The Study Of Guerbet Condensation Of Alcohols And Condensations Involving Aldehydes Or Ketones

The reaction that two or more organic molecules combined with covalent bonds while losing simple molecules is called condensation reaction. The carbon chain get longer after condensation reaction. So condensation reactions have important applications in organic synthesis. Researchers focus on new methods or new catalysts of condensation reaction. In this paper, three types of condensation were studied:(1) Guerbet condensation of alcohols under hydroxyapatite (HAP) or metal supported HAP. (2) The condensation of o-phenylenediamine and 1,2-diketone catalyzed by NH4HF2. (3) NH4A1(SO4)2·12H2O catalyzed the condensation of aldehydes and indoles to form diindolylmethane. The paper mainly consists of four parts:The first part:Literature review. Research progress of the three kinds of condensation reactions was listed.The second part:Research of Guerbet condensation of alcohols through vapor-solid catalytic system at atmospheric pressure. We prepared four different Ca/P ratios (0.91,1.07,1.33,1.42) of HAP to catalyze Guerbet condensation. In addition, kinds of metal supported hydroxyapatite catalysts were prepared. Employ these catalysts to investigate Guerbet condensation of ethanol, n-butanol, methanol and n-propanol. Products of the three condensations are n-butanol,2-ethyl-l-hexanol (2EH),2-methyl-l-propanol respectively. Besides, we discussed some factors which have an effect on the reaction, such as temperature, injection speed of reactant, Ca/P ratios of HAP, loading component, amount of loading, different supporters etc. Experiments showed that:(1) The yield of Guerbet alcohols are highest when flowing rate of reactant is 12.5 mL/h. (2) The pure HAP with Ca/P=1.33 was the best catalyst for bimolecular condensation of ethanol and n-butanol, the highest yield of n-butanol and 2EH were 26.10% and 45.8% respectively. The condensation of methanol and H-propanol displayed best results under pure HAP (Ca/P=1.07) at 320℃, the yield of 2-methyl-l-propanol was 90.59%. (3) Ni-MgO supported HAP (Ca/P=1.42) was the best metal supported catalyst. And the optimal loading of Ni was about 4%(3%-5%), the fittest loading of MgO was 1%. Under metal supported catalysts, optimum yield of n-butanol,2EH and 2-methyl-1-propanol was 11.81%,32.46% and 73.97%. Summing up the above, yield of Guerbet alcohol is higher under pure HAP catalyst than that of metal supported catalysts, but, when pure HAP as catalyst, the temperature is much higher. Finally, the mechanism was analyzed. It is a new simple and efficient procedure to prepare higher alcohol over reusable pure HAP and nickel supported HAP catalysts through a fixed-bed reactor at atmospheric pressure.The third part:Condensation of o-phenylenediamine and 1,2-diketone catalyzed by NH4HF2 to prepare quinoxaline derivatives. First, o-phenylenediamine and benzil were chosen as substrates to investigate the optimum reaction conditions. It porved that 10 mol% NH4HF2 can catalyze the condensation in methanol at room temperature during 30-45 mins, the yield is more than 92%. In addition, The single crystal structure of 2,3-Bis(4-ethoxyphenyl)quinoxaline is further established by the X-ray diffraction. It is a mild, efficient, convenient and inexpensive method to synthesis quinoxaline derivatives.The fourth part:Condensation of aldehydes and indoles to form diindolylmethane derivatives under NH4Al(SO4)2·12H2O catalyzed. It porved that 10 mol% NH4Al(SO4)2·12H2O can efficiently catalyze the condensation in methanol at room temperature.13 reactions of different aldehydes with indoles were carried out under optimum reaction conditions. The results showed that the condensation were completed within 10-200 mins in good to excellent yields(87%-98%). Aldehyde with electron donor groups is more active than aldehyde with electron withdrawing groups because of electronic effect. Finally, the possible mechanism is sketched. In conclusion, this is a mild, efficient and inexpensive method to prepare diindolylmethane derivatives.Finally, we make a conclusion to the paper and look forward to the development. Some spectras are listed, such as GC-MS for the product of Guerbet condensation of alcohols and some HNMR for target products.