Lead acetate Mercaptans

The lead acetate removes any unreacted m ethyl mercaptan by precipitating it as the lead salt. 

Optically pure glyceraldehyde acetonides are widely used in the synthesis of enantiomerically pure compounds (EPC synthesis).1 2 3 4 5 Whereas D-(R)-glyceraldehyde acetonide is easily obtained from the inexpensive D-mannitol,6 7 there are only a limited number of practical syntheses of the enantiomeric L-(S)-glyceraldehyde acetonide.8 9 Difficulties arise from different sources 1) availability of the starting material diisopropylidene-L-mannitol 2) length of the synthesis 10 3) nature of the reactants used mercury acetate, mercaptans, lead tetraacetate, ozone at -78°C, 4) moderate yields.11 14... 

Laccaic acid, 537 a-Lactams, 756, 924, 8-Lactams, 234 Lactose, 61,1171 A .8( )-Lanostadiene, 151 A -Lanostene derivative, 468 Lanosterol, 916 5o-Lanosteryl 3 3-formate, 599 Laudanosine, 1106 methochloride, 1106 Laurie acid, 648-649, 666,1263, 1271 Laurone, 1199 Lauroyl azide,1041,1042 Lauroyl chloride, 1041, 1042,1199 Lauryl alcohol, 453 Lauryl bromide, 453, 1165 Lauryl mercaptan, 1165 Lazier catalyst, see Copper chromite Lead acetate trihydrate, 433,532-533 Lead dioxide, 215, 347, 409, 533-536, 537, 543, 554... 

Carbon dioxide (ASTM D-1137, ASTM D-1945, ASTM D-4984) in excess of 3% is normally removed for reasons of corrosion prevention (ASTM D-1838). Hydrogen sulfide (ASTM D-2420, ASTM D-2385, ASTM D-2725, ASTM D-4084, ASTM D-4810, IP 103, IP 272) is also removed, and the odor of the gases must not be objectionable (ASTM D-6273) so mercaptan content (ASTM D-1988, ASTM D-2385, IP 272) is important. A simple lead acetate test (ASTM D-2420, ASTM D-4084) is available for detecting the presence of hydrogen sulfide and is an additional safeguard that hydrogen sulfide not be present (ASTM D-1835). Methyl mercaptan, if present, produces a transitory yellow stain on the lead acetate paper that fades completely in less than 5 min. Other sulfur compounds (ASTM D-5504, ASTM D-6228) present in liquefied petroleum gas do not interfere. 

Lauryl mercaptan, 21, 36 S-Laurylthiuronium bromide, 21, 37 Lauryl -toluenesuleonate, 20, SO Lead acetate, 24, 62... 

Lead acetate/triethylamine Trithiocarbonic acid esters from mercaptans and carbon disulfide... 

Dodecylbenzene Dodecyl Sulfate, Magnesium Salt Lauryl Mercaptan Dodecyl Sulfate, Sodium Salt Dodecyl Sulfite, Magnesium Salt Dodecyl Sulfate, Sodium Salt Docecyl Sulfate, Triethianolamine Salt Lead Tetraacetate Lead Acetate Lead Acetate Lead Arsenate... 

The most important oxidants in glacial acetic acid as solvent are lead tetraacetate, which oxidizes mercaptans RSH to disulfide RSSR cerium(rv), a strong oxidant, though its reactions tend to be slow iodobenzene dichlorideand bromine, which may be obtained conveniently by coulometric generation. 

Aq.-alc. lead (II) acetate added dropwise to an ethanolic soln. of dodecyl mercaptan, triethylamine, and excess CSg, refluxed overnight didodecyl tri-thiocarbonate. Y 88%. Also isolation of intermediates s. M. Kiessel and D. Braun, B. 98, 1350 (1965). 

A method of degradation with excellent preparative possibilities has been devised by MacDonald and Fischer (200), The higher-carbon sugar first is condensed with ethyl mercaptan to form the bis(ethylthio)acetal (mercaptal) (I) (Chapter IV). Oxidation of the mercaptal with perpro-pionic acid then leads to the bis(ethylsulfonyl) compound (II), which is smoothly degraded by aqueous ammonia to the next lower aldose and bis(ethylsulfonyl)methane. 

Treatment of poly(vinyl alcohol) with chloroacetaldehyde gave a cyclic acetal with a replaceable chloride (XLI). Reaction with KSH or thiourea followed by saponification gave a polythiol (53,56) (XLII). This approach could lead to hydrophilic polymers with readily accessible mercaptan groups if the initial acetalization is limited to 10% reaction. Polymers of this type would be useful as enzyme supports. 

The irreversible reactions of amines with O2, CO2, COS, and CS2 are discussed in the preceding sections. The principal other potentially reactive gas phase impurities which may enter the absorber are organic acids (such as formic or acetic acids), HCl, HCN, SO2, NH3, and mercaptans. All of the acidic compounds form salts with the alkaline amines. If the acids are stronger than CO2 and H2S, their amine salts are not efficiently decomposed under the stripping conditions (which are designed to decompose the amine-C02 and amine-H2S salts), and they build up in the solution as heat-stable amine salts (HSAS). This, of course, lowers the capacity of the solution for CO2 and H2S, and can lead to other operational difficulties such as corrosion and foaming. Caustic soda or soda ash is often added to the solution to tie up the acids as sodium salts and release the amine however, sodium salt build up... 

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