I've always heard that you feed extra Magnesium to make buds stinky. I read recently that Sulfur is the key to dank. post #96
Is there any consensus? Or other teks to increase smell?
My main hypothesis is that if Sulfur increases a certain terpene, it is because the particular terpene molecule contains Sulfur, or uses Sulfur in its metabolic pathway (needed to synthesize it). Or else Sulfur ISN'T involved in terpene production.
It's silly to suggest that plant tissue samples will have the same composition as fertilizer ppm...they are made FROM fertilizer, they are not fertilizer. incidentally, only 4% of the plant's mass comes from fertilizer - the bulk from air and water - so it's even silly to say that plants are made from food...but you get the picture.
here are some threads I came upon:
in French
"(E)-BCP is a natural and powerful anti-inflammatory component that is also found in food items like black pepper, oregano, basil, lime, cinnamon, carrots, and celery." This molecule contains Fluoride, but no Magnesium or Sulfur.
I'll research the following
terpenes (list from greenhouse seeds) when I get a chance:
1. alpha pinene
2.
camphene
3. beta pinene
4. sabinene
5.
Delta 3 carene
6. alpha phellandrene
7. alpha terpinene
8.
limonene
9. 1,8 cineole
10. y terpinene
11. cis
ocimene
12. trans
ocimene
13. alpha terpinolene
14. trans
caryophyllene
15. alpha
humulene
------------------------------------------------------------------------
Some old work I saved on smells; I would check out wiki its more picture friendly:
Organosulfur compounds
From Wikipedia, the free encyclopedia
(Redirected from Organosulfur chemistry)
Jump to: navigation, search
Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odours, but many of the sweetest compounds known are organosulfur derivatives. Nature abounds with organosulfur compounds—sulfur is essential for life. Two of the 20 common amino acids are organosulfur compounds. 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, and it is expected that organosulfur compounds have similarities with carbon-oxygen compounds, which is true to some extent.
A classical chemical test for the detection of sulfur compounds is the Carius halogen method.
Contents
[hide]
• 1 Classes of organosulfur compounds
o 1.1 Thioethers, thioesters, thioacetals
o 1.2 Thiols, disulfides, polysulfides
o 1.3 CS Double bonds
o 1.4 CS triple bonds
o 1.5 Sulfonic acids, esters, amides
o 1.6 Sulfuranes and persulfuranes
• 2 Naturally occurring organosulfur compounds
• 3 Organosulfur compounds in pollution
o 3.1 Organosulfur compounds in fossil fuels
• 4 See also
• 5 External links
• 6 References
[edit] Classes of organosulfur compounds
Organosulfur compounds can be classified according to the sulfur-containing functional groups, which are listing in decreasing order of their occurrence.
[edit] Thioethers, thioesters, thioacetals
Thioethers are characterized by C-S-C bonds. The C-S bond is both longer, because S is larger, and weaker than C-C bonds. Selected bond lengths in sulfur compounds are 183 pm for the S-C single bond in methanethiol and 173 pm in thiophene. The C-S bond dissociation energy for thiomethane is 89 kcal/mol (370 kJ/mol) compared to methane's 100 kcal/mol (420 kJ/mol) and when hydrogen is replaced by a methyl group the energy decreases to 73 kcal/mol (305 kJ/mol).[1]
The single carbon to oxygen bond is shorter than that of the C-C bond. The bond dissociation energies for dimethyl sulfide and dimethyl ether are respectively 73 and 77 kcal/mol (305 and 322 kJ/mol.
Thioethers are typically prepared by alkylation of thiols. They can also be prepared via the Pummerer rearrangement. In one named reaction called the Ferrario reaction phenyl ether is converted to phenoxathiin by action of elemental sulfur and aluminium chloride [2]
Thioacetals, which are useful in umpolung of carbonyl groups, are a special class of thioethers as well as thioesters with general structure R-CO-S-R.
Thiophenes represent a special class of thioethers that are aromatic. The resonance stabilization of thiophene is 29 kcal/mol (121 kJ/mol) compared to 20 kcal/mol (84 kJ/mol) for the oxygen analogue furan. The reason for this difference is the higher electronegativity for oxygen drawing away electrons to itself at the expense of the aromatic ring current. Yet as an aromatic substituent the thio group is less effective as an activating group than the alkoxy group.
[edit] Thiols, disulfides, polysulfides
Thiol group contain the functionality R-SH. Thiols are structurally similar to the alcohol group, but these functionalities are very different in their chemical properties. Thiols are correspondingly more nucleophilic, more acidic, and more readily oxidized. This acidity can differ by 5 pKa units [3].
The difference in electronegativity between sulfur (2.58) and hydrogen (2.20) is small and therefore hydrogen bonding in thiols is not prominent. Aliphatic thiols form monolayers on gold, which are topical in nanotechnology.
Certain aromatic thiols can be accessed through a Herz reaction.
Disulfides R-S-S-R with a covalent sulfur to sulfur bond are important for crosslinking: in biochemistry for the folding and stability of some proteins and in polymer chemistry for the crosslinking of rubber.
Longer sulfur chains are also known, such as in the natural product varacin which contains an unusual pentathiepin ring (5-sulfur chain cyclised onto a benzene ring)
[edit] CS Double bonds
Double bonds of carbon and sulfur are relatively uncommon, because such species often tend to oligomerize or polymerize. Exceptions to this rule include carbon disulfide, carbonyl sulfide, and thiophosgene. Resonance-stabilized C=S bonds are more common, as found in thioamides (see below) and related species.
Thioketones have the general structure RC(=S)R'. These species are quite rare, in contrast to their oxygen analogues. Thioaldehydes are rarer still, reflecting their lack of steric protection. Thioamides, with the formula R1C(=S)N(R2)R3 are more common. They are typically prepared by the reaction of amides with Lawesson's reagent.
Double bonds of carbon and sulfur exist as Sulfonium ylides for instance in the Johnson-Corey-Chaykovsky reaction.
[edit] CS triple bonds
Triple bonds between sulfur and carbon in sulfaalkynes are rare and can be found in Carbon monosulfide (CS) [4] and have been suggested for the compounds F3CCSF3 [5] [6] and F5SCSF3 [7]. The compound HCSOH is also presented as having a formal triple bond [8].
[edit] Sulfonic acids, esters, amides
Sulfonic acids have functionality RS(=O)2OH. They are strong acids that are typically soluble in organic solvents. Sulfonic acids like Trifluoromethanesulfonic acid is a frequently used reagent in organic chemistry. Sulfa drugs are sulfonamides derived from aromatic sulfonation.
[edit] Sulfuranes and persulfuranes
Sulfuranes are relatively specialized functional group that are tetravalent, hypervalent sulfur compounds, with the formula SR4 [9] and likewise persulfuranes are hexavalent SR6. All-carbon persulfuranes have been known for the heavier representatives of the chalcogen group, for instance the compound hexamethylpertellurane (Te(Me)6) was discovered in 1990 [10] by reaction of tetramethyltellurium with xenon difluoride to Te(Me)2)F2 followed by reaction with diethylzinc. The sulfur analogue hexamethylpersulfurane SMe6 has been predicted to be stable [11] but has not been synthesized yet.
The first ever all-carbon persulfurane actually synthesized in a laboratory has two methyl and two biphenyl ligands [12]:
It is prepared from the corresponding sulfurane 1 with xenon difluoride / boron trifluoride in acetonitrile to the sulfuranyl dication 2 followed by reaction with methyllithium in tetrahydrofuran to (a stable) persulfurane 3 as the cis isomer. X-ray diffraction shows C-S bond lengths ranging between 189 and 193 pm (longer than the standard bond length) with the central sulfur atom in a distorted octahedral molecular geometry.
In silico experiments suggest that these bonds are very polar with the negative charges residing on carbon.
[edit] Naturally occurring organosulfur compounds
Not all organosulfur compounds are foul-smelling pollutants. Compounds like allicin and ajoene are responsible for the odor of garlic, and lenthionine contributes to the flavor of shiitake mushrooms. Many of these natural products also have important medicinal properties such as preventing platelet aggregation or fighting cancer.
[edit] Organosulfur compounds in pollution
Most organic sulfur compounds in the environment are naturally occurring, as a consequence of the fact that sulfur is essential for life and two amino acids contain this element.
Some organosulfur compounds in the environment, are generated as minor by-products of industrial processes such as the manufacture of plastics and tires.
Selected smell-producing processes are organosulfur compounds produced by the coking of coal designed to drive out sulfurus compounds and other volatile impurities in order to produce 'clean carbon' (coke), which is primarily used for steel production.
[edit] Organosulfur compounds in fossil fuels
Odours occur as well in chemical processing of coal or crude oil into precursor chemicals (feedstocks) for downstream industrial uses (e.g. plastics or pharmaceutical production) and the ubiquitous needs of petroleum distillation for (gasolines, diesel, and other grades of fuel oils production.
Organosulfur compounds might be understood as smelly contaminants that need to be removed from natural gas before commercial uses, from exhaust stacks and exhaust vents before discharge. In this latter context, organosulfur compounds may be said to account for the pollutants in sulfurous acid rain, or equivalently, said to be pollutants within most common fossil fuels, especially coal.
[edit] See also
CH
He
CLi
CBe
CB
CC
CN
CO
CF
Ne
CNa
CMg
CAl
CSi
CP
CS CCl
CAr
CK
CCa
CSc
CTi
CV
CCr
CMn
CFe
CCo
CNi
CCu
CZn
CGa
CGe
CAs
CSe
CBr
CKr
CRb
CSr
CY
CZr
CNb
CMo
CTc
CRu
CRh
CPd
CAg
CCd
CIn
CSn
CSb
CTe
CI
CXe
CCs
CBa
CHf
CTa
CW
CRe
COs
CIr
CPt
CAu
CHg
CTl
CPb
CBi
CPo CAt Rn
Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Uuq Uup Uuh Uus Uuo
↓
La CCe Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa CU
Np Pu Am Cm Bk Cf Es Fm Md No Lr
Chemical bonds to carbon
Core organic chemistry Many uses in chemistry.
Academic research, but no widespread use Bond unknown / not assessed.
[edit] External links
• Organosulfur chemistry at
http://users.ox.ac.uk Link
[edit] References
1. ^ Handbook of Chemistry and Physics, 81st Edition CRC Press ISBN 0-8493-0481-4
2. ^ Organic Syntheses, Coll. Vol. 2, p.485 (1943); Vol. 18, p.64 (1938). Article link
3. ^ Organosulfur chemistry. reviews of current research JANSSEN, M.J. Interscience, New York,(1967)
4. ^ Moltzen, E. K.; Klabunde, K. J.; Senning, A. (1988). "Carbon monosulfide: a review". Chemical Reviews 88: 391. doi:10.1021/cr00084a003. edit
5. ^ Pötter, B.; Seppelt, K. (1984). "Trifluoroethylidynesulfur Trifluoride, F3CCSF3". Angewandte Chemie International Edition in English 23: 150. doi:10.1002/anie.198401501. edit
6. ^ Buschmann, J.; Damerius, R.; Gerhardt, R.; Lentz, D.; Luger, P.; Marschall, R.; Preugschat, D.; Seppelt, K. et al. (1992). "(Trifluoroethylidyne)sulfur trifluoride, F3CC.tplbond.SF3: two solid-state structures and reactivity as a carbene". Journal of the American Chemical Society 114: 9465. doi:10.1021/ja00050a027. edit
7. ^ Gerhardt, R.; Gerlbig, T.; Buschamann, J. �R.; Luger, P.; Seppelt, K. (1988). "The SF5-Unit as Steric Protecting Group; Synthesis and Structure of F5SCSF3". Angewandte Chemie International Edition in English 27: 1534. doi:10.1002/anie.198815341. edit
8. ^ Schreiner, P.; Reisenauer, H.; Romanski, J.; Mloston, G. (2009). "A formal carbon-sulfur triple bond: H-Ctriple bondS-O-H.". Angewandte Chemie (International ed. in English) 48 (43): 8133–8136. doi:10.1002/anie.200903969. PMID 19768827. edit
9. ^ For an example bis[2,2,2-trifluoro-1-phenyl-1-(trifluoromethyl) ethoxy] diphenyl sulfurane Organic Syntheses, Coll. Vol. 6, p.163 (1988); Vol. 57, p.22 (1977) Link.
10. ^ Synthesis and characterization of hexamethyltellurium(VI) Latif Ahmed, John A. Morrison J. Am. Chem. Soc.; 1990; 112(20); 7411-7413. Abstract
11. ^ The S6 Point Group Conformers of the Hexamethylchalcogens: Me6S, Me6Se, Me6Te Fowler, J. E.; Schaefer, H. F., III; Raymond, K. N. Inorg. Chem.; (Article); 1996; 35(2); 279-281. doi: 10.1021/ic940240d
12. ^ Isolation and Molecular Structure of the Organo-persulfuranes [12-S-6(C6)] Sato, S.; Matsunaga, K.; Horn, E.; Furukawa, N.; Nabeshima, T. J. Am. Chem. Soc.; (Communication); 2006; 128(21); 6778-6779. doi:10.1021/ja060497y
Retrieved from "http://en.wikipedia.org/wiki/Organosulfur_compounds"
Categories: Organosulfur compounds | Soil chemistry
Thiol
From Wikipedia, the free encyclopedia
Jump to: navigation, search
General chemical structure of the thiol functional group
In organic chemistry, a thiol is an organosulfur compound that contains a sulfur-hydrogen bond (S-H). Thiols are the sulfur analogue of an alcohol. The SH functional group is referred to as either a thiol group or a sulfhydryl group. Thiols are often referred to as mercaptans.[1][2]
Contents
[hide]
• 1 Structure and bonding
• 2 Nomenclature
• 3 Physical properties
o 3.1 Odour
o 3.2 Boiling points and solubility
• 4 Characterization
• 5 Preparation
o 5.1 Laboratory methods
• 6 Reactions
o 6.1 S-alkylation
o 6.2 Acidity
o 6.3 Redox
o 6.4 Metal ion complexation
• 7 Biological importance
o 7.1 Cysteine and cystine
o 7.2 Cofactors
• 8 Examples of thiols
• 9 See also
• 10 References
• 11 External links
[edit] Structure and bonding
Thiols and alcohols have similar molecular structure. The major difference is the size of the chalcogenide, C-S bond lengths being around 180 picometers in length. The C-S-H angles approach 90°. In the solid or molten liquids, the hydrogen-bonding between individual thiol groups is weak, the main cohesive force being van der Waals interactions between the highly polarizable divalent sulfur centers.
Due to the small electronegativity difference between sulfur and hydrogen, an S-H bond is less polar than the hydroxyl group. Thiols have a lower dipole moment relative to the corresponding alcohol.
[edit] Nomenclature
Several ways of naming the alkylthiols:
• The preferred method (used by the IUPAC) is to add the suffix -thiol to the name of the alkane. The method is nearly identical to naming an alcohol. Example: CH3SH would be methanethiol.
• An older method, the word mercaptan replaces alcohol in the name of the equivalent alcohol compound. Example: CH3SH would be methyl mercaptan, just as CH3OH is called methyl alcohol.
• As a prefix, the terms sulfanyl or mercapto are used. Example: mercaptopurine.
[edit] Physical properties
[edit] Odour
Many thiols have strong odours resembling that of garlic. The odours of thiols are often strong and repulsive, particularly for those of low molecular weight. Skunk spray is composed mainly of low molecular weight thiol compounds.[3][4] These compounds are detectable by the human nose at concentrations of only 10 parts per billion.[5]
Thiols are also responsible for a class of wine faults caused by an unintended reaction between sulfur and yeast and the "skunky" odour of beer that has been exposed to ultraviolet light.
However, not all thiols have unpleasant odours. For example, grapefruit mercaptan, a monoterpenoid thiol, is responsible for the characteristic scent of grapefruit. This effect is present only at low concentrations. The pure mercaptan has an unpleasant odour.
Natural gas distributors began adding thiols, originally ethanethiol, to natural gas, which is naturally odourless, after the deadly 1937 New London School explosion in New London, Texas. Most gas odourants utilized currently contain mixtures of mercaptans and sulfides, with t-butyl mercaptan as the main odour constituent. In situations where thiols are used in commercial industry, such as liquid petroleum gas tankers and bulk handling systems, the use of an oxidizing catalyst is used to destroy the odour. A copper-based oxidation catalyst neutralizes the volatile thiols and transforms them into inert products.
[edit] Boiling points and solubility
Thiols show little association by hydrogen bonding, with both water molecules and among themselves. Hence, they have lower boiling points and are less soluble in water and other polar solvents than alcohols of similar molecular weight. Thiols and thioethers have similar solubility characteristics and boiling points.
[edit] Characterization
Volatile thiols are easily and almost unerringly detected by their distinctive odor. S-specific analyzers for gas chromatographs are useful. Spectroscopic indicators are the D2O-exchangeable SH signal in the 1H NMR spectrum (S has no useful "NMR isotopes"). The νSH band appears near 2400 cm−1 in the IR spectrum.[1] In a colorimetric test, thiols react with nitroprusside.
[edit] Preparation
In industry, thiols are prepared mainly by the reaction of hydrogen sulfide with the related alcohol. This method is employed for the industrial synthesis of methanethiol and ethanethiol:
CH3OH + H2S → CH3SH + H2O
Such reactions are conducted in the presence of acidic catalysts. The other principal route to thiols involves the addition of hydrogen sulfide to alkenes. Such reactions are usually conducted in the presence of a metal catalyst.[6]
[edit] Laboratory methods
Many methods are useful for the synthesis of thiols on the laboratory scale. The direct reaction of a halogenoalkane with sodium hydrosulfide is generally inefficient owing to the competing formation of thioethers:
CH3CH2Br + NaSH → CH3CH2SH + NaBr
CH3CH2Br + CH3CH2SH → (CH3CH2)2S + HBr
Instead, alkyl halides are converted to thiols via a S-alkylation of thiourea. This multistep, one-pot process proceeds via the intermediacy of the isothiouronium salt, which is hydrolyzed in a separate step:[7]
CH3CH2Br + SC(NH2)2 → [CH3CH2SC(NH2)2]Br
[CH3CH2SC(NH2)2]Br + NaOH → (CH3CH2SH + OC(NH2)2 + NaBr
The thiourea route works well with primary halides, especially activated ones. Secondary and tertiary thiols are less easily prepared. Secondary thiols can be prepared from the ketone via the corresponding dithioketals.[8]
Organolithium compounds and Grignard reagents react with sulfur to give the thiolates, which are readily hydrolyzed:[9]
RLi + S → RSLi
RSLi + HCl → RSH + LiCl
Phenols can be converted to the thiophenols via rearrangement of their O-aryl dialkylthiocarbamates.[10]
Many thiols are prepared by reductive dealkylation of thioethers, especially benzyl derivatives and thioacetals.[11]
[edit] Reactions
Akin to the chemistry of alcohols, thiols form thioethers, thioacetals and thioesters, which are analogous to ethers, acetals, and esters. Thiols and alcohols are also very different in their reactivity, thiols being easily oxidized and thiolates being highly potent nucleophiles.
[edit] S-alkylation
Thiols, or more particularly their conjugate bases, are readily alkylated to give thioethers:
RSH + R'Br + base → RSR' + [Hbase]Br
[edit] Acidity
Relative to the alcohols, thiols are fairly acidic. Butylthiol has a pKa's of 10.5 vs 15 for butanol. Thiophenol has a pKa's of 6 vs 10 for phenol. Thus, thiolates are obtained from thiols by treatment with alkali hydroxides.
Synthesis of thiophenolate from thiophenol
[edit] Redox
Thiols, especially in the presence of base, are readily oxidized by reagents such as iodine to give an organic disulfide (R-S-S-R).
2 R-SH + Br2 → R-S-S-R + 2 HBr
Oxidation by more powerful reagents such as sodium hypochlorite or
hydrogen peroxide yields sulfonic acids (RSO3H).
R-SH + 3H2O2 → RSO3H + 3H2O
Thiols participate in thiol-disulfide exchange:
RS-SR + 2 R'SH → 2 RSH + R'S-SR'
This reaction is especially important in nature.
[edit] Metal ion complexation
Thiolates, the conjugate bases derived from thiols, form strong complexes with many metal ions, especially those classified as soft. The term mercaptan is derived from the Latin mercurium captans (capturing mercury)[12] because the thiolate group bonds so strongly with mercury compounds. The stability of metal thiolates parallels that of the corresponding sulfide minerals.
[edit] Biological importance
[edit] Cysteine and cystine
As the functional group of the amino acid cysteine, the thiol group plays an important role in biology. When the thiol groups of two cysteine residues (as in monomers or constituent units) are brought near each other in the course of protein folding, an oxidation reaction can generate a cystine unit with a disulfide bond (-S-S-). Disulfide bonds can contribute to a protein's tertiary structure if the cysteines are part of the same peptide chain, or contribute to the quaternary structure of multi-unit proteins by forming fairly strong covalent bonds between different peptide chains. A physical manifestation of cysteine-cystine equilibrium is provided by hair straightening technologies.
Sulfhydryl groups in the active site of an enzyme can form noncovalent bonds with the enzyme's substrate as well, contributing to catalytic activity. Active site cysteine residues are the functional unit in cysteine proteases. Cysteine residues may also react with heavy metal ions (Pb2+, Hg2+, Ag2) because of the high affinity between the soft sulfide and the soft metal (see hard and soft acids and bases). This can deform and inactivate the protein, and is one mechanism of heavy metal poisoning.
[edit] Cofactors
Many cofactors (non-protein-based helper molecules), feature thiols. The biosynthesis and degradation of fatty acids and related long-chain hydrocarbons is conducted on a scaffold that anchors the growing chain through a thioester derived from the thiol Coenzyme A. The biosynthesis of methane, the principal hydrocarbon on earth, arises from the reaction mediated by coenzyme M, 2-mercaptoethyl sulfonic acid.
[edit] Examples of thiols
• Methanethiol - CH3SH [m-mercaptan]
• Ethanethiol - C2H5SH [e- mercaptan]
• 1-Propanethiol - C3H7SH [n-P mercaptan]
• 2-Propanethiol - CH3CH(SH)CH3 [2C3 mercaptan]
• Butanethiol - C4H9SH [n-butyl mercaptan]
• tert-Butyl mercaptan - C(CH3)3SH [t-butyl mercaptan]
• Pentanethiols - C5H11SH [pentyl mercaptan] • Coenzyme A
• Glutathione
• Cysteine
• 2-Mercaptoethanol
• Dithiothreitol/dithioerythritol (an epimeric pair)
• 2-Mercaptoindole
• transglutaminase
[edit] See also
• Doctor sweetening process
• Thiol-disulfide exchange
[edit] References
1. ^ a b Patai, Saul “The chemistry of the thiol group” Saul Patai, Ed. Wiley, London, 1974. ISBN 0471669490.
2. ^ R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN 0 471 95512 4.
3. ^ Wood W. F., Sollers B. G., Dragoo G. A., Dragoo J. W. (2002). "Volatile Components in Defensive Spray of the Hooded Skunk, Mephitis macroura". Journal of Chemical Ecology 28 (9): 1865. doi:10.1023/A:1020573404341.
4. ^ William F. Wood. "Chemistry of Skunk Spray". Dept. of Chemistry, Humboldt State University. . Retrieved January 2, 2008.
5. ^ Aldrich, T.B. (1896). "A chemical study of the secretion of the anal glands of Mephitis mephitica (common skunk), with remarks on the physiological properties of this secretion.". J. Exp. Med. 1 (2): 323–340. doi:10.1084/jem.1.2.323. PMID 19866801. PMC 2117909.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2117909/pdf/323.pdf.
6. ^ Kathrin-Maria Roy “Thiols and Organic Sulfides” in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH Verlag, Weinheim. doi:10.1002/14356007.a26_767
7. ^ Speziale, A. J. (1963), "Ethanedithiol", Org. Synth.,
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0401; Coll. Vol. 4: 401.
8. ^ S. R. Wilson, G. M. Georgiadis (1990), "Mecaptans from Thioketals: Cyclododecyl Mercaptan", Org. Synth.,
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv7p0124; Coll. Vol. 7: 124.
9. ^ E. Jones and I. M. Moodie (1990), "2-Thiophenthiol", Org. Synth.,
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0979; Coll. Vol. 6: 979.
10. ^ Melvin S. Newman and Frederick W. Hetzel (1990), "Thiophenols from Phenols: 2-Naphthalenethiol", Org. Synth.,
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0824; Coll. Vol. 6: 824.
11. ^ Ernest L. Eliel, Joseph E. Lynch, Fumitaka Kume, and Stephen V. Frye (1993), "Chiral 1,3-oxathiane from (+)-Pulegone: Hexahydro-4,4,7-trimethyl-4H-1,3-benzoxathiin", Org. Synth.,
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv8p0302; Coll. Vol. 8: 302
12. ^ Oxford American Dictionaries (Mac OS X Leopard).
[edit] External links
• Applications, Properties, and Synthesis of w-Functionalized n-Alkanethiols and Disulfides — the Building Blocks of Self-Assembled Monolayers by D. Witt, R. Klajn, P. Barski, B.A. Grzybowski at Northwestern University.
• Mercaptan, by The Columbia Electronic Encyclopedia.
• What is Mercaptan?, by Columbia Gas of Pennsylvania and Maryland.
• What Is the Worst Smelling Chemical?, by About Chemistry.
[hide]
v • d • e
Functional groups
Alcohol • Aldehyde • Alkane • Alkene • Alkyne • Amide • Amine • Azo compound • Benzene derivative • Carboxylic acid •
Cyanate • Disulfide • Ester • Ether • Haloalkane • Hydrazone • Imine • Isocyanide • Isocyanate • Ketone • Organophosphorus •
Oxime • Nitrile • Nitro compound • Nitroso compound • Peroxide • Phosphonous and Phosphonic acid •Pyridine derivative •
Sulfone • Sulfonic acid • Sulfoxide • Thioester • Thioether • Thiol
Retrieved from "http://en.wikipedia.org/wiki/Thiol"
Categories: Thiols | Functional groups | Organosulfur compounds | Organic compounds
Sesquiterpene
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Sesquiterpenes are a class of
terpenes that consist of three isoprene units and have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be acyclic or contain rings, including many unique combinations. Biochemical modifications such as oxidation or rearrangement produce the related sesquiterpenoids.
Sesquiterpenes are found naturally in plants and insects, as semiochemicals, e.g. defensive agents or pheromones.
Contents
[hide]
• 1 Acyclic
• 2 Monocyclic
• 3 Bicyclic
• 4 Tricylic
• 5 External links
[edit] Acyclic
When geranyl pyrophosphate reacts with isopentenyl pyrophosphate, the result is the 15-carbon farnesyl pyrophosphate, which is an intermediate in the biosynthesis of sesquiterpenes such as farnesene. Oxidation can then provide sesquiterpenoids such as farnesol.
Farnesyl pyrophosphate
[edit] Monocyclic
With the increased chain length and additional double bond, the number of possible ways that cyclization can occur is also increased, and there exists a wide variety of cyclic sesquiterpenes. In addition to common six-membered ring systems such as is found in zingiberene, a constituent of the oil from ginger, cyclization of one end of the chain to the other end can lead to macrocyclic rings such as
humulene.
[edit] Bicyclic
δ-Cadinene, a sesquiterpene
In addition to common six-membered rings such as in the cadinenes, one classic bicyclic sesquiterpene is
caryophyllene, from the oil of cloves, which has a nine-membered ring and cyclobutane ring. Additional unsaturation provides aromatic bicyclic sesquiterpenoids such as vetivazulene and guaiazulene.
[edit] Tricylic
With the addition of a third ring, the possible structures become increasingly varied. Examples include longifolene, copaene and the alcohol patchoulol.
[edit] External links
• MeSH Sesquiterpenes
Retrieved from "http://en.wikipedia.org/wiki/Sesquiterpene"
Categories: Sesquiterpenes
Succinic acid
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Succinic acid
IUPAC name[hide]
Butanedioic acid
Other names[hide]
ethane-1,2-dicarboxylic acid
Identifiers
CAS number
110-15-6
ChemSpider
1078
SMILES
[show]
Properties
Molecular formula
C4H6O4
Molar mass
118.09 g/mol
Density
1.56 g/cm³
Melting point
185–187 °C
Boiling point
235 °C, 508 K, 455 °F
Solubility in 2-propanol, ethanol
2-propanol 0.32 M, ethanol 0.4 M [1]
Acidity (pKa)
pKa1=4.2
pKa2=5.6
Related compounds
Other anions
succinate
Related carboxylic acids
propionic acid
malonic acid
butyric acid
crotonic acid
malic acid
tartaric acid
fumaric acid
diglycolic acid
pentanoic acid
glutaric acid
Related compounds butanol
butyraldehyde
crotonaldehyde
sodium succinate
(what is this?) (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
Succinic acid (pronounced /səkˈsɪnɨk/; IUPAC systematic name: butanedioic acid; historically known as spirit of amber) is a dicarboxylic acid. Succinate plays a biochemical role in the citric acid cycle. The name derives from Latin succinum, meaning amber, from which the acid may be obtained.
The carboxylate anion is called succinate and esters of succinic acid are called alkyl succinates.
Contents
[hide]
• 1 Physical properties
• 2 Biochemical role
• 3 History
• 4 Safety
• 5 Reactions
• 6 Fermentation
• 7 Interactive pathway map
• 8 References
• 9 See also
• 10 External links
[edit] Physical properties
At room temperature, pure succinic acid is a solid that forms colorless, odorless crystals. It has a melting point of 185 °C and a boiling point of 235 °C. It is a diprotic acid.
[edit] Biochemical role
Succinate is a component of the citric acid cycle and is capable of donating electrons to the electron transport chain by the reaction:
succinate + FAD → fumarate + FADH2.
This is catalysed by the enzyme succinate dehydrogenase (or complex II of the mitochondrial ETC). The complex is a 4 subunit membrane-bound lipoprotein which couples the oxidation of succinate to the reduction of ubiquinone. Intermediate electron carriers are FAD and three Fe2S2 clusters part of subunit B.
[edit] History
Spirit of amber was procured from amber by pulverising and distilling it using a sand bath. It was chiefly used externally for rheumatic aches and pains, and internally in inveterate gleets.
[edit] Safety
The acid is combustible and corrosive, capable of causing burns.
In nutraceutical form as a food additive and dietary supplement, is safe and approved by the U.S. Food and Drug Administration.[2] As an excipient in pharmaceutical products it is used to control acidity[3] and, more rarely, in effervescent tablets.[4]
[edit] Reactions
Succinic acid can be converted to fumaric acid by oxidation. The diethyl ester is a substrate in the Stobbe condensation.
[edit] Fermentation
See also: Acids in wine
Succinic acid is created as a byproduct of the fermentation of sugar. It lends to fermented beverages such as wine and beer a common taste that is a combination of saltiness, bitterness and acidity.[5]
[edit] Interactive pathway map
Click on genes, proteins and metabolites below to visit Gene Wiki pages and related Wikipedia articles. The pathway can be edited at WikiPathways.
[[File:
