Glycols, open chain ethylene

The synthesis of 1,10-diaza-l 8-crown-6 (9) has been an important problem because this is the key starting material in the synthesis of numerous cryptands (see Chap. 8). Although first synthesized some years ago, the process has recently been patented. Di-azacrown 9 is prepared by a high dilution condensation of 1,8-diamino-3,7-dioxaoctane with ethylene glycol diacetyl chloride. The resulting diamide is then reduced with lithium aluminum hydride to give 9 in 56% overall yield from the open-chained diamine. The synthesis is illustrated In Eq. (4.8), below. 

SPOCC resin is based on the cross-linking of long-chain Poly(ethylene glycol) (PEG)terminally substituted with oxetane by cationic ring-opening polymerization. 

The only cyclic ethers that behave differently from open-chain ethers the three-membered-ring compounds called epoxides, or oxiranes. strain of the tbree-meml red ring gives epoxides unique chemical reach Ethylene oxide, the simplest epoxide, is an intermediate in the mam ture of both ethylene glycol, used for automobile antifreeze, and polyester mers. More than 4 million tons of ethylene oxide are produced each year the United States by air oxidation of ethylene over a silver oxide catalyst a SOO°C. This process is not useful for other epoxides, however, and is of littb value in the laboratory. Note that the name ethylene, oxide is not a systematie one because the -ene ending implies the presence of a double bond in the mol eculc. The name is frequently used, however, because ethylene oxide is deriva from ethylene by addition of an oxygen atom. Other simple epoxides are name similarly. The systematic name for ethylene oxide is 1,2-epoxyethane. 

Compared with the amount of organic solvent, the amount of water in the solvothermal synthesis system is little. However, it plays an extremely important role in the successful formation of the final structures. Previous studies revealed that the synthetic reaction would not happen without the presence of this small amount of water. Another direct proof showing the importance of this small amount of water is the variation of structure type crystallized from the aluminum isopropoxide-phosphoric acid-triethylamine-tetra-ethylene glycol-water (extra added) system with the variation of the amount of extra added water, keeping the other parameters constant. By a gradual increase in the amount of the extra added water, one-dimensional aluminophosphate chain, two-dimensional aluminophosphate sheet, three-dimensional aluminophosphate open-framework JDF-20 and AIPO4-5, and dense-phase cristobalite sequentially crystallized from this system under conditions of identical crystallization temperature and time. 

More recently, calcium sulfate was applied to the dehydration of glycols into unsaturated carbonyls 31), cupric sulfate mounted on alumina was used for the conversion of aUyl ether to allyl alcohol 32), and some metal sulfates were used for the open-chain polymerization of ethylene oxide 33). 

---