Crystals synthesis

Jones, A.G., Ejaz, T. and Graham, P., 1999. Direct dynamic observation of phase transformations during zeolite crystal synthesis. In Industrial Crystallization 99. (Rugby Institution of Chemical Engineers). Cambridge, 13-15 September 1999. Paper 95, p. 98. 

The present method is successful with a wide variety of ketones (see Table). Cyclic ketones (entries 1-4, 8) produce benzoannelated products in excellent overall yields. There is no need to purify the intermediate both the nucleophilic addition of methallylmagnesium chloride and the aromatic cyclization take place cleanly. Acyclic ketones (entries 5-7) also provide high yields of benzoannelated product. Aromatic ketones are particularly interesting substrates for this reaction since they provide substituted biphenyls, which are potentially useful materials for liquid crystal synthesis and whose preparation through classical methodology is often not straightforward. The conditions for the cationic cyclization step can be modified to accommodate acid-sensitive functionality. For example, cyclization of 3 to 4, the latter a precursor for 3-methyl-8,14-dehydromorphinan, was accomplished in 77% yield by treatment of 3 at... 

Investigations into the influence of composition on hardness play an especially important role in mixed crystal synthesis processes. Subramanian and Bansigir (1980) synthesized a series of mixed optical crystals KCl-KBr (Fig. 5.17). They demonstrated a definite influence of mole composition on crystal hardness and the absence of a strict correlation between hardness and dislocation density in the crystals obtained in the process. The maximum number of dislocations involved pure crystals of both compounds, each exhibiting minimum hardness. 

Goals in liquid crystal synthesis include the design of room temperature thermotropics which are stable, colorless liquid crystalline over a wide range of temperature, and operate at low voltage and power levels. 

Kiryanov, A.A., Sampson, R and Seed, A.J., Synthesis of 2-alkoxy-substituted thiophenes, 1,3-thiazoles, and related S-heterocycles via LawessoiTs reagent-mediated cyclization under microwave irradiation applications for liquid crystal synthesis, /. Org. Chem., 2001, 66, 7925-7929. 

Gudel and coworkers have reported during recent years many cases of (near) infrared emission from several transition-metal ions. This was only possible by the use of suitable detectors of radiation (e.g. a cooled germanium photo-detector) and careful crystal synthesis. Here we mention some examples. 

Mortko, C.J. and Garcia-Garibay, M.A. (2006) Engineering stereospecific reactions in crystals synthesis of compounds with adjacent stereogenic quaternary centers by photodecarbonylation of crystalline ketones, in Topics in Stereochemistry, Vol. 25 (eds S.E. Denmark and J.S. Siegel), John Wiley Sons, Hoboken, NJ, pp. 205—253. 

A valuable example of the assessment of a failed or unreliable strategy for crystal synthesis can be found in Ref. 51a. The issue is also raised in Ref. 27a. 

Supported zeolite membranes have been prepared using numerous procedures [4] such as alignment of crystals in electrical fields, electroplating, self-assembly, growth on organic molecular layers, covalent linkages, hydrothermal synthesis (in situ and ex situ), hydrothermal method microwave heating assisted, dry gel method (vapor-phase transport method and steam-assisted crystallization), synthesis at the interface between two fluid phases, etc. 

Kumar S, Pal SK (2005) Ionic discotic liquid crystals synthesis and characterization of pyridinium bromides containing a triphenylene core. Tetrahedron Lett 46 4127-4130... 

Diffraction is the key experimental technique in crystal engineering. It provides the means of accurately characterising the product of a crystal synthesis endeavor. However, the applications of diffraction are much wider than simply structure determination. An overview of the contribution of crystallography to many areas of chemistry is provided in a recent issue of the journal Chemical Society Reviews dedicated to crystallography [49]. The purpose of this chapter has been to take a broader view of diffraction studies and their present and future potential to play an important role in the continued development of all aspects of crystal engineering. 

Applications of this method include among others the preparation of unsym-metrical diaryldiynes [27] and of l,4-bis[2-(4 ,4"-dialkoxyphenyl)ethenyl]benzenes for polymer [28] and liquid-crystal synthesis [29]. Such one-pot acetylene double couplings are also possible between (substituted) 6-bromoazalenes and substituted bromobenzenes [30], and even macrocyclic polyenepolyynes have been made in this way ([31, 32], Scheme 3). 

Styring, P., Towards liquid crystal synthesis using high throughput and micro reactor technologies. Mol. Cryst. Liq. Cryst., 411,2004,1059-1070. 

---