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Sulfonium
In organic chemistry, a sulfonium ion, also known as sulphonium ion or sulfanium ion, is a positively-charged ion (a " cation") featuring three organic substituents attached to sulfur. These organosulfur compounds have the formula . Together with a negatively-charged counterion, they give sulfonium salts. They are typically colorless solids that are soluble in organic solvent. Synthesis Sulfonium compounds are usually synthesized by the reaction of thioethers with alkyl halides. For example, the reaction of dimethyl sulfide with iodomethane yields trimethylsulfonium iodide: : + → The reaction proceeds by a nucleophilic substitution mechanism (SN2). Iodide is the leaving group departs. The rate of methylation is faster with more electrophilic methylating agents, such as methyl trifluoromethanesulfonate. Inversion Sulfonium ions with three different substituents are chiral owing to their pyramidal structure. Unlike the isoelectronic oxonium ions (R3O+), chiral sulfon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethylsulfonium Iodide
Trimethylsulfonium (systematically named trimethylsulfanium and trimethylsulfur(1+)) is an organic chemistry, organic cation with the chemical formula (CH3)3S+ (also written as ). Compounds Several salt (chemistry), salts of trimethylsulfonium are known. X-ray crystallography reveals that the sulfur is pyramidal, with C-S-C angles near 102° and C-S bond distance of 177 picometers. Unless the anion is colored, all trimethylsulfonium salts are white or colorless. Preparation Sulfonium compounds can be synthesised by treating a suitable alkyl halide with a thioether. For example, the reaction of dimethyl sulfide with iodomethane yields trimethylsulfonium iodide: :CH3–S–CH3 + CH3–I → (CH3)3SI Related An extra oxygen atom can bond to the sulfur atom to yield the trimethylsulfoxonium ion. Use Glyphosate herbicide is often supplied as a trimethylsulfonium salt. When mixed with aluminium bromide, or aluminium chloride or even hydrogen bromide, trimethylsulfonium bromide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfonium Compounds
In organic chemistry, a sulfonium ion, also known as sulphonium ion or sulfanium ion, is a positively-charged ion (a "cation") featuring three organic substituents attached to sulfur. These organosulfur compounds have the formula . Together with a negatively-charged counterion, they give sulfonium salts. They are typically colorless solids that are soluble in organic solvent. Synthesis Sulfonium compounds are usually synthesized by the reaction of thioethers with alkyl halides. For example, the reaction of dimethyl sulfide with iodomethane yields trimethylsulfonium iodide: : + → The reaction proceeds by a nucleophilic substitution mechanism (SN2). Iodide is the leaving group departs. The rate of methylation is faster with more electrophilic methylating agents, such as methyl trifluoromethanesulfonate. Inversion Sulfonium ions with three different substituents are chiral owing to their pyramidal structure. Unlike the isoelectronic oxonium ions (R3O+), chiral sulfonium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organosulfur Compound
Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur is vital for life. Of the 20 common amino acids, two ( cysteine and methionine) are organosulfur compounds, and the antibiotics penicillin and sulfa drugs both contain sulfur. While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur compounds, the removal of which is a major focus of oil refineries. Sulfur shares the chalcogen group with oxygen, selenium, and tellurium, and it is expected that organosulfur compounds have similarities with carbon–oxygen, carbon–selenium, and carbon–tellurium compounds. A classical chemical test for the detection of sulfur co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onium Compounds
In chemistry, an onium ion is a cation formally obtained by the protonation of mononuclear parent hydride of a pnictogen (group 15 of the periodic table), chalcogen (group 16), or halogen (group 17). The oldest-known onium ion, and the namesake for the class, is ammonium, , the protonated derivative of ammonia, . The name onium is also used for cations that would result from the substitution of hydrogen atoms in those ions by other groups, such as organic radicals, or halogens; such as tetraphenylphosphonium, . The substituent groups may be divalent or trivalent, yielding ions such as iminium and nitrilium. A simple onium ion has a charge of +1. A larger ion that has two onium ion subgroups is called a double onium ion, and has a charge of +2. A triple onium ion has a charge of +3, and so on. Compounds of an onium cation and some other anion are known as onium compounds or onium salts. Onium ions and onium compounds are inversely analogous to ions and ate complexes: *Lewis bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoacid
Photoacids are molecules which become more acidic upon absorption of light. Either the light causes a photodissociation to produce a strong acid or the light causes photoassociation (such as a ring forming reaction) that leads to an increased acidity and dissociation of a proton. There are two main types of molecules that release protons upon illumination: photoacid generators (PAGs) and photoacids (PAHs). PAGs undergo proton photodissociation irreversibly, while PAHs are molecules that undergo proton photodissociation and thermal reassociation. In this latter case, the excited state is strongly acidic, but reversible. Photoacid generators An example due to photodissociation is triphenylsulfonium triflate. This colourless salt consists of a sulfonium cation and the triflate anion. Many related salts are known including those with other noncoordinating anions and those with diverse substituents on the phenyl rings. The triphenylsulfonium salts absorb at a wavelength of 233&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylsulfonium Triflate
Photoacids are molecules which become more acidic upon absorption of light. Either the light causes a photodissociation to produce a strong acid or the light causes photoassociation (such as a ring forming reaction) that leads to an increased acidity and dissociation of a proton. There are two main types of molecules that release protons upon illumination: photoacid generators (PAGs) and photoacids (PAHs). PAGs undergo proton photodissociation irreversibly, while PAHs are molecules that undergo proton photodissociation and thermal reassociation. In this latter case, the excited state is strongly acidic, but reversible. Photoacid generators An example due to photodissociation is triphenylsulfonium triflate. This colourless salt consists of a sulfonium cation and the triflate anion. Many related salts are known including those with other noncoordinating anions and those with diverse substituents on the phenyl rings. The triphenylsulfonium salts absorb at a wavelength of 233&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TASF Reagent
The TASF reagent or tris(dimethylamino)sulfonium difluorotrimethylsilicate is a reagent in organic chemistry with structural formula (CH3)2N)3Ssup>+ 2Si(CH3)3sup>−. It is an anhydrous source of fluoride and is used to cleave silyl ether protective groups. Many other fluoride reagents are known, but few are truly anhydrous, because of the extraordinary basicity of "naked" F−. In TASF, the fluoride is masked as an adduct with the weak Lewis acid trimethylsilylfluoride (FSi(CH3)3). The sulfonium cation ((CH3)2N)3S+ is unusually non-electrophilic due to the electron-donating properties of the three (CH3)2N substituents. This compound is prepared from sulfur tetrafluoride: :3 (CH3)2NSi(CH3)3 + SF4 → 2 (CH3)3SiF + (CH3)2N)3Ssup>+ 2Si(CH3)3sup>− The colorless salt precipitates from the reaction solvent, diethyl ether. Structure The cation (CH3)2N)3Ssup>+ is a sulfonium ion. The S-N distances are 1.612 and 1.675 pm. The N-S-N angles are 99.6°. The anion is 2Si(CH ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TASF
The TASF reagent or tris(dimethylamino)sulfonium difluorotrimethylsilicate is a reagent in organic chemistry with structural formula (CH3)2N)3Ssup>+ 2Si(CH3)3sup>−. It is an anhydrous source of fluoride and is used to cleave silyl ether protective groups. Many other fluoride reagents are known, but few are truly anhydrous, because of the extraordinary basicity of "naked" F−. In TASF, the fluoride is masked as an adduct with the weak Lewis acid trimethylsilylfluoride (FSi(CH3)3). The sulfonium cation ((CH3)2N)3S+ is unusually non-electrophilic due to the electron-donating properties of the three (CH3)2N substituents. This compound is prepared from sulfur tetrafluoride: :3 (CH3)2NSi(CH3)3 + SF4 → 2 (CH3)3SiF + (CH3)2N)3Ssup>+ 2Si(CH3)3sup>− The colorless salt precipitates from the reaction solvent, diethyl ether. Structure The cation (CH3)2N)3Ssup>+ is a sulfonium ion In organic chemistry, a sulfonium ion, also known as sulphonium ion or sulfanium ion, is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S-Methylmethionine
''S''-Methylmethionine (SMM) is a derivative of methionine with the chemical formula ( CH3)2S+CH2CH2CH(NH3+)CO2−. This cation is a naturally-occurring intermediate in many biosynthetic pathways owing to the sulfonium functional group. It is biosynthesized from L-methionine which is first converted to ''S''-adenosylmethionine. The subsequent conversion, involving replacement of the adenosyl group by a methyl group is catalyzed by the enzyme methionine ''S''-methyltransferase. ''S''-methylmethionine is particularly abundant in plants, being more abundant than methionine. ''S''-Methylmethionine is sometimes referred to as ''vitamin U'', but it is not considered a true vitamin. The term was coined in 1950 by Garnett Cheney for uncharacterized anti-ulcerogenic factors in raw cabbage juice that may help speed healing of peptic ulcers. Biosynthesis and biochemical function ''S''-Methylmethionine arises via the methylation of methionine by ''S''-adenosyl methionine (SAM). The copr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thioether
In organic chemistry, an organic sulfide (British English sulphide) or thioether is an organosulfur functional group with the connectivity as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. A sulfide is similar to an ether except that it contains a sulfur atom in place of the oxygen. The grouping of oxygen and sulfur in the periodic table suggests that the chemical properties of ethers and sulfides are somewhat similar, though the extent to which this is true in practice varies depending on the application. Nomenclature Sulfides are sometimes called thioethers, especially in the old literature. The two organic substituents are indicated by the prefixes. (CH3)2S is called dimethylsulfide. Some sulfides are named by modifying the common name for the corresponding ether. For example, C6H5SCH3 is methyl phenyl sulfide, but is more commonly called thioanisole, since its structure is related to that for anisole, C6H5OCH3. The modern sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylsulfoniopropionate
Dimethylsulfoniopropionate (DMSP), is an organosulfur compound with the formula (CH3)2S+CH2CH2COO−. This zwitterionic metabolite can be found in marine phytoplankton, seaweeds, and some species of terrestrial and aquatic vascular plants. It functions as an osmolyte as well as several other physiological and environmental roles have also been identified. DMSP was first identified in the marine red alga '' Polysiphonia fastigiata''. Biosynthesis In higher plants, DMSP is biosynthesized from ''S''-methylmethionine. Two intermediates in this conversion are dimethylsulfoniumpropylamine and dimethylsulfoniumpropionaldehyde. In algae, however, the biosynthesis starts with the replacement of the amino group in methionine by hydroxide. Degradation DMSP is broken down by marine microbes to form two major volatile sulfur products, each with distinct effects on the environment. One of its breakdown products is methanethiol (CH3SH), which is assimilated by bacteria into protein su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylsulfoniopropionate Structural Formula V1
Dimethylsulfoniopropionate (DMSP), is an organosulfur compound with the formula (CH3)2S+CH2CH2COO−. This zwitterionic metabolite can be found in marine phytoplankton, seaweeds, and some species of terrestrial and aquatic vascular plants. It functions as an osmolyte as well as several other physiological and environmental roles have also been identified. DMSP was first identified in the marine red alga '' Polysiphonia fastigiata''. Biosynthesis In higher plants, DMSP is biosynthesized from ''S''-methylmethionine. Two intermediates in this conversion are dimethylsulfoniumpropylamine and dimethylsulfoniumpropionaldehyde. In algae, however, the biosynthesis starts with the replacement of the amino group in methionine by hydroxide. Degradation DMSP is broken down by marine microbes to form two major volatile sulfur products, each with distinct effects on the environment. One of its breakdown products is methanethiol (CH3SH), which is assimilated by bacteria into protein sulfur. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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