Aluminum isopropylate

Aluminum complex greases, obtained by the reaction of aluminum isopropylate with a mixture of benzoic acid and fatty acids. These greases have a remarkable resistance to water, very good adhesion to metallic surfaces, good mechanical stability properties and resistance to temperature. They are less common than the first two types. 

The first question can be answered relatively simply (although not completely exactly) from the available factual material. If the pK value of the lactam is taken as a criterion, the border of reactivity lies at about pK 12. Valerolactam and caprolactam react just noticeably with diazomethane (yields 14 and 7%). However, it should be noticed that catalysts are frequently necessary in order to initiate the reaction (methanol, water, aluminum isopropylate," fluoboric acid " ). For example, phthalimide does not react at all with diazomethane in ether, but a smooth reaction occurs if some methanol is added. 

By oxidation in 100 cc of absolute toluol with 425 cc of cyclohexanone and 155 cc of a 20% aluminum isopropylate solution in absolute toluol and after repeated crystallizations from isopropyl ether or methanol, 24 grams of pure 17o-oxyprogesterone-17-caproate is obtained, MP 119° to 121°C (dense needles). 

Oxidizing this product with aluminum, isopropylate in the presence of cyclohexanone gives desoxycorticosterone acetate (27.2.6) [35,36]. 

The use of aluminum isopropylate as a catalyst for this alkylation is apparently advantageous (128, 180). The resulting 18-ethers are formulated as 18-/3-alkoxy compounds, since it has been demonstrated in the steroid series that this alkylation proceeds with retention of the configuration (181). 

Liquid phase modifications. Alternatively a porous membrane can be reduced in pore size by a liquid deposition prcx ess where the membrane is dipped into a solution or sol to form deposits inside the membrane pores. For example, a silicon nitride tube with a mean pore diameter of 0.35 pm is first immersed in a solution of aluminum alcoholate (aluminum isopropylate or 2aluminum tris(ethyl acetoacetate) or ethyl acetoacetate aluminum diisopropylate) in an organic solvent (hexane, cyclohexane, benzene, isopropanol, etc.). It is then treated with saturated water vapor to hydrolyze the alcoholate or chelate to form bochmite inside the pores, thus changing the pore diameter to as small as 20 nm [Mitsubishi Heavy Ind., 1984a and 1934b]. Upon calcining at 800X, boehmite transforms into transition-alumina. 

Lund, H. Aluminum isopropylate as a reducing agent. A general method for carbonyl reduction. Ber. 1937, 70B, 1520-1525. 

Derivation By reduction of tribromoacetaldehyde with aluminum isopropylate. 

Whitaker, G. C., Aluminum alcoholates and the commercial preparation and uses of aluminum isopropylate, in Metal Organic Compounds. Advances in Chemistry Series. No. 23, pp. 184-189, Sept. 1959. 

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