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pKa values for acetic, chloroacetic, dichloroacetic and trichloroacetic acids. Inductive effects and mesomeric effects affect the pK a values. A simple example is provided by the effect of replacing the hydrogen atoms in acetic acid by the more electronegative chlorine atom.
As a reagent in organic chemistry, DBU is used as a ligand and base. As a base, protonation occurs at the imine nitrogen. [5] Lewis acids also attach to the same nitrogen. [6] These properties recommend DBU for use as a catalyst, for example as a curing agent for epoxy resins and polyurethane.
Since Tris' pKa is more strongly temperature dependent, its use is not recommended in biochemical applications requiring consistent pH over a range of temperatures. Moreover, the temperature dependance of the pKa (and in turn buffer solution pH) makes pH adjustment difficult. [8] (E.g., the 'room temperature' pH adjustment would not translate ...
The reducing power of DTT is limited to pH values above 7, since only the negatively charged thiolate form -S − is reactive (the protonated thiol form -SH is not); the pKa of the thiol groups is 9.2 and 10.1. Reduction of a typical disulfide bond by DTT via two sequential thiol-disulfide exchange reactions.
DABCO (1,4-diazabicyclo[2.2.2]octane), also known as triethylenediamine or TEDA, is a bicyclic organic compound with the formula N 2 (C 2 H 4) 3.This colorless solid is a highly nucleophilic tertiary amine base, which is used as a catalyst and reagent in polymerization and organic synthesis.
TFA is also less oxidizing than sulfuric acid but more readily available in anhydrous form than many other acids. One complication to its use is that TFA forms an azeotrope with water (b. p. 105 °C). TFA is used as a strong acid to remove protecting groups such as Boc used in organic chemistry and peptide synthesis. [8] [9]
N,N′-Dicyclohexylcarbodiimide (DCC or DCCD) [1] is an organic compound with the chemical formula (C 6 H 11 N) 2 C. It is a waxy white solid with a sweet odor. Its primary use is to couple amino acids during artificial peptide synthesis.
In organic synthesis, PPTS is used as a weakly acidic catalyst, providing an organic soluble source of pyridinium (C 5 H 5 NH +) ions.For example, PPTS is used to deprotect silyl ethers or tetrahydropyranyl ethers when a substrate is unstable to stronger acid catalysts.