In December 2017 the United Nations proclaimed that 2019 will be international year of the Periodic Table of the Chemical Elements. This coincides with the 150th anniversary of the periodic system discovered by Dmitry Mendeleev in 1869. We at Scientific Update love a good celebration so over the coming months, and in honour of this
Category: Topical tips
The generation of lithium-alkoxide based aryl and heteroaryl Grignard reagents by Mg-Br/Cl exchange in toluene- increased reactivity and wide applicability. Organomagnesium-based organometallics are used extensively in organic chemistry. Historically the reagents were prepared by direct insertion of magnesium metal into organic halides. With demand for more industrially applicable methods, halogen-magnesium exchange using alkyl magnesium halides
A patent issued this month cites the use of catalytic tetrabutylammonium bromide (TBAB) in the ring opening esterification of glycidyl ethers using acrylic acid and methacrylic acid (see Example 7). In PTC esterifications, we typically expect the presence of a base to form the carboxylate salt from the acid then the quat acrylate would
A patent just issued last month to Sachem, one of the most veteran manufacturers of high purity quaternary ammonium phase-transfer catalysts, that describes how to inhibit color formation of quat hydroxides in non-aqueous solvents (glycols). Sachem has been a leader in the commercial supply of quat hydroxides, especially those used in the manufacture of semiconductors.
Phase-transfer catalyst or PTC is a catalyst that facilitates the migration of a reactant from one phase into another phase where reaction occurs. Phase-transfer catalysis is a special form of heterogeneous catalysis. Ionic reactants are often soluble in an aqueous phase but insoluble in an organic phase in the absence of the phase-transfer catalyst. The catalyst functions like a detergent for solubilizing
If you had suggested 10 years ago that it would be a good idea to try and develop some of the reactions that you can now carry out using photoredox catalysis, you would probably have been labelled as deluded, if you were not locked away for your own safety. But photoredox catalysis has come a
ICH M7 provides greater flexibility to assess the risk posed by Mutagenic Impurities. This is described in section 8 – Control of the guideline and defined as a series of control options. Of these Option 4 permits an applicant to present an argument for control based on the physico-chemical properties of a mutagen and the
The halex reaction is a great way to introduce a fluorine atom in to an aromatic ring, but the reaction often requires high temperatures and or long reaction times if metal fluorides are used. Tetralkylammonium fluorides are a better option due to their higher solubility in the reaction medium, however these salts are often hydrated
Considering the environmental footprint of a typical pharmaceutical / agrochemical process, 60-80% arises from the use of solvents. Good solvent selection and use – can be the biggest positive hit on improving the sustainability of a process. The timely identification of an optimum chemical route can save you time and money. An efficient route, selected
Permissible limits for impurities during clinical development has always been a grey area. Existing guidelines, specifically ICH Q3A only formally apply to marketed products. How factors such as duration of clinical trials have never been effectively addressed.