Zimmermann Dathe type Williamson etherification, which can be carried out by a mild base in DMSO, is very useful in preparing ethers.
In this paper, the hydrothermal conversion of glucose to lactic acid (LA) using sodium silicate (Na2SiO3) as a mild base catalyst was investigated.
The best results have been obtained starting from a mild base pressure (1×10−5 Torr) probably due to the presence of water and oxidative atmosphere in the evaporation chamber.
Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility.
Intermediate II converts to III after tautomerization (nanocrystalline MgO can also act as a mild base for the deprotonation of an acidic proton of Intermediate II).
But when ground up and subjected to a mild base at 100°C, the lignins readily fall apart, releasing twice as many sugars as their wild-type kin do under the same conditions.
The use of a mild base, e.g., sodium bicarbonate, is essential, because stronger bases, e.g., NaOH, cause pyruvate to polymerize (Supporting Information (SI), Figure S7).
When substituted benzyl bromide or allyl bromide was used (2b 4b, 6b), a mild base (anhydrous K2CO3) was potent enough to drive the reaction to completion.
In view of the success of rhodium catalysis in related transformations,[ 2d– g, i, k– q] the reaction of 1 a with PhB(OH 2 in the presence of [{Rh(cod Cl}2] (1.5 mol %), KF (1.5 equiv) as a mild base, and tBuOH (1.5 equiv) as a proton source was examined [Eq. (1)].
To avoid tedious separation of the co-migrating products, the mixture was subjected to regioselective 6- O-protection with allyloxycarbonyl group by the action of AllocCl in the presence of a mild base sym-collidine, which transformed compound 13 into 6- O-Alloc-protected 15, whereas the 4-OH derivative 14 was unaffected.
An example is the OH- or hydroxide ion which is a mild base.
