The Use of Nickel as a Catalyst for Hydrogenation. Ii

Abstract

A study of the preparation of nickel catalysts1 indicated that in general sodium bicarbonate was to be preferred to sodium carbonate or potassium hydroxide as a precipitant in the preparation of nickel catalysts. This was true because the resulting catalysts were somewhat more active and less sensitive to variations in the procedure of preparation. More recently it has become evident that ammonium carbonate is in general the most satisfactory precipitant.Procedure Recommended for the Preparation of a Nickel Catalyst.-Fifty-eight grams of Baker and Adamson or Mallinckrodt c. p. nickel nitrate hexahydrate (Ni(N03)2-6H20), dissolved in 80 ml. of distilled water, was ground for thirty to sixty minutes in a mortar with 50 g. of acid washed kieselguhr (ex Johns-Manville "Filter-Cel") until the mixture was ap-726 mm.).h This fraction was taken 76 to 80°( 11 mm.). The diethyl acetal of tetrahydrofurfural was reported by Scheibler, Sotscheck and Friese [Ber., 57, 1443 (1924)] to have a boiling range of 187-190°. Bolander and Minne in this Laboratory have found the boiling point of the pure compound to be 194.5°. hydrogenation of a variety of organic compounds as summarized in the paragraphs in "Other Hydrogenations'' and in Table IV.

Synthesis of 6-Formyl Derivatives of 5,8-Dimethoxycarbostyryl

“…An attempt to oxidize 7 by the method described above failed, since the first step afforded compound (9) through bromination at the more reactive C4-Me group followed by allylic rearrangement under the purification conditions. A literature search revealed the existence of an early precedent of the hydrogenolysis of cyclic acetals derived from aromatic carbonyl compound^.^^ The change of the protective moup to a 1,3-dithiane derivative (compound (13)) allowed the preparation of amine (14) by reduction with stannous chloride in hydrochloric acid. We initiated the synthesis of potential starting materials by attempting to reduce 4-nitro-25-dimethoxybenzaldehyde (10) 11 to the corresponding m i n e (11).…”

“….5'-Dimethoxv-4-methvlnhenvl~acetoacetde (6). Found: C, 47.76; H, 4.92: N, 4.72.2.5-Dimethoxv-4-(1'.3'dithian-2'-vl~anilin~(14).A suspension of 13 (1 g, 0.33 mmol) and stannous chloride dihydrate (4.32 g, 27.5 mmol of SnC12) in 35 % hydrochloric acid (13 ml) was stirred at room temperature for 24 h. The reaction was basified with 20 % sodium hydroxide and extracted with chloroform (4 x 25 ml). 2,2,6-Trimethyl-l,3-dioxin-4-one (730 mg, 5.14 mmol) was added dropwise.…”

Reduction of Acetals, Azaacetals and Thioacetals to Ethers

“…44 ,45 Propargylic acetals undergo reductive cleavage via an elimination mechanism during hydroboration (Scheme 3; (f Scheme 2). ( 12) Sodium borohydride and trifluoroacetic acid (TFA) reduce 2-aryl-l,3-dioxolanes to hydroxy ethers. 49 The diethyl acetal of benzaldehyde can be reduced to ethyl benzyl ether in moderate yield by decaborane in toluene at 120-130°c (equation 12).…”

Highly Chemoselective Copper-Catalyzed Conjugate Reduction of Stereochemically Labile α,β-Unsaturated Amino Ketones

“…Chemoselective reduction of variously conjugated and isolated C-C double bonds presents a significant challenge in organic chemistry even with the plethora of available methods since the report by Adkins on the use of nickel catalysts for reduction of mesityl oxide to methyl isobutyl ketone, among other substrates. 1 Several reagents are known for achiral conjugate reduction of unsaturated carbonyl compounds such as triethylsilane, using catalytic (Ph 3 P) 3 RhCl, 2 K-selectride, 3 hydrogen gas, 4 and trialkylammonium formates 5 in the presence of Pd/C, sodium dithionite, 6 Raney nickel, 7 and various silanes in the presence of catalytic amounts of rhodium(bisoxazolinylphenyl) complexes. 8 Stoichiometric [CuH(PPh 3 )] 6 (Stryker's reagent) 9 and catalytic [CuH(PPh 3 )] 6 in the presence of hydrogen gas 10 or silanes 11 can also be used for 1,4-reduction.…”