Search results
Results from the WOW.Com Content Network
The k' pathway implicates a reaction between the doubly charged anion (RCHO 2 2−) and the aldehyde. The direct transfer of hydride ion is evident from the observation that the recovered alcohol does not contain any deuterium attached to the α-carbon when the reaction is performed in the presence of D 2 O.
The alkylphosphonium salt is deprotonated with a strong base such as n-butyllithium: [Ph 3 P + CH 2 R]X − + C 4 H 9 Li → Ph 3 P=CHR + LiX + C 4 H 10. Besides n-butyllithium (n BuLi), other strong bases like sodium and potassium t-butoxide (t BuONa, t BuOK), lithium, sodium and potassium hexamethyldisilazide (LiHMDS, NaHMDS, KHDMS, where HDMS = N(SiMe 3) 2), or sodium hydride (NaH) are also ...
Sodium hydride is the chemical compound with the empirical formula Na H. This alkali metal hydride is primarily used as a strong yet combustible base in organic synthesis . NaH is a saline (salt-like) hydride , composed of Na + and H − ions, in contrast to molecular hydrides such as borane , silane , germane , ammonia , and methane .
Fig. 1 shows an example of a diastereoselective CBS reduction being used to prepare a complex macrocyclic alcohol en route to the synthesis of 11-desmethyllaulimalide [22] (an analog of the antitumor agent laulimalide). The authors noted that CBS reduction was much more effective than using either lithium tert-butoxyaluminum hydride or L ...
Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids. [1] A variety of oxidants can be used.
To selectively form the allyl alcohol and avoid the 1,4 product, the Luche reduction uses "cerium borohydride" generated in situ from NaBH 4 and CeCl 3 (H 2 O) 7 [21] [22] The hydride source Zn(BH 4) 2 also shows 1,2 selectivity, as well as greater diastereoselectivity.
Trimethyl borate is the main precursor to sodium borohydride by its reaction with sodium hydride in the Brown-Schlesinger process: 4 NaH + B(OCH 3) 3 → NaBH 4 + 3 NaOCH 3. It is a gaseous anti-oxidant in brazing and solder flux. Otherwise, trimethyl borate has no announced commercial applications.
In practice, considerable sodium is consumed by the formation of hydrogen. [citation needed] For this reason, an excess of sodium is often required. Because the hydrolysis of sodium is rapid, not to mention dangerous, the Bouveault-Blanc reaction requires anhydrous ethanol and can give low yields with insufficiently dry ethanol.