Methanethiolate

Note 7. To a solution of 0.55 mol of sodium hydroxide in 150 ml of methanol and 40 ml of water was added a cold solution of 0.55 mol of methanethiol in 50 ml of methanol with cooling below 10°C. Subsequently 0.50 mol of propargyl chloride was added with swirling in 15 min, while keeping the temperature between 20 and 40°C. After an additional 30 min 1 1 of water was added and the product was extracted six times with small amounts of pentane. The extracts were washed with water, dried and the solvent was... 

The S—H bond is less polar than the O—H bond as is clearly seen m the elec trostatic potential maps of Figure 15 7 The decreased polarity of the S—H bond espe cially the decreased positive character of the proton causes hydrogen bonding to be absent m thiols Thus methanethiol (CH3SH) is a gas at room temperature (bp 6°C) whereas methanol (CH3OH) is a liquid (bp 65°C)... 

FIGURE 15 7 Electrostatic potential maps of (a) methanol and (b) methanethiol The color scales were adjusted to be the same for both molecules to allow for direct comparison The development of charge is more pronounced in the region surrounding the —OH group in methanol than it is for the —SH group in methanethiol... 

Mercury(II) oxide Chlorine, hydrazine hydrate, hydrogen peroxide, hypophosphorous acid, magnesium, phosphorus, sulfur, butadiene, hydrocarbons, methanethiol... 

Thermal Stability. Dimethyl sulfoxide decomposes slowly at 189°C to a mixture of products that includes methanethiol, formaldehyde, water, bis(methylthio)methane, dimethyl disulfide, dimethyl sulfone, and dimethyl sulfide. The decomposition is accelerated by acids, glycols, or amides (30). This product mixture suggests a sequence in which DMSO initially undergoes a Pummerer reaction to give (methylthio)methano1, which is labile and reacts according to equations 1—3. Disproportionation (eq. 4) also occurs to a small extent ... 

When DMSO is mixed with concentrated hydrochloric acid, protonated DMSO is in equiUbtium with the chlorodimethylsiilfonium ion. Pummerer reactions and subsequent reaction of the initial products give a complex mixture of products including formaldehyde, bis(methylthio)methane, methanethiol, dimethyl disulfide, dimethyl sulfide, and others. 

Methanethiol has been found in sewer gases (8,9) and is thought to be produced by the bacterial degradation of methionine. Methanethiol,... 

Skunks excrete 1-butanethiol and 2-methyl-1-butanethiol [1878-18-8] as a natural defense mechanism (12). Methanethiol is found in cheese, milk, coffee, and oysters (13—16). It is also found in the kuttin fmit, which is endemic to Southeast Asia. 

Thiols range over the gamut of physical properties. Most of the important thiols ate Hquids, however methanethiol is a gas, and 1-hexadecanethiol and 1-octadecanethiol ate waxy soflds. Tables 2 and 3 Hst a variety of physical properties for the mote important thiols. 

Methanethiol (eq. 6) and cyclohexanethiol (eq. 7) are the only commercially important thiols prepared using alcohol substitution. In most cases, when the alcohol is utilized, less control over the substitution patterns is obtained. Only one isomer is obtainable in the case of methanol and cyclohexanol. 

The main by-product of this type of reaction is the sulfide. For the synthesis of methanethiol (eq. 6), the main by-product is 2-thiapropane, CH SCH. This material has a variety of uses and is further processed. 

Decomposition of Thiols. Thiols decompose by two principal paths (i43— i45). These are the carbon—sulfur bond homolysis and the unimolecular decomposition to alkene and hydrogen sulfide. For methanethiol, the only available route is homolysis, as in reaction 29. For ethanethiol, the favored route is formation of ethylene and hydrogen sulfide via the unimolecular process, as in reaction 30. 

With a cobalt catalyst at 250°C, methanethiol (methyl mercaptan [74-93-1]) results ... 

The addition of nucleophiles to double and triple bond systems is often a convenient way of effecting an intramolecular ring closure. Addition to cyano groups has received considerable attention, as in addition to ring formation it provides a convenient method for the introduction of an amino group. Reaction of methyl Af-cyanodithiocarbimidate with Af-methylaminoacetonitrile resulted in displacement of methanethiol and formation of (314). Sodium ethoxide treatment in DMF converted (314) into a 4-amino-5-cyanoimidazole... 

Derivatives like (491 R = Me) can be de-5-methylated by Raney nickel in ethanol or concentrated hydrochloric acid. Acid hydrolysis of (491 R = acyl) also affords 5-mercap-topyrazoles, whereas alkaline hydrolysis of the pyrazolium salt (495) furnishes methanethiol and antipyrine. 

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