Prepared under Basic Conditions

Aminomalononitrile (6), an HCN trimer, no doubt forms as an intermediate in the base-catalyzed formation of DAMN from HCN (Section II,C,1). However, its rate of formation is slower than its reaction with an additional 1 mol hydrogen cyanide. Aminomalononitrile has been synthesized from malononitrile and shown to give DAMN upon treatment with cyanide (730SC33 730SC344). 

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When the carbonyl group is very electron-deficient, thus stabilizing the hemiacetal, a dioxolane can be prepared under basic conditions. 

In the course of the previous work we have prepared compounds for comparative purposes, one of which has been reported by Gierer. He and his co-workers 15) synthesized an unsymmetrical diphenylmethane by acid-catalyzed condensation of syringyl alcohol and 2-methoxy-4-methyl-phenol and assumed substitution in the 6-position of the guaiacol nucleus. We repeated this synthesis and prepared an isomeric material by base-catalyzed condensation of the same starting materials. Our interpretation of the modes of synthesis and the NMR spectra of the two compounds is that Gierer s compound most probably is 3, 4-dihydroxy-6 -methyl-3,4, 5-trimethoxydiphenylmethane and that the compound prepared under basic conditions is 2, 4-dihydroxy-5 -methyl-3,3, 5-trimethoxydiphenylmethane, the structure claimed by Gierer. We do not, however, have unequivocal structural evidence and our data are summarized under Experimental. 

The present study focuses on the synthesis of mesostructured aluminas. In the first part of the article, the nature of the interactions between the surfactant and the inorganic framework within a sodium dodecylsulfate templated alumina is studied. The mechanism of formation of this material is also described. In the second part, the synthesis of high pore volume mesoporous alumina prepared under basic conditions is reported. 

The structure of a silica aerogel prepared under basic conditions is shown in Figure 1 (. It consists of secondary particles of about 5 nm diameter composed of smaller primary particles. Residual Si-OH and Si-OR groups are at the surface of the primary particles. 

Figure 1. Structure of a silica aerogel prepared under basic conditions. In the organically modified aerogels RxSi 2-0.5x terminal alkyl, aryl)...

Although it does not appear to have been taken up to any significant degree, one other of the many methods of analysing alkylglycerols that have been described deserves further consideration, i.e. the preparation under basic conditions of thiono-carbonate derivatives [749]. These may be estimated by their absorbance at 235 nm, and they are also suited to GC analysis (this may be also true for alk-1-enylglycerol derivatives). 

K. Hanabusa et al. have reported fibrous Ti02 with a macaroni-like structure by the sol-gel method from titanimn tetraisopropoxide using amphiphilic compound as a self-assembled template. The fibrous stmcture prepared under basic conditions was completely preserved after calcination at 450°C for 2 h (Ti02 fibers crystallized into anatase and aU organic components were removed), and this calcined samples possessed hollow structures with outer diameter of 150-600 run and iimer diameter of 50-300 nm, and the maximum length was 200 / m (Kobayashi,2000). 

Numerous methylene aceuds, especially of sugar alcohols, have been prepared [126] by treating glycols with formaldehyde in the presence of an acid catalyst. Condensations have often been effected in 40% aqueous formaldehyde solution, but paraformaldehyde and polyoxymethylene have 2dso been used as formaldehyde sources [127]. In a few cases, methylene acetals have been prepared under basic conditions from glycols and CH2Br2—NaH in dimethylformamide solution [130]. 

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