. The reaction was first described by Emil Fischer and Arthur Speier in ... with methanol to form the ester methyl 4-iodobenzoate. References {{DEFAULTSORT:Iodobenzoic acid, 4- Benzoic acids 4-Iodophen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma Aldrich
Sigma-Aldrich (formally MilliporeSigma) is an American chemical, life science, and biotechnology company that is owned by the German chemical conglomerate Merck Group. Sigma-Aldrich was created in 1975 by the merger of Sigma Chemical Company and Aldrich Chemical Company. It grew through various acquisitions until it had over 9,600 employees and was listed on the Fortune 1000. The company is headquartered in St. Louis and has operations in approximately 40 countries. In 2015, the German chemical conglomerate Merck Group acquired Sigma-Aldrich for $17 billion. The company is currently a part of Merck's life science business and in combination with Merck's earlier acquired Millipore, operates as MilliporeSigma. History Sigma Chemical Company of St. Louis and Aldrich Chemical Company of Milwaukee were both American specialty chemical companies when they merged in August 1975. The company grew throughout the 1980s and 1990s, with significant expansion in facilities, acquisitio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodobenzoic Acid
Iodobenzoic acids are any of three organic compounds with the formula IC6H4COOH, consisting of a carboxylic acid group and an iodine atom bonded to a central benzene ring. They can be considered as aryl iodide, iodinated derivatives of benzoic acid, or as carboxylic acid, carboxylated variants of iodobenzene. References {{reflist Iodobenzene derivatives Benzoic acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PubChem
PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information (NCBI), a component of the National Library of Medicine, which is part of the United States National Institutes of Health (NIH). PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be freely downloaded via FTP. PubChem contains multiple substance descriptions and small molecules with fewer than 100 atoms and 1,000 bonds. More than 80 database vendors contribute to the growing PubChem database. History PubChem was released in 2004 as a component of the Molecular Libraries Program (MLP) of the NIH. As of November 2015, PubChem contains more than 150 million depositor-provided substance descriptions, 60 million unique chemical structures, and 225 million biological activity test results (from over 1 million assay experiments performed on mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimer (chemistry)
A dimer () (''di-'', "two" + ''-mer'', "parts") is an oligomer consisting of two monomers joined by bonds that can be either strong or weak, covalent or intermolecular. Dimers also have significant implications in polymer chemistry, inorganic chemistry, and biochemistry. The term ''homodimer'' is used when the two molecules are identical (e.g. A–A) and ''heterodimer'' when they are not (e.g. A–B). The reverse of dimerization is often called dissociation. When two oppositely charged ions associate into dimers, they are referred to as ''Bjerrum pairs'', after Niels Bjerrum. Noncovalent dimers Anhydrous carboxylic acids form dimers by hydrogen bonding of the acidic hydrogen and the carbonyl oxygen. For example, acetic acid forms a dimer in the gas phase, where the monomer units are held together by hydrogen bonds. Under special conditions, most OH-containing molecules form dimers, e.g. the water dimer. Excimers and exciplexes are excited structures with a short life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stacking (chemistry)
In chemistry, pi stacking (also called π–π stacking) refers to the presumptive attractive, noncovalent pi interactions (orbital overlap) between the pi bonds of aromatic rings. However this is a misleading description of the phenomena since direct stacking of aromatic rings (the "sandwich interaction") is electrostatically repulsive. What is more commonly observed (see figure to the right) is either a staggered stacking (parallel displaced) or pi-teeing (perpendicular T-shaped) interaction both of which are electrostatic attractive For example, the most commonly observed interactions between aromatic rings of amino acid residues in proteins is a staggered stacked followed by a perpendicular orientation. Sandwiched orientations are relatively rare. Pi stacking is repulsive as it places carbon atoms with partial negative charges from one ring on top of other partial negatively charged carbon atoms from the second ring and hydrogen atoms with partial positive charges on top ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Der Waals Forces
In molecular physics, the van der Waals force is a distance-dependent interaction between atoms or molecules. Unlike ionic or covalent bonds, these attractions do not result from a chemical electronic bond; they are comparatively weak and therefore more susceptible to disturbance. The van der Waals force quickly vanishes at longer distances between interacting molecules. Named after Dutch physicist Johannes Diderik van der Waals, the van der Waals force plays a fundamental role in fields as diverse as supramolecular chemistry, structural biology, polymer science, nanotechnology, surface science, and condensed matter physics. It also underlies many properties of organic compounds and molecular solids, including their solubility in polar and non-polar media. If no other force is present, the distance between atoms at which the force becomes repulsive rather than attractive as the atoms approach one another is called the van der Waals contact distance; this phenomenon res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Journal Of Physical Chemistry A
''The Journal of Physical Chemistry A'' is a scientific journal which reports research on the chemistry of molecules - including their dynamics, spectroscopy, kinetics, structure, bonding, and quantum chemistry. It is published weekly by the American Chemical Society. Before 1997 the title was simply ''Journal of Physical Chemistry''. Owing to the ever-growing amount of research in the area, in 1997 the journal was split into ''Journal of Physical Chemistry A'' (molecular theoretical and experimental physical chemistry) and '' The Journal of Physical Chemistry B'' (solid state, soft matter, liquids, etc.). Beginning in 2007, the latter underwent a further split, with '' The Journal of Physical Chemistry C'' now being dedicated to nanotechnology, molecular electronics, and related subjects. Editors-in-chief *1896–1932 Wilder Dwight Bancroft, Joseph E. Trevor *1933–1951 S. C. Lind *1952–1964 William A. Noyes *1965–1969 F. T. Wall *1970–1980 Bryce Crawford *1980–200 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-Iodotoluene
Iodotoluenes are aryl iodides based on toluene in which at least one aromatic hydrogen atom is replaced with an iodine atom. They have the general formula C7H8–''n''I''n'', where ''n'' = 1–5 is the number of iodine atoms. Monoiodotoluene Monoiodotoluenes are iodotoluenes containing one iodine atom. There are three isomers, each with the formula C7H7I. Properties The isomers differ in the location of the iodine, but have the same chemical formula. Benzyl iodide is an isomer, which has a iodine substituted for one of the hydrogens of toluene's methyl group, and it is sometimes named α-bromoiodine. Preparation A laboratory route to ''o''- and ''p''-iodotoluene proceeds from toluene, which is treated with a mixture of iodine and nitric acid in an electrophilic aromatic substitution. The resulting mixture of ''o'' and ''p''-iodotoluene is then separated by fractional freezing; cooling the mixture in an ice bath results in solidification of ''p''-iodotoluene, which can then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Permanganate
Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and , an intensely pink to purple solution. Potassium permanganate is widely used in the chemical industry and laboratories as a strong oxidizing agent, and also as a medication for dermatitis, for cleaning wounds, and general disinfection. It is on the World Health Organization's List of Essential Medicines. In 2000, worldwide production was estimated at 30,000 tonnes. Properties Potassium permanganate is the potassium salt of the tetrahedral transition metal oxo complex permanganate, in which four O2- ligands are bound to a manganese(VII) center. Structure KMnO4 forms orthorhombic crystals with constants: ''a'' = 910.5 pm, ''b'' = 572.0 pm, ''c'' = 742.5 pm. The overall motif is similar to that for barium sulfate, with which it forms solid solutions. In the solid (as in solution), each MnO4− c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fischer–Speier Esterification
Fischer esterification or Fischer–Speier esterification is a special type of esterification by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. The reaction was first described by Emil Fischer and Arthur Speier in 1895. Most carboxylic acids are suitable for the reaction, but the alcohol should generally be primary or secondary. Tertiary alcohols are prone to elimination. Contrary to common misconception found in organic chemistry textbooks, phenols can also be esterified to give good to near quantitative yield of products. Commonly used catalysts for a Fischer esterification include sulfuric acid, p-toluenesulfonic acid, and Lewis acids such as scandium(III) triflate. For more valuable or sensitive substrates (for example, biomaterials) other, milder procedures such as Steglich esterification are used. The reaction is often carried out without a solvent (particularly when a large reagent excess of alcohol is used) or in a non-polar solvent (e.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
