Sodium Hydride-Palladium(II) Acetate-Sodium t-Pentoxide

NaH + Pd(OAc)2 + NaO-t-C5H11

[7646-69-7]  · HNa  · Sodium Hydride-Palladium(II) Acetate-Sodium t-Pentoxide  · (MW 24.00) (Pd(OAc)2)

[3375-31-3]  · C4H6O4Pd  · Sodium Hydride-Palladium(II) Acetate-Sodium t-Pentoxide  · (MW 224.52) (NaO-t-C5H11)

[14593-46-5]  · C5H11NaO  · Sodium Hydride-Palladium(II) Acetate-Sodium t-Pentoxide  · (MW 110.15)

(complex reducing agent; reduction of aromatic halides;1 self-terminating semihydrogenation of alkynes2)

Physical Data: see Sodium Hydride and Palladium(II) Acetate; the t-pentoxide salt is prepared in situ.

Solubility: sol THF, DME, ethanol, hydrocarbon solvents.

Preparative Methods: from NaH, t-pentanol, and Pd(OAc)2 in THF. Add the t-pentanol at 40 °C, as it is very important not to exceed 45 °C throughout the process. After 3 h of stirring at 45 °C, the catalyst is ready for use.1,3,4

Handling, Storage, and Precautions: store under argon in air-tight bottles; moisture sensitive; use in a fume hood.

Reduction of Aromatic Halides.

The reagent can be an effective reducing agent for converting aromatic halides to the corresponding hydrocarbons, as illustrated by the bromonaphthalenes (eq 1).1 Both THF and DME can be used as solvent with a reaction temperature of 63 °C. With THF, the reaction time is 5 min (90-95% yield); with DME, the reaction time increases to 30 min (85-90% yield).

Self-Terminating Semihydrogenation of Alkynes.

This palladium complex reducing agent (Pd CRA) allows semihydrogenation of alkynes to cis-alkenes at atmospheric pressure. For the semihydrogenation of monosubstituted alkynes, reactions must be conducted in solvents such as hexane or octane, whereas the semihydrogenation of disubstituted alkynes are conducted in ethanol, ethanol/hydrocarbon mixtures, or ethanol/THF mixtures. Moreover, in all cases, the presence of Quinoline as a catalyst modifier was necessary (eq 2).2

Related Reagents.

Nickel Complex Reducing Agents; Sodium Hydride; Sodium Hydride-Copper(II) Acetate-Sodium t-Pentoxide; Sodium Hydride-Nickel(II) Acetate-Sodium t-Pentoxide; Zinc Complex Reducing Agents.

1. Brunet, J. J.; Vanderesse, R.; Caubere, P. JOM 1978, 157, 125.
2. Brunet, J.-J.; Caubere, P. JOC 1984, 49, 4058.
3. Brunet, J. J.; Gallois, P.; Caubere, P. TL 1977, 3955.
4. Brunet, J.-J.; Gallois, P.; Caubere, P. JOC 1980, 45, 1937.

Edward J. Parish & Haoyu Qin

Auburn University, AL, USA

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