Fact-checked by Grok 2 weeks ago

Thio-

The prefix thio- is a standard term in chemical nomenclature, derived from the Greek word for sulfur (théion), used to indicate the replacement of an oxygen atom with a sulfur atom in molecular structures, particularly in both inorganic oxyanions and organic functional groups.^[1]^[2] In inorganic chemistry, the thio- prefix commonly modifies the names of oxyanions to form thioanions, where sulfur substitutes for one or more oxygen atoms; for instance, sulfate (SO₄²⁻) becomes thiosulfate (S₂O₃²⁻), and cyanate (OCN⁻) becomes thiocyanate (SCN⁻).^[2]^[3] This substitution often alters the compound's reactivity and properties, such as increasing acidity or changing coordination behavior in metal complexes.^[4] In organic chemistry, thio- denotes sulfur analogs of oxygen-containing functionalities, with thiols (R-SH) serving as the sulfur counterparts to alcohols (R-OH), characterized by a sulfhydryl group that imparts distinct odors and roles in biochemistry, such as in cysteine amino acids.^[1] Thioethers (R-S-R'), analogous to ethers (R-O-R'), feature a carbon-sulfur-carbon linkage and are prevalent in natural products like penicillin, while thioketones and thioesters replace the carbonyl oxygen in ketones and esters, respectively, often exhibiting greater reactivity toward nucleophiles.^[1] These thio-compounds play critical roles in synthetic chemistry, pharmaceuticals, and biological processes, including enzyme catalysis and antioxidant defense.^[5]

Definition and Etymology

Meaning and Origin

The "thio-" prefix in chemical nomenclature denotes the replacement of an oxygen atom with a sulfur atom in chemical compounds.^[6] It derives from the Greek word theîon, meaning sulfur.^[6] The prefix was first systematically used in the 19th century as part of efforts to standardize naming for sulfur analogs of oxygen-containing compounds.^[6] Jöns Jacob Berzelius contributed to its early adoption in the early 1800s through his foundational work on systematic chemical nomenclature, which included descriptions of sulfur-substituted species.^[6] A pivotal milestone came in 1832, when Justus von Liebig applied the prefix in his research on thiocyanic acid (HSCN), helping to establish its conventional use for denoting sulfur substitution.^[6] The scope of "thio-" encompasses both organic functional groups and inorganic species involving such oxygen-to-sulfur replacement.^[6] Related prefixes, such as "seleno-" for selenium analogs, follow analogous substitution principles.^[6]

Linguistic Roots

The prefix "thio-" originates from the Ancient Greek word theîon (θεῖον), denoting sulfur, a term that appears in classical literature to describe the element and its compounds. This word, possibly linked to the root for "divine" or "godly" due to sulfur's association with volcanic fumes and lightning, was employed in medical and natural history texts for sulfurous materials with therapeutic or descriptive properties. For instance, the physician Pedanius Dioscorides, in his De Materia Medica (circa 50–70 AD), referenced sulfur (theîon) in mixtures for treating skin conditions like sunburns, highlighting its role as a pungent, yellow substance used in ancient pharmacology.^[7] In classical Greek and Latin usage, theîon and its Latin equivalent sulfur (often translated as "brimstone") referred to naturally occurring deposits of the mineral, particularly those from volcanic regions evoking fire and divine wrath. Pliny the Elder, in his Naturalis Historia (77 AD), describes sulfur's fiery properties, noting its acrid odor in phenomena like thunderbolts, portraying it as integral to ancient mineralogy with astringent and other medical effects. These pre-chemical references emphasized sulfur's physical characteristics—its bright color, combustibility, and medicinal applications—without systematic classification.^[8] The legacy of theîon evolved into the standardized prefix "thio-" in chemical nomenclature during the early 19th century, with Jöns Jacob Berzelius contributing to its formalization through his systematic approach to chemical notation for sulfur-substituted compounds.^[6]

Nomenclature

In Organic Chemistry

In organic chemistry, the prefix "thio-" is employed in substitutive nomenclature to denote the replacement of an oxygen atom by a sulfur atom in various functional groups, as per IUPAC recommendations.^[9] For thiols, which are sulfur analogues of alcohols, the suffix "-thiol" is used instead of "-ol" to name compounds of the general form R-SH, where the parent chain is numbered to give the carbon attached to sulfur the lowest possible number; for example, CH₃CH₂SH is named ethanethiol.^[10] Similarly, for sulfides (thioethers, R-S-R'), the prefix "sulfanyl-" (or traditionally "thio-") replaces "-oxy-" in ether nomenclature, yielding names like (methylsulfanyl)methane for CH₃SCH₃, though simple symmetrical cases retain functional class names such as dimethyl sulfide.^[10] For thioketones and thioaldehydes, featuring the C=S group, the suffixes "-thione" and "-thial" replace "-one" and "-al", respectively; thus, CH₃CH₂CSCH₃ becomes butane-2-thione. When multiple oxygen atoms are replaced by sulfur, multiplicative prefixes such as "dithio-," "trithio-," and so forth are applied systematically, often in the context of functional replacement nomenclature for groups like carboxylic acids or esters (e.g., dithioacetic acid for CH₃CSSH).^[6] Sulfur-containing functions take precedence as the principal characteristic group in naming when they are senior to other functions according to the IUPAC seniority order for classes, where thiols (-SH) rank below alcohols but above hydrocarbons, and thiocarbonyl groups (-C=S) follow ketones; the parent structure is chosen to include the senior sulfur function, with numbering starting from it if applicable. For instance, in a molecule with both a thiol and a ketone, the ketone is the principal function, and the thiol is expressed as a "sulfanyl-" prefix.^[10] Exceptions to the use of "thio-" arise for higher-oxidation-state sulfur compounds. Sulfonium ions (R₃S⁺) are named using the suffix "-ylium" added to the parent hydride, such as trimethylium for (CH₃)₃S⁺, rather than a thio- derivative. Sulfoxides (R₂S=O) employ the prefix "sulfinyl-" or suffix "-sulfoxide," as in (methylsulfinyl)methane for CH₃SOCH₃.^[10] Certain heterocyclic compounds retain traditional names without strict adherence to thio- replacement; for example, thiophene (a five-membered ring with one sulfur atom) is a retained preferred IUPAC name, while its saturated analogue is systematically named thiolane rather than tetrahydrothiophene.^[10]

In Inorganic Chemistry

In inorganic chemistry, the "thio-" prefix denotes the substitution of an oxygen atom by a sulfur atom in parent structures such as oxoacids, oxyanions, and ligands, as per IUPAC recommendations for functional class and substitutive nomenclature.^[11] This usage preserves the charge and skeletal structure of the parent compound while indicating the specific replacement, typically applied to oxygen-containing anions or coordination entities.^[11] For oxyanions derived from oxoacids, the prefix is systematically incorporated to name sulfur-substituted derivatives, as detailed in IUPAC section IR-8.6.^[11] A representative example is the thiosulfate ion (\mathrm{S_2O_3^{2-}}), formed by replacing one oxygen in the sulfate ion (\mathrm{SO_4^{2-}}) with sulfur, named as sulfurothioate or trioxidosulfidosulfate(2−).^[11] Similarly, the thiocyanate ion (SCN^-) is named as sulfidocyanidate(1−) or nitridosulfidocarbonate(1−), reflecting sulfur's role in place of oxygen in the cyanate analog; as a ligand, it is named thiocyanato.^[11] In coordination compounds, the "thio-" prefix features in ligand nomenclature, particularly for ambidentate species where bonding mode must be specified using locants like κS or κN.^[11] For instance, in complexes such as tetra(thiocyanato-κS)zincate(II), the prefix distinguishes sulfur bonding from nitrogen coordination in the thiocyanato ligand, following IUPAC rules in IR-9.2.4.2.^[11] This convention ensures precise description of the coordination geometry and donor atom involvement.^[11] Polyatomic ions also employ "thio-" for sulfur substitutions in phosphate or sulfite frameworks, per substitutive nomenclature in IR-8.6.^[11] Thiophosphate ions, such as \mathrm{PO_3S^{3-}}, result from replacing one oxygen in phosphate (\mathrm{PO_4^{3-}}) with sulfur and are named as trioxidosulfidophosphate(3−).^[11] Another example is the dithionite ion (\mathrm{S_2O_4^{2-}}), designated as bis(dioxidosulfate)(S–S)(2−), highlighting sulfur-oxygen connectivity.^[11]

Chemical Significance

Properties of Thio- Compounds

Thio- compounds, which incorporate sulfur in place of oxygen in analogous oxo- structures, exhibit distinct physical properties largely attributable to sulfur's larger atomic size, lower electronegativity (2.58 vs. oxygen's 3.44), and reduced ability to form strong hydrogen bonds. For instance, thiols (R-SH) display lower boiling points compared to their alcohol counterparts (R-OH) due to weaker intermolecular hydrogen bonding and van der Waals forces; methanethiol boils at 5.8 °C versus methanol's 64 °C, and ethanethiol at 37 °C versus ethanol's 78 °C.^[12] This results in greater volatility, contributing to the characteristic strong, often unpleasant odors of low-molecular-weight thiols, which arise from their high vapor pressures and the human nose's sensitivity to sulfur-containing volatiles.^[13] Additionally, thio- compounds tend to have higher densities owing to sulfur's greater atomic mass; ethanethiol has a density of 0.839 g/mL at 25 °C, compared to ethanol's 0.789 g/mL at 20 °C.^[14] Their solubility profiles favor nonpolar solvents over water, as the weaker polarity of S-H or C-S bonds reduces hydrophilic interactions relative to O-H or C-O analogs. In terms of chemical stability, the larger size of sulfur leads to lower bond dissociation energies in thio- compounds, making them generally less stable than oxo- analogs and more prone to cleavage or oxidation. The C-S single bond energy is approximately 272 kJ/mol, significantly weaker than the C-O bond at 358 kJ/mol, which facilitates reactions involving bond breaking and increases vulnerability to oxidative processes, such as the conversion of thiols to disulfides.^[15] This reduced bond strength stems from poorer orbital overlap between carbon's 2p orbitals and sulfur's larger 3p orbitals, compared to the more effective 2p-2p overlap in C-O bonds./Chemical_Bonding/Fundamentals_of_Chemical_Bonding/Bond_Energies) Spectroscopically, thio- compounds show characteristic features that aid identification. In infrared (IR) spectroscopy, C-S stretches appear as weak to medium absorptions in the 700-600 cm⁻¹ region, while C=S stretches in thiocarbonyl groups are stronger and occur at 1200-1050 cm⁻¹, lower than the 1750-1650 cm⁻¹ for C=O due to sulfur's mass and bonding.^[16] Nuclear magnetic resonance (NMR) of sulfur is challenging; ³³S NMR, with only 0.75% natural abundance and quadrupolar broadening (I=3/2), is rarely employed, though chemical shifts span -600 to +400 ppm when feasible.^[17] Instead, protons attached to sulfur, such as in S-H groups, resonate at 1.5-3.0 ppm in ¹H NMR, often appearing as triplets due to coupling with adjacent methylene groups.

Reactivity Differences from Oxo- Analogs

Thio- compounds often display enhanced reactivity compared to their oxo- analogs due to the larger atomic size and lower electronegativity of sulfur, which result in weaker bonds and greater polarizability. A prominent example is the oxidation sensitivity of thiols, which oxidize more readily to disulfides than alcohols do to the corresponding ethers or other oxidized species. The process follows the half-reaction

$2 \mathrm{RSH} \rightleftharpoons \mathrm{RSSR} + 2 \mathrm{H}^+ + 2 \mathrm{e}^-

and occurs under mild aerobic or oxidative conditions, whereas alcohols typically require stronger oxidants and higher temperatures for comparable transformations.^[18]^[19] This difference arises from the lower oxidation potential of the S-H bond relative to the O-H bond, making thiols susceptible to auto-oxidation in air.^[20] Similarly, thioketones exhibit accelerated hydrolysis rates compared to ketones, attributed to the weaker C=S π-bond (bond energy approximately 570 kJ/mol versus 745 kJ/mol for C=O), which facilitates nucleophilic attack by water. Under aqueous conditions, thioketones revert to ketones more rapidly, limiting their stability in protic media and necessitating anhydrous environments for their handling.^[21]^[22] This heightened reactivity extends to other nucleophilic additions, where the polarized thiocarbonyl group enhances electrophilicity at carbon. In terms of nucleophilicity, thioethers surpass ethers in SN2 reactions owing to sulfur's higher polarizability, which allows better orbital overlap with electrophilic centers despite similar basicities. For instance, dimethyl sulfide reacts faster with methyl iodide than dimethyl ether by factors of up to 10^3 in protic solvents./Thiols_and_Sulfides/Nucleophilicity_of_Sulfur_Compounds) This property stems from sulfur's diffuse electron cloud, enabling more effective stabilization of the transition state. Coordination chemistry further highlights sulfur's distinct behavior: thiolates bind more strongly to soft metal ions than alkoxides, as predicted by the Hard-Soft Acid-Base (HSAB) theory, where thiolates act as soft bases preferring soft acids like Cu(I) or Hg(II). Stability constants for thiolate-metal complexes can exceed those of alkoxide analogs by orders of magnitude for soft metals, influencing selectivity in metalloproteins and synthetic catalysts.^[23]^[24]

Common Examples

Thiols and Sulfides

Thiols, also known as mercaptans, are organic compounds containing the sulfhydryl group (-SH) attached to a carbon atom, with the general formula R-SH. One representative example is ethanethiol (CH_3CH_2SH), a simple alkanethiol widely used as an odorant additive to make odorless gases like natural gas and liquefied petroleum gas detectable by smell due to its strong, garlic-like odor.^[14] Another important thiol is cysteine (HS-CH_2-CH(NH_2)COOH), an amino acid whose thiol group plays a critical role in forming disulfide bonds that stabilize protein tertiary structures.^[25] Sulfides, or thioethers, feature a sulfur atom bridged between two carbon groups (R-S-R'), analogous to ethers but with sulfur replacing oxygen. Dimethyl sulfide ((CH_3)_2S) is a prominent example, produced by the microbial degradation of dimethylsulfoniopropionate in marine algae and phytoplankton, contributing to the characteristic "ocean smell" through its volatile emission.^[26]^[27] Thioether linkages also appear in natural products such as antibiotics; for instance, the thiazolidine ring in penicillin contains a thioether sulfur that is integral to its beta-lactam structure and biological activity. Thiols are commonly synthesized via nucleophilic substitution where hydrosulfide anion (HS^-) attacks primary or unhindered secondary alkyl halides in an S_N2 reaction, yielding R-SH after protonation.^[28] Sulfides can be prepared in a Williamson-like manner starting from alcohols, first converted to thiols (ROH \to RSH), then deprotonated to thiolates (RS^-), which react with alkyl halides (R'X) to form R-S-R'.^[29] In nomenclature, thiols are denoted with the "-thiol" suffix (e.g., ethanethiol), while sulfides use "alkylsulfanyl" prefixes or "dialkyl sulfide" names.

Thioamides and Thioketones

Thioamides represent a class of organic compounds in which the carbonyl oxygen of amides is replaced by sulfur, resulting in the general structure R-C(S)-NR₂. These compounds exhibit enhanced reactivity compared to their oxo-analogs due to the lower bond energy of the C=S linkage, which facilitates nucleophilic addition and other transformations. A prominent example is thiourea, H₂N-C(S)-NH₂, a symmetric thioamide widely utilized as a vulcanization accelerator in the rubber industry, where it promotes efficient sulfur crosslinking to enhance material durability and elasticity.^[30] Thiourea is typically synthesized through the reaction of carbon disulfide with ammonia to form ammonium dithiocarbamate as an intermediate, followed by thermal decomposition to yield the product.^[31] Thioketones, characterized by the R₂C=S functional group, are another key category of thio-carbonyl compounds, analogous to ketones but with sulfur substitution. Unlike stable ketones, most thioketones are highly reactive and prone to dimerization via [2+2] cycloaddition, forming 1,2-dithietanes or other oligomers, which limits their isolation unless steric or electronic stabilization is present. A representative stable thioketone is thiobenzophenone (Ph₂C=S), often prepared by treating benzophenone with phosphorus pentasulfide (P₄S₁₀) in ethanol under reflux conditions, yielding the deep blue product after purification.^[32] This compound's relative stability arises from the bulky phenyl groups hindering dimerization, allowing its use in photochemical and cycloaddition reactions.^[33] The C=S bonds in both thioamides and thioketones display distinct electronic properties, including greater planarity than C=O bonds, due to sulfur's larger size and higher polarizability, which facilitate extended pi-conjugation within the chromophore.^[34] Additionally, the n→π* electronic transitions in thiocarbonyl groups lead to UV absorption maxima shifted to longer wavelengths (typically 350–500 nm) compared to the 270–300 nm range for carbonyls, owing to the lower energy gap from sulfur's higher polarizability and reduced electronegativity.^[35] These spectral shifts are particularly evident in thioketones like thiobenzophenone, which exhibits a deep blue color due to strong absorption in the visible region (around 590 nm).^[35]

Thiosulfates and Other Inorganic Thio- Compounds

Thiosulfates are inorganic oxyanions containing the thiosulfate group, characterized by the formula S₂O₃²⁻, where a central sulfur atom is bonded to three oxygen atoms and a terminal sulfur atom via an S-S single bond, often represented as [O₃S-S]²⁻.^[36] Sodium thiosulfate (Na₂S₂O₃) is a prominent example, commonly encountered as the pentahydrate Na₂S₂O₃·5H₂O.^[37] In photography, sodium thiosulfate serves as a fixing agent, reacting with unexposed silver halides to form a water-soluble complex, thereby stabilizing the developed image.^[38] Thiosulfates can be prepared industrially by reacting sodium sulfite with elemental sulfur in aqueous solution, as in the process where Na₂SO₃ is boiled with sulfur powder to yield Na₂S₂O₃ after filtration and crystallization.^[39] Alternatively, thiosulfuric acid (H₂S₂O₃) forms from sulfur dioxide and sulfur in water, which can then be neutralized to the sodium salt. Thiosulfates exhibit limited stability in acidic conditions, decomposing to sulfur dioxide and elemental sulfur via the reaction S₂O₃²⁻ + 2H⁺ → SO₂ + S + H₂O.^[40] Other notable inorganic thio- compounds include the thiocyanate ion (SCN⁻), which functions as an ambidentate ligand in coordination chemistry, binding to metals through either the nitrogen or sulfur atom depending on the metal's electronic properties and the coordination environment.^[41] Trithionate (S₃O₆²⁻), another polythionate ion, arises during the oxidation of thiosulfate by certain bacteria or chemical oxidants, featuring a linear S₃ chain with terminal SO₃ groups.^[42]

Applications

In Biochemistry

Thio- compounds play critical roles in protein structure and stability within biological systems, particularly through disulfide bridges formed by the oxidation of cysteine residues to cystine. These covalent bonds between sulfur atoms link distant parts of a polypeptide chain, reducing conformational entropy and thereby stabilizing the folded protein structure against denaturation.^[43] Disulfide bridges are especially prevalent in extracellular proteins, such as antibodies and insulin, where they contribute to maintaining functional conformations under physiological conditions.^[44] Cysteine, as a key amino acid containing a thiol group, serves as the precursor for these bridges, enabling redox-dependent structural dynamics in proteins.^[45] Glutathione (GSH), a tripeptide with a central cysteinyl residue, functions as a major cellular antioxidant by scavenging reactive oxygen species and maintaining the redox balance in cells. In its reduced form, GSH donates electrons to neutralize oxidants, becoming oxidized to glutathione disulfide (GSSG), which is then regenerated back to GSH through the action of glutathione reductase using NADPH as a cofactor.^[46] This NADPH-dependent cycle ensures a high GSH/GSSG ratio, protecting thiol groups in proteins from oxidative damage and supporting detoxification pathways.^[47] In metabolic pathways, thio- compounds are integral to one-carbon metabolism via the methionine cycle, where methionine is converted to S-adenosylmethionine (SAM), the primary methyl donor for nucleic acid, protein, and lipid modifications. SAM facilitates essential processes like histone methylation for gene regulation and phospholipid synthesis for membrane integrity, with the cycle recycling homocysteine back to methionine through folate- and B12-dependent remethylation.^[48] Coenzyme A, featuring a terminal thiol group, forms high-energy thioester linkages, as seen in acetyl-CoA, which serves as a central hub for carbohydrate, lipid, and amino acid metabolism, including entry into the citric acid cycle and fatty acid synthesis.^[49] Hydrogen sulfide (H2S), an endogenous gasotransmitter, acts as a signaling molecule in mammalian cells, modulating vasodilation, neuromodulation, and inflammation through protein persulfidation, a post-translational modification of cysteine thiols.^[50] In plant and microbial defense, organosulfur compounds like allicin—derived from garlic alliin via alliinase—exert antimicrobial effects by reacting with microbial thiol-containing enzymes, disrupting essential metabolic functions and inhibiting pathogen growth.^[51]

In Industry

Sodium thiosulfate plays a crucial role in the photographic industry as a fixing agent, where it dissolves unexposed silver halide crystals from film and paper emulsions after development, preventing further image degradation upon light exposure.^[52] This process, known as fixation, relies on the thiosulfate's ability to form soluble silver thiosulfate complexes, allowing the stable retention of the developed silver image.^[53] Historically, ammonium thiosulfate has supplemented sodium thiosulfate in rapid fixers for more efficient processing in modern workflows.^[54] In the rubber and polymer sector, thiourea derivatives serve as secondary accelerators in sulfur vulcanization, enhancing cross-linking efficiency and improving the mechanical properties of elastomers like natural rubber and butyl rubber.^[55] These compounds, such as N,N'-diphenylthiourea, promote faster cure rates at lower temperatures while maintaining scorch safety, making them valuable in tire and hose manufacturing.^[56] Carbon disulfide, another key thio-compound, is essential for viscose rayon production, where it xanthates cellulose to form the soluble viscose solution spun into fibers for textiles and cellophane.^[57] This application consumes a significant portion of global carbon disulfide output, underscoring its industrial scale despite environmental concerns.^[58] Thio-compounds are integral to pharmaceutical manufacturing, exemplified by captopril, the first orally active angiotensin-converting enzyme (ACE) inhibitor, which features a thiol group critical for zinc chelation and enzyme inhibition in hypertension treatment.^[59] The sulfhydryl moiety in captopril's structure (D-3-mercapto-2-methylpropanoyl-L-proline) enables potent antihypertensive effects, influencing the development of thiol-based drugs.^[60] Thioethers appear in antipsychotics like thiothixene, a thioxanthene derivative where the central sulfur atom contributes to its rigid structure and dopamine receptor antagonism for schizophrenia management.^[61] Environmentally, thiosulfates offer sustainable alternatives in mining and water treatment; in gold extraction, ammonium or sodium thiosulfate leaches gold from ores as a non-toxic substitute for cyanide, achieving comparable recovery rates with reduced ecological impact on carbonaceous and refractory deposits.^[62] This method operates under ammoniacal conditions to stabilize the thiosulfate-gold complex, supporting greener heap leaching operations.^[63] In wastewater management, sodium thiosulfate dechlorinates effluents by reducing free chlorine to chloride ions, typically at a dosage of 2-7 parts thiosulfate per part chlorine, ensuring compliance with discharge standards and protecting aquatic ecosystems.^[64]

References

[1]
Organic Molecules - EdTech Books
The sulfur analog of an alcohol is called a thiol (the prefix thio, derived from the Greek, refers to sulfur). Lewis structures of a primary thiol, a ...
[2]
CH150: Chapter 3 - Ions and Ionic Compounds - Chemistry
One last prefix you may find is thio-. It means an oxygen has been replaced with a sulfur within the oxyanion. Cyanate is OCN–, and thiocyanate is SCN ...
[3]
[PDF] CSUS Chemistry 1A Nomenclature Worksheet Dr. Mack Page 1 of 9
There is some regularity in the names of these polyatomic ions. a. Thio- implies replacing oxygen with sulfur: SO4. 2– = sulfate.
[4]
The Chemistry of Oxygen and Sulfur
Examples in this table show how the prefix thio- can be used to indicate compounds in which sulfur replaces an oxygen atom. The thiocyanate (SCN-) ion, for ...
[5]
[PDF] Principles of Chemical Nomenclature - IUPAC
The first version of this book was written in the conviction that although precise and accurate nomenclature is a vital aspect of professional training.
[6]
Burn Care in the Greek and Roman Antiquity - PMC - NIH
Nov 28, 2020 · Dioscorides mixed sulfur together with Carthamus corymbosus to avoid spots of sunburns [12] (bk.3; paragraph 9). He also described how the ...
[7]
https://pmc.ncbi.nlm.nih.gov/articles/PMC7761083/
[8]
So long sulphur | Nature Chemistry
The Greeks called element 16 'theion', which is similar to the prefix 'thio' that we commonly encounter when describing sulfur-containing compounds today.
[9]
Blue Book chapter P-1 - IUPAC nomenclature
2.2 The affixes 'thio', 'seleno', and 'telluro' indicate replacement of an oxygen atom of a characteristic group by another chalcogen atom. Examples: C6H5-COOH
[10]
404 Not Found
Insufficient relevant content. The URL https://iupac.qmul.ac.uk/BlueBook/P63.html returns a "Not Found" error, indicating no accessible content is available for extraction or summarization.
[11]
[PDF] Nomenclature of Inorganic Chemistry | IUPAC
... prefix 'di' to indicate composition. Whatever the pattern of nomenclature ... thio is now reserved for functional replacement nomenclature (see Section ...
[12]
Chemistry of Polythiols and Their Industrial Applications - PMC - NIH
Comparison of the Physical Properties of Thiols and Alcohols. Thiols are analogues of alcohols in which the oxygen atom is replaced by a sulfur atom, and ...
[13]
Analysis of Potent Odour-Active Volatile Thiols in Foods and ... - NIH
Jul 5, 2019 · Certain volatile thiols are some of the most potent odour-active molecules that are found in nature. Thiols play significant roles in the aroma ...
[14]
Ethanethiol | C2H5SH | CID 6343 - PubChem - NIH
Ethyl mercaptan appears as a clear colorless low-boiling liquid (boiling point 97 °F) with an overpowering, garlic-like/skunk-like odor.
[15]
Common Bond Energies (D - Wired Chemist
Common Bond Energies (D. ) and Bond Lengths (r). Hydrogen. Bond, D (kJ/mol), r ... C-O, 358, 143. C=O, 799, 120. C≡O, 1072, 113. C-B, 356. C-S, 272, 182. C=S, 573 ...
[16]
contribution to the infrared spectra of organosulphur compounds1 c ...
C-S Stretching Frequency. The C-S stretching vibration has been assigned to a weak band in the region 700-600 cm-l (14). We have examined the infrared ...
[17]
33S NMR: Recent Advances and Applications - MDPI
The purpose of this review is to present advances and applications of 33 S NMR, which is an underutilized NMR spectroscopy.
[18]
Organic Disulfides and Related Substances. I. Oxidation of Thiols to ...
Catalytic oxidation of thiols to disulfides using iodine and ... One pot conversion of alcohols to disulfides mediated by benzyltriethylammonium ...
[19]
Protein Thiol Redox Signaling in Monocytes and Macrophages - PMC
The reactivity of a protein thiol is largely determined by its pKa, whereby lower pKa and more acidic thiols are more easily oxidized ( ... alcohols, respectively ...
[20]
[PDF] 1) analogous to alcohols, but suffix is -thiol rather than -ol 2) final
thiols are stronger acids than alcohols. 4. thiols are more easily oxidized than alcohols; oxidation takes place at sulfur. Properties of Thiols. Page 9 ...
[21]
Structure elucidation of thioketone analogues of sildenafil detected ...
Under the hydrolytic reaction conditions employed in this study, thioketones hydrolyze to ketones (e.g., thiosildenafil-->sildenafil), making this a valuable ...
[22]
Thioketone - an overview | ScienceDirect Topics
Thioketones are defined as compounds formed by the reaction of ketones with ... α-Thioketones may be accessed by hydrolysis of the corresponding ...
[23]
Unravelling the intricacies of solvents and sulfur sources in colloidal ...
Jul 10, 2024 · Thiols are considered a soft base in the hard and soft acids and bases (HSAB) concept and can form complexes with soft acid metals. The most ...
[24]
Thiolates - an overview | ScienceDirect Topics
Due to the relatively high acidity of thiols in comparison to alcohols, thiolates are more available at neutral pHs than alkoxides.
[25]
L-(+)-Cysteine | C3H7NO2S | CID 5862 - PubChem
In proteins the formation of disulfide bonds between the thiol groups of cysteine plays an important role for tertiary structure and enzymatic activity; ...
[26]
Dimethyl Sulfide | (CH3)2S | CID 1068 - PubChem
Dimethyl sulfide is produced by marine bacteria, marine algae and phytoplanton in oceans via the degradation pathway of dimethylsulfoniopropionate, an ...
[27]
The chemical compounds behind the scent of the sea
Jul 18, 2014 · DMS and hydrogen sulfide aren't the sole contributors to the sea smell though – chemical derivatives of DMS can also have a hand. DMS also has ...
[28]
Reactions of Thiols - Chemistry Steps
So, thiols have lower pKa than alcohols, which is to say that thiols are stronger acids than alcohols. In fact, the acidity of the thiol is almost a million ...
[29]
Preparation of sulfides (video) - Khan Academy
Jan 3, 2013 · How to prepare sulfides from thiols. Sulfides are ... So ethyl phenyl sulfide is the sulfide produced in this analog of the Williamson ether synthesis.
[30]
Thioureas - Accelerators - Vanderbilt Worldwide, Ltd.
Sulfur-bearing accelerators make the sulfur-vulcanization process safer and more efficient. Crosslinking is also achieved by organic peroxides, which may be ...
[31]
[PDF] Synthesis and characterization of thiourea
Thiourea is slightly soluble in cold water, soluble in hot water, and can be recrystal- lized from ethanol Thiourea is a general reagent used in synthetic ...
[32]
http://www.orgsyn.org/demo.aspx?prep=cv4p0927
[33]
Product Class 6: Thioketones - Thieme E-Books
Aliphatic low-molecular-weight thioketones have a tendency to dimerize or oligomerize spontaneously unless there is electronic or steric stabilization in the ...<|control11|><|separator|>
[34]
[PDF] Product Class 1: Thiocarboxylic Acids and Derivatives
lone pair on carbon could overlap with the vacant d-orbital on sulfur, which was contract- ... Thiocarbonyl compounds react with dihalocarbenes to give ...
[35]
Electronic absorption spectra of thiourea derivatives
The long- wavelength low-intensity bands in these derivatives have been assigned to the n→→ * transitions (4) of the thiocarbonyl group. The n→→→ * transition ...
[36]
Thiosulfate Ion
Structural Formula. S2O32-. thiosulfate ion. Molecular Model.
[37]
Thiosulfate ion | O3S2-2 | CID 1084 - PubChem
Molecular Formula. O3S ; Synonyms. THIOSULFATE ION; Thiosulphate; Thiosulfate ion(2-); thiosulfate(2-); Thiosulfate (2-) ; Molecular Weight. 112.13 g/mol.
[38]
Chemistry and the Black and White Photographic Process
The most commonly used fixer, sodium thiosulfate (Na2S2O3), reacts with silver halides to form sodium sulfatoargentate (Na3[Ag(S2O3)2]), a very soluble ...
[39]
Preparation of Sodium Thiosulfate - Alfa Chemistry
Basic Principle. In this experiment, sodium thiosulfate was prepared by co-cooking sodium sulfite and sulfur. Then after filtration, evaporation, concentration ...
[40]
Sodium Thiosulfate - Ricca Chemical Company
Sodium Thiosulfate solutions decompose in acid solution resulting in the evolution of Sulfur Dioxide gas and precipitation of elemental Sulfur.
[41]
Coordination Chemistry of the Cyanate, Thiocyanate, and ...
Thus, the thiocyanate ion, for example, will form either N- or S-bonded complexes depending on the nature of the metal, and this preference may be modified by ...
[42]
PATH OF SULFUR IN SULFIDE AND THIOSULFATE OXIDATION ...
17). Tetra- and trithionate were also formed early in thiosulfate oxidation by T. thioparus extracts. In contrast to the results with T. thiooxidans ...
[43]
Reactivity of disulfide bonds is markedly affected by structure and ...
Dec 12, 2016 · Disulfide bonds play a key role in stabilizing protein structures, with disruption strongly associated with loss of protein function and activity.
[44]
From structure to redox: the diverse functional roles of disulfides and ...
Disulfide bonds have classically been shown to stabilize proteins by maintaining overall structure via intermolecular and intra-domain covalent bonds between ...
[45]
Cysteines and Disulfide Bonds as Structure-Forming Units
Apr 23, 2020 · In this mini-review we present shortly the impact of cysteine and disulfide bonds in the proteasome from different domains of life.
[46]
The antioxidant glutathione - PubMed
GSH can act directly as an antioxidant to protect cells against free radicals and pro-oxidants, and as a cofactor for antioxidant and detoxification enzymes ...
[47]
Glutathione-Related Enzymes and Proteins: A Review - MDPI
Together with glutaredoxins (Grx), GSH acts to reduce disulfide bonds and is, in turn, oxidized to glutathione disulfide (GSSG), which is reduced by NADPH- ...
[48]
Methionine metabolism and methyltransferases in the regulation of ...
Methionine metabolism can be broken into three parts: the methionine cycle, the transsulfuration pathway, and the salvage cycle (Figure 1). Figure 1. Figure 1.
[49]
The Pathophysiological Role of CoA - PMC - PubMed Central
Coenzyme A participates in more than 100 different catabolic and anabolic reactions, including those involved in the metabolism of lipids, carbohydrates, ...
[50]
Signaling Molecules: Hydrogen Sulfide and Polysulfide - PMC - NIH
Significance: Hydrogen sulfide (H2S) has been recognized as a signaling molecule as well as a cytoprotectant. It modulates neurotransmission, regulates vascular ...
[51]
Antibacterial Properties of Organosulfur Compounds of Garlic ...
The organosulfur compounds of garlic exhibit a range of antibacterial properties such as bactericidal, antibiofilm, antitoxin, and anti-quorum sensing activity.
[52]
Chemical Photography - The Chemistry of Art
This process is known as fixing. The photographic film or paper is then treated with a solution of sodium thiosulfate, Na2S2O3, also known as sodium ...Missing: mechanism | Show results with:mechanism
[53]
The chemistry of photography - John Straub's lecture notes
The basic chemistry of exposing and fixing a photographic image is explored. Ingredients: silver nitrate, sodium thiosulfate, tungsten light
[54]
[PDF] Formation of silver sulfide in the photographic image during fixation.
The thiosulfaLe must be removed from processed films and papers when investigating the reaction of thiosulfato with the silver of the image during fixation. ...
[55]
Acceleration by Thiourea and Related Compounds of the ...
Abstract. It has recently been discovered that thiourea and certain of its N-derivatives and chemically related compounds, accelerate the vulcanization of ...
[56]
Amidino Thiourea as a Secondary Accelerator in the Sulphur ...
As a part of our study on the mechanism of vulcanization we investigated a number of thiourea derivatives as secondary accelerators in the sulphur ...
[57]
[PDF] Carbon Disulfide - Development Support Document
Mar 7, 2017 · The most prominent industrial use of CS2 is in the production of viscose rayon fibers; it is also used in the production of carbon tetrachloride ...
[58]
[PDF] Preliminary Study of Carbon Disulfide Discharges from Cellulose ...
WASTEWATER SOURCES At cellulose products manufacturing facilities, the primary sources of wastewater containing CS2 are railcar unloading, storage, viscose ...
[59]
Captopril - an overview | ScienceDirect Topics
Captopril (D-3-mercapto-2-methylpropanoyl-L-proline) is an angiotensin converting enzyme (ACE) inhibitor with a free thiol group used for the treatment of ...
[60]
Angiotensin-converting enzyme inhibitor captopril prevents ... - NIH
The thiol group present on captopril is not only essential to its ability to inhibit Zn2+-dependent ACE, but also enables the drug to block other enzymes with ...
[61]
Thiothixene | C23H29N3O2S2 | CID 941651 - PubChem
A thioxanthine used as an antipsychotic agent. Its effects are similar to the phenothiazine antipsychotics.Missing: thioether | Show results with:thioether
[62]
Review of gold leaching in thiosulfate-based solutions - ScienceDirect
Thiosulfate is a promising, non-toxic alternative to cyanide for gold leaching, with high rates and good performance with carbonaceous and copper-bearing ores. ...
[63]
[PDF] thiosulphate leaching – an alternative to cyanidation in gold ... - SGS
Thiosulphate leaching removes gold without cyanide, is less toxic, and can be more efficient with some ores, and is a lower cost alternative.
[64]
[PDF] The Ins and Outs of Dechlorination | Syndel
The dose required will vary with the pH of the water, but is approximately 2 to 7 parts sodium thiosulphate per one part chlorine. It is important to note that ...