Acid bromides reduction

Bromide ndIodide. The spectrophotometric determination of trace bromide concentration is based on the bromide catalysis of iodine oxidation to iodate by permanganate in acidic solution. Iodide can also be measured spectrophotometricaHy by selective oxidation to iodine by potassium peroxymonosulfate (KHSO ). The iodine reacts with colorless leucocrystal violet to produce the highly colored leucocrystal violet dye. Greater than 200 mg/L of chloride interferes with the color development. Trace concentrations of iodide are determined by its abiUty to cataly2e ceric ion reduction by arsenous acid. The reduction reaction is stopped at a specific time by the addition of ferrous ammonium sulfate. The ferrous ion is oxidi2ed to ferric ion, which then reacts with thiocyanate to produce a deep red complex. 

Pletcher and associates [155, 159, 160] have studied the electrochemical reduction of alkyl bromides in the presence of a wide variety of macrocyclic Ni(II) complexes. Depending on the substrate, the mediator, and the reaction conditions, mixtures of the dimer and the disproportionation products of the alkyl radical intermediate were formed (cf. Section 18.4.1). The same group [161] reported that traces of metal ions (e.g., Cu2+) in the catholyte improved the current density and selectivity for several cathodic processes, and thus the conversion of trichloroacetic acid to chloroacetic acid. Electrochemical reductive coupling of organic halides was accompanied several times by hydrodehalogena-tion, especially when Ni complexes were used as mediators. In many of the reactions examined, dehalogenation of the substrate predominated over coupling [162-165]. 

Acid chlorides, reduction to aldehydes, 53, 55 Acid chlorides, aromatic, diazoketones from, 53, 37 Acrylic acid, with p-acetyl-benzenediazonium bromide,... 

Concentrated hydrochloric acid also dissolves the trichloride, about 100 g. of the latter dissolving in 1 litre of acid at 100° C.7 Dissolution in hydriodic acid is accompanied by evolution of heat and the triiodide is formed.8 Ethyl iodide reacts similarly.9 Double decomposition reactions occur w hen arsenic trichloride is heated with phosphorus triiodide, stannic iodide or germanium iodide, the reactions being complete.10 Similarly, potassium iodide heated with arsenic trichloride in a sealed tube at 210° C., and potassium bromide at 180° to 200° C., form respectively arsenic triiodide and tribromide.11 Stannous chloride, added to the solution in hydrochloric acid, causes reduction to arsenic (see p. 29). Arsenic trichloride may be completely separated from germanium chloride by extraction with concentrated hydrochloric acid.12 Ammonium, sodium and cobaltic chlorides react with arsenic trichloride to form additive compounds with magnesium, zinc and chromic chlorides there is no reaction.13... 

Adipic acid has been prepared by the following methods the action of silver1 or copper 2 on /3-iodopropionic acid the reduction of mucic add with phosphorus and iodine 3 the electrolysis of the potassium or sodium salts of monoethyl succinate 4 the condensation of ethylene chloride or bromide with malonic ester or cyanoacetic ester and subsequent hydrolysis 5 the oxidation of certain fractions of Baku petroleum 6 the oxidation of cyclohexanol or cyclohexanone with nitric acid 7 or potassium permanganate.8... 

Indium (I) halides can be prepared by dissolving an excess of indium in hydrohalide acid or reduction of trUialides with metal. The structures of the bromides have been... 

Octahydro- (we have used this nomenclature throughout) or perhydrobenzo[c]thiophene (35) exists as the cis and trans isomers and is more commonly named 2-thiahydrindane or 8-thiabicyclo-[4.3.0]nonane. Each stereoisomer may be prepared by treating the corresponding isomer of l,2-di(bromomethyl)cyclohexane with sodium sulfide (details of the products are given in Table IV).45 Cyclization of the cis isomer may be effected partially with thiourea via the formation of cis-hexahydro-o-xylylenebis(isothiouronium bromide) with sodium disulfide it gives a mixture of cis-octahydro-benzo[c]thiophene and cis-2,3-dithiadecalin.46 Optically pure ( —)-(8 R,9I )-lran -octahydrobenzo[c]thiophene has been prepared from (+ )-dicarboxylic acid via reduction of the diacid to the diol, tosylation, and ring closure of the bistosylate with sodium sulfide.47... 

The ready formation of esters of P amino acids by reduction of the correspond ing imines/enamines (Table 4.6, entries 12 14), which in turn can be prepared from the readily available P keto esters, allowed an expedient synthesis of SCH48461 (56), a potent, orally active inhibitor of cholesterol absorption [22]. Enamine 36n (Scheme 4.6) was reduced (via imine lOn) with ChSiH in the presence of Sigamide (35) to afford the P amino ester ISn (80% isolated yield, 88% ee), whose treatment with methylmagnesium bromide (acting as a base) produced p lactam 55 (92%). Enolization of the latter derivative with LDA followed by alkylation with cinnamyl bromide and catalytic hydrogenation afforded 56 in 77% overall yield for the last two steps (S. Stoncius, A.V. Malkov, and P. Kocovsky, unpublished results). 

Disulfides are obtained from sulfinic acids on reduction by hydrogen bromide in acetic acid solution 553,555-557... 

Amidation of 203 followed by partial hydrolysis affords D-jS-malamic acid (899). Reduction of 899 with diborane furnishes (R)-4-amino-l,2-butanediol (900). Protection of the amine with a Cbz group and conversion of the primary alcohol to a bromide leads to the critical intermediate 901. Alkylation of lysine derivative 902 with 901 and removal of the protecting groups under hydrogenolytic conditions gives hypusine (903). 

The synthesis of hepialone (928), the principal sex pheromone produced by the male moth Hepaialus californicus, relies on (7 )-1,2-epoxybutane (925) as the source of chirality (Scheme 136) [204]. Epoxide 925 is in turn synthesized from (7 )-malic acid by reduction of the THP derivative 921b with lithium aluminum hydride and conversion of diol 922 to ditosylate 923 and then dibromide 924. Removal of the protecting group followed by base-catalyzed cyclization results in epoxide formation. Debromination of the primary bromide with tri-n-butyltin hydride affords the desired oxirane 925. 

LI by reaction with y-ethoxypropylmagnesium bromide. Reduction to the piperidyl carbinol LII was followed by treatment with hydriodic acid. The base produced, CxoHuN, formed a picrate, m.p. 163 , and an aurichloride, m.p. 142-143 . The melting points were undepressed when the derivatives were mixed with the corresponding derivatives of inactive /3-lupinane (XV) obtained from natural lupinine (120). The total synthesis of lupinine itself was achieved somewhat later by Clemo, Morgan, and Raper (146, 147). 

The technical breakthrough was however only attained with the StoU-Hansley-Prelog procedure for the synthesis of exaltone. By reaction with sodium, dimethyl hexadecanedioate was converted into the acyloin, [174] the reduction of which with zinc and hydrochloric acid (Qemmensen reduction) gave exaltone. On the other hand, dehydration of the acyloin over hot aluminium oxide gave exaltenone, which could be converted by a copper(I)-catalysed reaction with methylmagnesium bromide into (+/-)-muscone. 

In general, these compounds were synthesized from appropriately substituted and selectively protected phenolic esters. A reaction sequence that consisted of selective deprotection, oxidation to the quinoid system, and addition of an amino acid gave vinylogous esters. Linkage to the trans-decalin building blocks with an exocyclic double bond was achieved with a Suzuki coupling of substituted arylboronic acids to the corresponding decalin-derived vinyl bromides. Reduction of... 

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