Subject hydrogen halides

Phosphoms halides are subject to reactions with active hydrogen compounds and result in the elimination of hydrogen halide. They are convenient reagents in the synthesis of many esters, amides, and related compounds. However, because the involved hydrogen halide frequendy catalyzes side reactions, it is usually necessary to employ a hydrogen halide scavenger to remove the by-product. 

Product yields in irradiated hydrogen halides are subject to the elfects of back reactions, particularly those involving the halogen molecules. These effects are most serious in the case of HC1, where a 20 % reduction in yield is observed at chlorine concentrations as low as 0.30 mole %86,88. In the more recent studies of the X- and y-radiolysis of HC1 and HBr percentage conversions were kept below 1 x 10 2 mole%. Under these conditions product yields were dose independent, showing that back reactions were negligible. 

More heavily alkylated ethylene oxides (Kq. 705) have also been subjected to the action of hydrogen halides.761- 18 1,5S-lW Mixtures of isomeric h lohydrins are undoubtedly produced, but precise quantitative data still remains to be aeoured. 

Ample results may be drawn from the sugar series on the subject of hydrogen halide addition to epoxidee, some of wbiob has only been recently found to be m error and corrected. 

A modest assortment of storoidal e -epoxy ketones (EqB. 737-740) have been subjected to the action of hydrogen halides, among them... 

When some straight and branched-chain aliphatic alcohols, such as n-propanol, n-butanol and isopropanol, are subjected to high temperatures, dehydrogenation products predominate over dehydration (51). Presumably the eliminations take place via a six-membered transition state and are catalyzed by hydrogen halides in the homogeneous phase (52) to produce olefins. On the other hand, gas phase dehydration over solid catalysts is a valuable process for the preparation of olefins and ethers. 

The net result of all these competitive reactions is a possible mixture of normal and /3-glycosides and a possible mixture of two diastereo-isomeric orthoesters. In the course of the Konigs-Knorr procedure, water is usually formed from the reaction between hydrogen halide and silver oxide. The water formed, or deliberately employed, may take the part of the solvent alcohol, thus giving rise to products such as acidic orthoesters and normal tetra- and heptaacetates (for a disaccharide) of the sugars, and these compounds are subject to further changes, such as acyl migration. 

When 1 is subjected to the carboxylate anion of 3 (TEA, R1CO2H), 2-acyloxy-l-methylpyridinium iodide (2) is formed. The hydrogen halide (HC1) is scavenged with triethylamine. A nucleophile (NuH) (4) such as an amine or alcohol in the presence of TEA adds to the carbonyl center of 2, yielding the desired product 5 and the by-product, l-methyl-2-pyridone (6). 

Alkylation by -halo ethers is of preparative interest only in special cases and is often accompanied by side reactions, e.g., loss of hydrogen halide. The subject has been reviewed several times.504... 

CHEMICAL PROPERTIES stable under ordinary conditions of use and storage undergoes acid-catalyzed hydration to yield ketones completely hydrogenated in the presence of metal hydrogenation catalysts (e.g., Pt, Pd, Ni, or Rh), yielding alkanes reacts with hydrogen halides to give alkenyl halides produces carboxylic acids when subjected to ozonolysis FP (flammable gas) LFL/UFL (1.7%, unknown) AT (unknown) HF (184.9 kJ/mol gas at 25°C). 

The most common route to sulphenes, the elimination of hydrogen halide from a sulphonyl halide, has been the subject of a recent mechanistic and kinetic study which led to the conclusion that this reaction most probably proceeds by an El mechanism. Tsuge and Iwanami used this reaction for the generation of benzoylsulphene (130) from benzoylmethane-sulphonyl chloride. The reaction of (130) with a series of anils (131) was found to be somewhat dependent on the presence or absence of triethylamine and very dependent on the nature of R in (131). For R = alkyl, the (4 -I- 2) cycloadduct (132) is the predominant or only product, whereas for R = aryl the (2 + 2) cycloadduct (133) is the reaction product. Similar results were obtained for the reaction of (130) with carbodi-imides. The reaction of (130) with aryl cinnamylideneamines gave Diels-Alder adducts (134). ... 

In adding hydrogen halides and halogens to the >C=C< double bond of 1,2-PB, the functionalization degree of the polymer is mostly determined by the reactivity of the electrophilic agent. Relatively low degree of polydiene hydrochlorination (10-15%) at interaction of HCl and syndiotactic 1,2-PB [16, 39, 40] is caused by insufficient reactivity of hydrogen chloride in the electrophilic addition reaction by the double bond (Table 3.2). Due to this, more electron-saturated >C=C< bonds in 1,4 units of butadiene polymerization are subjected to modification. 

The addition of halogen to acylaminoacrylic esters with subsequent loss of hydrogen halide to form p-halo-a-acylamino-acrylic esters has been the subject of numerous reports 198, 274, 330, 376). p-Bromo-a-acylamino-acrylic ester is also obtainable by rearrangement of N-bromo-a-acylamino-acrylic ester (378). Further reaction of the P-halo-a-acyl-aminoacrylic esters with bromine or N-bromosuccinimide and subsequent treatment with alcohol affords P,P-dihalo-a-alkoxy-a-acylaminopro-pionic acid esters 274, 379), important intermediates for biomimetic P-lactam syntheses (275). 

Metallic sodium. This metal is employed for the drying of ethers and of saturated and aromatic hydrocarbons. The bulk of the water should first be removed from the liquid or solution by a preliminary drying with anhydrous calcium chloride or magnesium sulphate. Sodium is most effective in the form of fine wire, which is forced directly into the liquid by means of a sodium press (see under Ether, Section II,47,i) a large surface is thus presented to the liquid. It cannot be used for any compound with which it reacts or which is affected by alkalis or is easily subject to reduction (due to the hydrogen evolved during the dehydration), viz., alcohols, acids, esters, organic halides, ketones, aldehydes, and some amines. 

In extending this direct method of synthesis, we next investigated the possibility of preparing similarly constituted halides from 2-deoxy-D-arabino-hexose (2-deoxy-D-glucose) (21). The hexose was subjected to a partial anomerization procedure described by Bergmann and co-workers (1). The solid material obtained by this procedure is a mixture of the anomeric forms of 2-deoxy-D-arabino-hexose low temperature p-nitro-benzoylation of the latter in pyridine resulted in a mixture of crystalline, anomeric tetrakis-p-nitrobenzoates in a ratio of approximately 1 1. They were readily separable by fractional recrystallization, and treatment of either with an excess of hydrogen bromide in dichloromethane, or with... 

In the reaction of 88 with /(-phenethyl bromide, l-phenethyl-3-phenylpropyl methyl sulfoxide and bis-3-phenylpropyl sulfoxide, besides 3-phenylpropyl methyl sulfoxide are obtained118. Sulfoxides, bearing a /1-hydrogen to the sulfmyl function, give olefins upon thermolysis. Utilizing this reaction, Trost and Bridges120 alkylated benzyl phenyl sulfoxide, 3,4-methylenedioxybenzyl phenyl sulfoxide, phenylthiomethyl phenyl sulfoxide, phenylsulfinylmethyl phenyl sulfoxide and cyanomethyl phenyl sulfoxide with alkyl, allyl and benzyl halides and subjected these sulfoxides to thermolysis, obtaining olefins in one-pot processes. 

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