Search results
Results from the WOW.Com Content Network
Reaction Sequences: Multistep synthesis involves sequential chemical reactions, each requiring its own work-up to isolate intermediates before proceeding to the next stage. [ 4 ] For example, the synthesis of paracetamol typically requires three separate reactions.
Using the twenty natural amino acids, for example, in a tripeptide creates 8,000 (20 3) possibilities. Solid-phase methods for small molecules were later introduced and Furka devised a "split and mix" approach [2] [4] In its modern form, combinatorial chemistry has probably had its biggest impact in the pharmaceutical industry. [5]
One example of a synthesis reaction is the combination of iron and sulfur to form iron(II) sulfide: + Another example is simple hydrogen gas combined with simple oxygen gas to produce a more complex substance, such as water.
Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature". [6]
The Ugi reaction has been applied in combination with an intramolecular Diels-Alder reaction [16] in an extended multistep reaction. A reaction in its own right is the Ugi–Smiles reaction with the carboxylic acid component replaced by a phenol. In this reaction the Mumm rearrangement in the final step is replaced by the Smiles rearrangement. [17]
Combination of two active chain ends: one or both of the following processes may occur. Combination: two chain ends simply couple together to form one long chain (Figure 14). One can determine if this mode of termination is occurring by monitoring the molecular weight of the propagating species: combination will result in doubling of molecular ...
For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H 2 O. In the case of non-stoichiometric compounds , the proportions may be reproducible with regard to their preparation, and give fixed proportions of their component elements, but proportions that are not integral [e.g., for palladium ...
These reactions are more likely to involve a series of bimolecular reactions. New MCR's are found by building a chemical library from combinatorial chemistry or by combining existing MCR's. [3] For example, a 7-component MCR results from combining the Ugi reaction with the Asinger reaction. [4] MCR's are an important tool in new drug discovery.