Neo

Gr. neos, new) Discovered by Ramsay and Travers in 1898. Neon is a rare gaseous element present in the atmosphere to the extent of 1 part in 65,000 of air. It is obtained by liquefaction of air and separated from the other gases by fractional dishhation. 

Gr. neos, new, and didymos, twin) In 1841, Mosander, extracted from cerite a new rose-colored oxide, which he believed contained a new element. He named the element didymium, as it was an inseparable twin brother of lanthanum. In 1885 von Welsbach separated didymium into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. While the free metal is in misch metal, long known and used as a pyrophoric alloy for light flints, the element was not isolated in relatively pure form until 1925. Neodymium is present in misch metal to the extent of about 18%. It is present in the minerals monazite and bastnasite, which are principal sources of rare-earth metals. 

Note the usage of the prefixes iso-, neo-, sec-, and tert-, and note when italics are employed. Italicized prefixes are never involved in alphabetization, except among themselves thus 5-ec-butyl would precede isobutyl, isohexyl would precede isopropyl, and 5-ec-butyl would precede rert-butyl. 

Changing positions of ring or chain members iso-, sec-, tert-, neo-... 

Because of the bulky neo stmcture in the middle of the molecule, this compound has enhanced hydrolytic stabiUty in addition to low volatihty. It is useful in many types of flexible foam, as well as in adhesives and epoxy- or phenoHc-based laminates. 

The boric and sulfuric acids are recycled to a HBF solution by reaction with CaF2. As a strong acid, fluoroboric acid is frequently used as an acid catalyst, eg, in synthesizing mixed polyol esters (29). This process provides an inexpensive route to confectioner s hard-butter compositions which are substitutes for cocoa butter in chocolate candies (see Chocolate and cocoa). Epichlorohydrin is polymerized in the presence of HBF for eventual conversion to polyglycidyl ethers (30) (see Chlorohydrins). A more concentrated solution, 61—71% HBF, catalyzes the addition of CO and water to olefins under pressure to form neo acids (31) (see Carboxylic acids). 

The existence of neon (Greek neos, new) was predicted, as was the existence of heavier members of the group. In 1898 krypton (Greek kTyptos, hidden) was discovered by spectroscopic examination of the residue from a sample of Hquid air. Neon was discovered in the same year. A month later, xenon (Greek xenos, strange) was isolated from the residue left after distillation of krypton. 

Biosynthesis. Three separate genes encode the opioid peptides (see Fig. 1). Enkephalin is derived from preproenkephalin A, which contains six copies of Met-enkephalin and extended peptides, and one copy of Leu-enkephalin (62—66). ( -Endorphin is one of the many products of POMC, and represents the N-terminal 31 amino acids of P-Hpotropin (67,68). Three different dynorphin peptides are derived from the third opioid gene, preproenkephalin B, or preprodynorphin (69). The dynorphin peptides include dynorphin A, dynorphin B, and a-neo-endorphin. 

The ICC classifies all three pentanes as flammable Hquids and requires that they be affixed with a red label for shipping. Because of their high vapor pressures, n- and isopentane are transported in heavy-walled dmms and neo-pentanes are transported in cylinders (see Packaging containers and INDUSTRIAL MATERIALS). 

Usually not favorable for separation of components that show similar Hquid-phase behavior, ie, steroisomers, homologous series, iso-notmA—neo isomers components to be separated must have some different functional group for MSA to affect Hquid-phase behavior differently. 

Neo acids are prepared from selected olefins using carbon monoxide and acid catalyst (4) (see Carboxylic Acids, trialkylacetic acids). 2-EthyIhexanoic acid is manufactured by an aldol condensation of butyraldehyde followed by an oxidation of the resulting aldehyde (5). Isopalmitic acid [4669-02-7] is probably made by an aldol reaction of octanal. 

Trialkylacetic acids have been produced commercially siace the early 1960s, ia the United States by Exxon and ia Europe by Shell, and have been marketed as neo acids (Exxon) or as Versatic Acids (Shell). The principal commercial products are the acid and the C q acid (neodecanoic acid, or Versatic 10), although smaller quantities of other carbon numbers, such as C, C, and C, are also produced. 

Health and Safety Factors. The C q trialkylacetic acids have toxicities similar to those for other neo acids oral LD q in rats is 2.0 g/kg, and dermal LD q in rabbits is 3.16 g/kg. 

Neo yields Properties, Chemist, and Applications, SC 82-134, Exxon Chemical Company. 

Woodward-Eschenmoser method, 4, 431-440 neo-Vitamin B,2, 4, 421 Vitamin C — see Ascorbic acid Vitamin E — see a-Tocopherol Vitamin K epoxide, 7, 119 synthesis, 1, 439 Vitamins heterocyclic... 

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