1,2-Adducts, metallated

Under the action of strong organometallic bases, thiazole undergoes hydrogen-metal interconversion. Ethylmagnesium bromide reacts at 0°C with thiazole in ether to form an insoluble adduct that upon heating evolves ethane almost quantitatively and affords an etheral solution of thiazol-2-ylmagnesium bromide (155) (12). Proof of the structure of this... 

Hydrazine—borane compounds are made by the reaction of sodium borohydride and a hydrazine salt in THF (23,24). The mono-(N2H4 BH ) and di-(N2H4 2BH2) adducts are obtained, depending on the reaction conditions. These compounds have been suggested as rocket fuels (25) and for chemical deposition of nickel—boron alloys on nonmetallic surfaces (see Metallic COATINGS) (26). 

DiphenyhnethyUithium [881-42-5] can be prepared by the metalation reaction of butyUithium with diphenyknethane in addition, the adduct of butyUithium and 1,1-diphenylethylene is convenientiy prepared in either hydrocarbon or polar solvents such as THF as shown in equation 18. 

MIBK is a highly effective separating agent for metals from solutions of their salts and is used in the mining industries to extract plutonium from uranium, niobium from tantalum, and zirconium from hafnium (112,113). MIBK is also used in the production of specialty surfactants for inks (qv), paints, and pesticide formulations, examples of which are 2,4,7,9-tetramethyl-5-decyn-4,7-diol and its ethoxylated adduct. Other appHcations include as a solvent for adhesives and wax/oil separation (114), in leather (qv) finishing, textile coating, and as a denaturant for ethanol formulations. 

Another method for producing petoxycatboxyhc acids is by autoxidation of aldehydes (168). The reaction is a free-radical chain process, initiated by organic peroxides, uv irradiation, o2one, and various metal salts. It is terrninated by free-radical inhibitors (181,183). In certain cases, the petoxycatboxyhc acid forms an adduct with the aldehyde from which the petoxycatboxyhc acid can be hberated by heating or by acid hydrolysis. If the petoxycatboxyhc acid remains in contact with excess aldehyde, a redox disproportionation reaction occurs that forms a catboxyhc acid ... 

Overlay Proofing. Overlay proofing systems can be categorized as wet- or dry-processed systems. The negative working wet-processed systems are generally composed of polymeric diazo resin salts (haUdes or heavy metal), which after photolysis form an insoluble adduct. 

Most commercial sorbic acid is produced by a modification of this route. Catalysts composed of metals (2inc, cadmium, nickel, copper, manganese, and cobalt), metal oxides, or carboxylate salts of bivalent transition metals (2inc isovalerate) produce a condensation adduct with ketene and crotonaldehyde (22—24), which has been identified as (5). 

Heating the adduct of ethylene oxide and sulfur dioxide with primary alcohols in the presence of alkaH hydhdes or a transition-metal haHde yields dialkyl sulfites (107). Another method for the preparation of methyl alkyl sulfites consists of the reaction of diazomethane with alcohoHc solutions of sulfur dioxide (108). 

Ionic polymers are also formulated from TDI and MDI (43). Poly(urethane urea) and polyurea ionomers are obtained from divalent metal salts of /)-aminohen2oic acid, MPA, dialkylene glycol, and 2,4-TDI (44). In the case of polyureas, the glycol extender is omitted. If TDI is used in coatings apphcations, it is usually converted to a derivative to lower the vapor pressure. A typical TDI prepolymer is the adduct of TDI with trimethyl olpropane (Desmodur L). Carbodiimide-modified MDI offers advantages in polyester-based systems because of improved hydrolytic stabihty (45). Moisture cure systems based on aromatic isocyanates are also available. 

Hydrogen haHde addition to vinyl chloride in general yields the 1,1-adduct (50—52). The reactions of HCl and hydrogen iodide [10034-85-2], HI, with vinyl chloride proceed by an ionic mechanism, while the addition of hydrogen bromide [10035-10-6], HBr, involves a chain reaction in which a bromine atom [10097-32-2] is the chain carrier (52). In the absence of a transition-metal catalyst or antioxidants, HBr forms the 1,2-adduct with vinyl chloride (52). HF reacts with vinyl chloride in the presence of stannic chloride [7646-78-8], SnCl, to form 1,1-difluoroethane [75-37-6] (53). 

Because of the presence of an extended polyene chain, the chemical and physical properties of the retinoids and carotenoids are dominated by this feature. Vitamin A and related substances are yellow compounds which are unstable in the presence of oxygen and light. This decay can be accelerated by heat and trace metals. Retinol is stable to base but is subject to acid-cataly2ed dehydration in the presence of dilute acids to yield anhydrovitamin A [1224-18-8] (16). Retro-vitamin A [16729-22-9] (17) is obtained by treatment of retinol in the presence of concentrated hydrobromic acid. In the case of retinoic acid and retinal, reisomerization is possible after conversion to appropriate derivatives such as the acid chloride or the hydroquinone adduct. Table 1 Hsts the physical properties of -carotene [7235-40-7] and vitamin A. 

The synthesis of dehydro-hnalool (28) rehes on the basic chemicals acetone and acetjiene. Addition of a metal acetyUde to acetone yields methylbutynol (33). Semihydrogenation affords the alkene (34) which is reacted with /-propenylmethyl ether. A Cope rearrangement of the adduct yields methyUieptenone (35). Addition of a second mole of metal acetyUde to dehydro-linalool (28) is followed by a second Cope rearrangement to yield... 

The isophytol side chain can be synthesized from pseudoionone (Fig. 5) using chemistry similar to that used in the vitamin A synthesis (9). Hydrogenation of pseudoionone (20) yields hexahydropseudoionone (21) which can be reacted with a metal acetyUde to give the acetylenic alcohol (22). Rearrangement of the adduct of (22) with isopropenyknethyl ether yields, initially, the aHenic ketone (23) which is further transformed to the C g-ketone (24). After reduction of (24), the saturated ketone (25) is treated with a second mole of metal acetyUde. The acetylenic alcohol (26) formed is then partially hydrogenated to give isophytol (14). 

Zirconium tetraiodide is the least thermally stable zirconium tetrahaUde. At 1400°C, it disproportionates to Zr metal and iodine vapor. This behavior is utilized in the van Arkel-de Boer process to refine zirconium. As with the tetrachloride and tetrabromide, the tetraiodide forms additional adducts with gaseous ammonia which, upon heating, decompose through several steps ending with zirconium nitride. 

Derivatives of Antimony Pentabromide and Pentaiodide. The existence of SbBr and Sbl is in doubt, although from time to time they are reported in the Hterature (35). The existence of a 1 1 adduct, SbBr 0(0244 )2, however, is generally accepted. In addition, the SbBr ion is known, and from x-ray studies has been found to have a slightly distorted octahedral stmcture (36). Indeed, there are quite a number of complex bromoantimony compounds with alkali metals and organic bases, some of wliich contain Sb(V). Thus the quinuclidinium salt (C24423N44)4Sb2Br2g is actually made up of... 

Future Methods. A by-product stream containing 60—80% PEA can be obtained from the catalytic air oxidation of ethylbenzene [100-41-4] (100). Perfumery-grade material can be isolated from this stream by complexing the PEA with a metal haUde (such as CaCl2), separation of the adduct, and thermal decomposition followed by distillation. 

Complex Formation. B-Ttichlorobora2iQe was reported to readily form crystalline adducts of uncertain stmcture with pyridine (131). The Lewis acids aluminum tribromide or gallium trichloride form 1 1 adducts with hexamethylbota2iQe (eq. 36) ia which the metal atom coordinates with a nitrogen with loss of planarity of the ring (132,133). 

A number of disinfectants apparentiy owe their activity to formaldehyde, although there is argument on whether some of them function by other mechanisms. In this category, the dmg with the longest history is hexamethylenetetramine (hexamine, urotropin) [100-97-0] which is a condensation product of formaldehyde and ammonia that breaks down by acid hydrolysis to produce formaldehyde. Hexamine was first used for urinary tract antisepsis. Other antimicrobials that are adducts of formaldehyde and amines have been made others are based on methylolate derivations of nitroalkanes. The apphcations of these compounds are widespread, including inactivation of bacterial endotoxin preservation of cosmetics, metal working fluids, and latex paint and use in spin finishes, textile impregnation, and secondary oil recovery (117). 

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