1- dodecanethiol

Handling, Storage, and Precautions solid material should be stored under refrigeration in a closed bottle. Solutions will slowly oxidize in the presence of air to the cyclic disulfide, which is inert. The concentration of reduced material can be determined by assay with 5,5 -dithiobis(2-nitrobenzoate).  

The high equilibrium constant for this cyclization reaction produces the low redox potential for DTT. The hydroxy groups at C-2 and C-3 convey water solubility and reduce the stench (the solid has an odor, but only at very close range). Since the active form for disulfide interchange is the thiolate anion, these reactions go faster at higher pH. With the first p/(at 9.2, however, there is sufficient thiolate even at pH 7 to give a reasonable rate. 

The rates of reduction of disulfides by DTT show a normal dependence on the Koi the thiol being liberated, and this fact has been used to determine the p/Ts of SH groups on proteins. For example, the of the active site cysteine in papain was 4.1 at pH 6 and 8.4 at pH 9, with the change resulting from a group titrating with a of 7.5. The equation used in this work was log k= 7.03 + 0.5 p7i(nuc — 0.27 p/i — 0.73 p/Cig, where the rate constant in min for reaction of the monoanion of DTT with the disulfide, and the subscripts nuc, c, and Ig refer to DTT, the center sulfur in the transition state, and the leaving thiol on the protein. 

A series of other dithiols have been prepared as potential reducing agents, but none of them that are water soluble have lower redox potentials than DTT. P Two that have lower pA s (7.6-7.8) and thus react faster at neutral pH have higher redox potentials of —0.27 V at pH 7 and are less effective reducing agents than DTT. 13 So far, none of these is commercially available. 

Other Properties and Problems. The low redox potential of dithiothreitol interferes with its use in the presence of certain reagents. While it gives full color yield in reactions with aromatic disulfides such as 5,5 -dithiobis(2-nitrobenzoate) or 2,2 - or 4,4 -dipyridyl disulfide, gives only 4% the expected color in the nitroprusside assay for thiols, presumably because it reduces the iron. It reduces Ci or Co , complexes of nucleotides 

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The principal impetus behind the synthesis of thiols came from the need to produce synthetic mbber in the early 1940s. These mbbers, styrene—butadiene mbbers (SBRs), were produced by many companies at that time. Originally, 1-dodecanethiol was utilized, but the most important thiol became / fZ-dodecanethiol, which was made from propylene tetramer, using an acid-catalyzed process (54,55). 

Chemical Designations - Synonyms 1-Dodecanethiol Dodecyl mercaptan Chemical Formula CH3(CHi)i(,CHiSH. 

To avoid these stability problems, it is necessary to minimize the proportion of chains that terminate by radical-radical reaction. One way of achieving this is to conduct the polymerization in the presence of an appropriate chain transfer agent. For example, if polymerization is performed in the presence of a H-donor chain transfer agent, conditions can be chosen such that most chains terminate by hydrogen-atom transfer. Bagby et al.iA examined the thermal stability of PMMA formed with dodecanethiol. These polymer chains will then possess, more... 

The low reactivity of alkyl and/or phenyl substituted organosilanes in reduction processes can be ameliorated in the presence of a catalytic amount of alkanethiols. The reaction mechanism is reported in Scheme 5 and shows that alkyl radicals abstract hydrogen from thiols and the resulting thiyl radical abstracts hydrogen from the silane. This procedure, which was coined polarity-reversal catalysis, has been applied to dehalogenation, deoxygenation, and desulfurization reactions.For example, 1-bromoadamantane is quantitatively reduced with 2 equiv of triethylsilane in the presence of a catalytic amount of ferf-dodecanethiol. 

This approach has been recently extended to the reduction of aromatic azides using EtsSiH, which afford anilinosilanes and hence the corresponding anilines in virtually quantitative yields (Reaction 38). The EtsSi radical adds to the aromatic azido group to give an N-silylarylaminyl radical presumably through loss of nitrogen. Eventual reduction of the silylarylaminyl radical by ferf-dodecanethiol affords N-silylaniline 31, the hydrolytic precursors of the final anilines. 

FIG. 11 TEM images of 2.8-nm-diameter silver particles capped by dodecanethiol that were horizontally transferred from the water surface at a surface pressure just below that at which the film would collapse. The top figure is a higher-resolution image of this phase of particles. (Reprinted with permission from Ref. 121. Copyright 1997 American Chemical Society.)... 

The tip-particle distance, using (Vbias = 1 V, /tmmei = 1 nA) as tunnel parameters does not correspond to that needed to observe the Coulomb staircase. The particle-substrate distance is fixed by the coating with dodecanethiol. Hence the two tunnel junctions are characterized by fixed parameters. Similar Coulomb blockade behavior has been observed [58,59]. 

In an attempt to create particles with different sizes and properties, ligands other than dodecanethiol were used to create polydispersed colloids from the SMAD method. Thus, dodecylamine, trioctyl phosphine, and dodecyl alcohol were used in addition to dodecanethiol. The results of these studies led to nearly monodispersed stable colloids for the phosphine protected particles at 6.3 nm in diameter (Figure 13). 

Figure 22. TEM micrographs of digestively ripened Au colloids prepared by the inverse micelle method with (a) octanethiol, (b) decanethiol, (c) dodecanethiol, and (d) hexadecanethiol. (Reprinted with permission from Ref [49], 2002, American Chemical Society.)...

In 2001, we developed a simple and quite useful method to manipulate the size of Au nanoparticles by using the heat-treatment of small Au nanoparticles [9,10], which is far from the conventional techniques. The 1-dodecanethiol-protected Au nanoparticles (C12S-AU) of 1.5 0.2 nm in size synthesized by the Brust s two-phase (toluene/water) reaction procedure [3] were heat treated at 150-250 °C at the heating rate of 2°Cmin and held for 30min. This heat treatment of as-synthesized C12S-AU nanoparticles... 

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