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Section: Academic career. Chan King-ming earned his Bachelor of Science and Master of Philosophy degrees at the Chinese University of Hong Kong, and his doctoral degree from Memorial University of Newfoundland in St. John's, Newfoundland, Canada. He is now director of the Environmental Science Program at the Chinese Un... | Wikipedia - Chan King-ming - Academic career | 178 | 1,014 | null |
Section: Political career. Chan is a founding member of the Democratic Party. He was elected as chairman of the New Territories East Branch in 1999, and later became the party's minister of organization affairs and central committee member. He ran for the chairmanship election in 2004 but lost to Lee Wing-tat. He was t... | Wikipedia - Chan King-ming - Political career | 269 | 1,416 | null |
Section: Education and career. Chayen earned her first degree in pharmacy at the Hebrew University of Jerusalem. During her undergraduate studies, she visited the Kennedy Institute of Rheumatology to learn histochemistry. She subsequently pursued MSc and PhD research at the Kennedy Institute. In 1983, Chayen submitted ... | Wikipedia - Naomi Chayen - Education and career | 176 | 955 | null |
Section: Research. Chayen is best known for her invention of novel protein crystallization methods. In 1990, she first published a method of suspending droplets of protein solution and precipitant solutions in low-density paraffin oil to prevent evaporation during the microbatch crystallization process. The microbatch ... | Wikipedia - Naomi Chayen - Research | 265 | 1,198 | null |
Section: Biography. Chetsanga was born in Murewa, Zimbabwe on 22 August 1935, and was baptised in 1948. In his youth, he was educated at Nhowe Mission, and went on to study at University of California, Berkeley where he received his BSc in 1965. Chetsanga also studied for a period at Pepperdine University. In 1969, he ... | Wikipedia - Christopher Chetsanga - Biography | 225 | 1,154 | null |
Section: Select publications. C. J. Chetsanga; V. Boyd; L. Peterson; K. Rushlow (1 January 1975). "Single-stranded regions in DNA of old mice" (PDF). Nature. 253 (5487): 130–131. doi:10.1038/253130A0. ISSN 1476-4687. PMID 1110761. Wikidata Q59071826. C. J. Chetsanga; Tomas Lindahl (10 August 1979). "Release of 7-methyl... | Wikipedia - Christopher Chetsanga - Select publications | 341 | 908 | null |
Section: Researches. Choi researched jasmonates, which are believed to participate in signal transduction processes between external stresses, such as wounding, pathogenic attack, or cell response by activating the defense genes. He discovered a new enzyme, (EC2.1.1.141) jasmonate carboxyl methyltransferase (JMT), whic... | Wikipedia - Choi Yang-do - Researches | 229 | 1,085 | null |
Section: Awards. For his scientific achievements Choi received the New Technology Development Award from the Ministry of Science & Technology (1992), the Special Award from Korean Society for Molecular & Cell Biology from the Korean Society of Molecular and Cellular Biology (1999), the 11th Sangrok Agriculture & Life S... | Wikipedia - Choi Yang-do - Awards | 157 | 833 | null |
Article: Lassar Cohn. Lassar Cohn, Lassar-Cohn or Ernst Lassar Cohn (6 September 1858 – 9 October 1922) was a Prussian chemist and professor at the University of Königsberg who wrote several influential textbooks on organic analysis including methods for the analysis of urine. Cohn was born in the Jewish family of Jaco... | Wikipedia - Lassar Cohn - Summary | 221 | 1,018 | null |
Section: Career. In 1966, Cronin joined the faculty at Arizona State University (ASU) as a professor of biochemistry. At ASU, he became involved in the emerging field of exobiology, focusing on the study of organic materials in extraterrestrial environments. His work at the ASU Center for Meteorite Studies, particularl... | Wikipedia - John Read Cronin - Career | 318 | 1,584 | null |
Section: Research contributions > Organic compounds in meteorites. Cronin's extensive analysis of carbonaceous chondrite meteorites revealed a rich diversity of organic molecules, including amino acids, hydrocarbons, and nucleobases. His research demonstrated that these meteorites contain complex organic compounds that... | Wikipedia - John Read Cronin - Research contributions > Organic compounds in meteorites | 157 | 625 | null |
Section: Research contributions > Chirality and enantiomeric excess. Cronin's research on the chirality of meteoritic amino acids provided evidence of non-racemic mixtures, suggesting a potential extraterrestrial source of chiral asymmetry. This finding has implications for the development of homochirality in biologica... | Wikipedia - John Read Cronin - Research contributions > Chirality and enantiomeric excess | 164 | 572 | null |
Section: Research contributions > Isotopic composition of organic molecules. Cronin conducted isotopic analyses of meteoritic organic compounds, revealing distinct isotopic compositions that supported their non-terrestrial origin. This work provided crucial insights into the extraterrestrial sources of prebiotic molecu... | Wikipedia - John Read Cronin - Research contributions > Isotopic composition of organic molecules | 161 | 631 | null |
Section: Research contributions > Additional selected publications. Cronin, John R.; Chang, Sherwood (1993). "Organic Matter in Meteorites: Molecular and Isotopic Analyses of the Murchison Meteorite". The Chemistry of Life's Origins. pp. 209–258. doi:10.1007/978-94-011-1936-8_9. ISBN 978-94-010-4856-9. Cronin, John R.;... | Wikipedia - John Read Cronin - Research contributions > Additional selected publications | 338 | 955 | null |
Section: Biography. Filipowicz studied at the Faculty of Medicine of the Medical University of Lodz. He received his PhD and habilitation at the Institute of Biochemistry and Biophysics of the Polish Academy of Sciences (PAS) in Warsaw. This was followed by the post-doctoral studies at the New York University Medical S... | Wikipedia - Witold Filipowicz - Biography | 163 | 774 | null |
Section: Selected awards and honors. The Lifetime Achievement in Science Award of the RNA Society (2011). Gutenberg Chair Award (Chaire Gutenberg) 2013, Strasbourg. Member of European Molecular Biology Organization (EMBO) (since 1994). Member of Academia Europaea (since 2005); Chair of the Section of Biochemistry and M... | Wikipedia - Witold Filipowicz - Selected awards and honors | 217 | 1,001 | null |
Section: Selected publications. Filipowicz, W.; Furuichi, Y.; Sierra, J.M.; Muthukrishnan, S.; Shatkin, A.J.; Ochoa, S. (1976). "A protein binding the methylated 5'-terminal sequence, m7GpppN, of eukaryotic messenger RNA". Proceedings of the National Academy of Sciences. 73 (5): 1559–1563. doi:10.1073/pnas.73.5.1559. I... | Wikipedia - Witold Filipowicz - Selected publications | 341 | 831 | null |
Goodall, GJ; Filipowicz, W. (1989). "The AU-rich sequences present in the introns of plant nuclear pre-mRNAs are required for splicing". Cell. 58 (3): 473–483. doi:10.1016/0092-8674(89)90428-5. PMID 2758463. Kiss, T.; Filipowicz, W. (1995). "Exonucleolytic processing of small nucleolar RNAs from pre-mRNA introns". Gene... | Wikipedia - Witold Filipowicz - Selected publications | 338 | 860 | null |
PMID 1826860. Zhang, H.; Kolb, FA; Jaskiewicz, L.; Westhof, E.; Filipowicz, W. (2004). "Single Processing Center Models for Human Dicer and Bacterial RNase III". Cell. 118 (1): 57–68. doi:10.1016/j.cell.2004.06.017. PMID 15242644. Pillai, RS; Bhattacharyya, SN; Artus, CG; Zoller, T.; Cougot, N.; Basyuk, E.; Bertrand, E... | Wikipedia - Witold Filipowicz - Selected publications | 302 | 759 | null |
doi:10.1016/j.cell.2006.04.031. PMID 16777601. Mathys, H.; Basquin, J.; Ozgur, S.; Czarnocki-Cieciura, M.; Bonneau, F.; Aartse, A.; Dziembowski, A.; Nowotny, M.; Conti, E.; Filipowicz, W. (2014). "Structural and biochemical insights to the role of the CCR4-NOT complex and DDX6 ATPase in microRNA repression". Molecular ... | Wikipedia - Witold Filipowicz - Selected publications | 334 | 779 | null |
Section: Career. After his graduation Gamborg joined the Prairie Regional Laboratory (PRL) (now Plant Biotechnology Institute) of the National Research Council of Canada in Saskatoon working on plant cell suspension cultures and the nutritional requirements for such cultures. As result of his research activities for th... | Wikipedia - Oluf L. Gamborg - Career | 228 | 1,216 | null |
Section: Early life and education. Klein-Seetharaman was born in Germany. She completed her undergraduate training at the University of Cologne, where she earned dual honours in biology and chemistry. After earning her doctorate, she moved to the United States, where she worked in the laboratory of Har Gobind Khorana a... | Wikipedia - Judith Klein-Seetharaman - Early life and education | 153 | 765 | null |
Section: Selected publications. Valerian E Kagan; Gaowei Mao; Feng Qu; et al. (14 November 2016). "Oxidized arachidonic and adrenic PEs navigate cells to ferroptosis". Nature Chemical Biology. 13 (1): 81–90. doi:10.1038/NCHEMBIO.2238. ISSN 1552-4450. PMC 5506843. PMID 27842066. Wikidata Q33897013. Charleen T. Chu; Jing... | Wikipedia - Judith Klein-Seetharaman - Selected publications | 343 | 943 | null |
Article: Mikael Kubista. Mikael Kubista (born 13 August 1961) is a Czech-born Swedish chemist and entrepreneur who works in the field of molecular diagnostics. Since 2007, he is serving as a Professor of Chemistry and Head of the Department of Gene Expression Profiling at the Biotechnology Institute, Czech Academy of S... | Wikipedia - Mikael Kubista - Summary | 217 | 932 | null |
Section: Education. He completed his undergraduate studies at University of Gothenburg, earning a B.Sc. degree in chemistry in 1984. He then pursued a Licentiate in Physical Chemistry at the Institute of Chemistry and Chemical Engineering, Chalmers University of Technology in Göteborg, which he completed in 1986. Kubis... | Wikipedia - Mikael Kubista - Education | 179 | 937 | null |
Section: Career > Entrepreneurial activities. In 1998 Kubista founded LightUp Technologies AB after his research finding of lightUp probes, a company that specializes in the development of real-time PCR tests for human infectious diseases. Three years later In 2001, Kubista's research led to the establishments of Multi... | Wikipedia - Mikael Kubista - Career > Entrepreneurial activities | 317 | 1,441 | null |
Section: Career > TATAA Biocenter. In 2021 Kubista and his co-founders of TATAA Biocenter, sought external investment to expand the company's capabilities. This led to a partnership with the American investment firm Care Equity, aiming to position TATAA as a leading provider of GLP/GCP-regulated molecular services for ... | Wikipedia - Mikael Kubista - Career > TATAA Biocenter | 341 | 1,690 | null |
Section: Career > Advisory roles and memberships. Kubista holds several positions and advisory roles within the scientific and biotechnology communities including: Roche, ThermoFisher, Qiagen, Bio-Rad, and RealSeq Biosciences. He is also a member of the Scientific Advisory Council of Genetic Engineering News. Kubista h... | Wikipedia - Mikael Kubista - Career > Advisory roles and memberships | 170 | 869 | null |
Section: Career > Selected findings and publications. Studied and identified chromophores and a variety of dyes commonly used as biomolecule labels like: tryptophan, DAPI, fluorescein, thiazole orange, and BEBO. Explained DNA strand exchange in homologous recombination. Applying Widlund experiment, identified specific ... | Wikipedia - Mikael Kubista - Career > Selected findings and publications | 164 | 790 | null |
Section: Biography > Early life and education. Suksin Lee was born in P'yŏngannam-do, Korea, the son of I Myŏngse and a woman of the Koksan Kang family. He earned his medical degree from Kyŏngsŏng Medical College (now Seoul National University) in 1921, and obtained his medical license in August of that year. After gra... | Wikipedia - Suksin Lee - Biography > Early life and education | 244 | 1,221 | null |
Section: Biography > Scientific career. Returning to his native Korea, he began studies of the staple Korean diet and its effects on metabolism as a research assistant at Kyŏngsŏng Medical College in February 1928. He was appointed an instructor of physiology in the department of biochemistry of Severance Union Medical... | Wikipedia - Suksin Lee - Biography > Scientific career | 216 | 1,081 | null |
Section: Contributions. As the first Ph.D. and full-time professor of biochemistry in Korea, Lee contributed to the establishment of biochemistry as a newly organized field of study in Korea. He began with a study of glycolysis. In the late 1920s, the role of phosphorylated compounds in glycolysis had not yet been full... | Wikipedia - Suksin Lee - Contributions | 254 | 1,291 | null |
Section: Research. Lukinavičius completed his bachelor's degree and master's degree in biochemistry at the Vilnius University in 2000 and 2002 respectively. During this period he worked as a research assistant in Saulius Klimašauskas group and investigating conformational movements of the catalytic loop of DNA methyltr... | Wikipedia - Gražvydas Lukinavičius - Research | 332 | 1,603 | null |
Section: Publications. His most-cited publications, according to Google Scholar are: Lukinavičius, G., K. Umezawa, N. Olivier, A. Honigmann, G. Yang, T. Plass, V. Mueller, L. Reymond, I. R. Corrêa, Z.-G. Luo, C. Schultz, E. A. Lemke, P. Heppenstall, C. Eggeling, S. Manley and K. Johnsson (2013). A near-infrared fluorop... | Wikipedia - Gražvydas Lukinavičius - Publications | 339 | 944 | null |
Nature Chemical Biology 2, 31-2. (cited 252 times) Lukinavičius, G., C. Blaukopf, E. Pershagen, A. Schena, L. Reymond, E. Derivery, M. Gonzalez-Gaitan, E. D’Este, S. W. Hell, D. W. Gerlich and Kai Johnsson (2015). SiR–Hoechst is a far-red DNA stain for live-cell nanoscopy. Nature Communications 6, 8497. (Cited 276 time... | Wikipedia - Gražvydas Lukinavičius - Publications | 197 | 537 | null |
Section: Career. From 1928 to 1961, Man worked as a researcher, and technician, and then a professor at Yale. She worked at Lafayette B. Mendel's physiological chemistry lab at Yale with John P. Peters and Herman Yannet where they developed the first test to detect hormone levels in the thyroid gland. The test was call... | Wikipedia - Evelyn Brower Man - Career | 215 | 1,088 | null |
Section: Chemical species. Acetals Hemiacetals Thioacetals Ketals Alcohols and diols Haloalkanes Thiols Alkanes and cycloalkanes Alkenes Alkynes Amines Amino acids, peptides, proteins Aromatics Acetophenones Anilines Anisoles Benzene Benzenesulfonic acids Benzophenones Nitrobenzenes Phenols Aromatic hydrocarbons Toluen... | Wikipedia - Outline of organic chemistry - Chemical species | 191 | 660 | null |
Addition reaction Aldol addition Electrophilic addition Michael addition Mukaiyama aldol addition Nucleophilic addition Cyclization Bergman cyclization Nazarov cyclization reaction Elimination reaction Beta elimination Cope elimination E1cB elimination reaction Hofmann elimination Organic redox reaction Cannizzaro reac... | Wikipedia - Outline of organic chemistry - Reactions | 348 | 1,494 | null |
Article: 1,3-dipole. In organic chemistry, a 1,3-dipolar compound or 1,3-dipole is a dipolar compound with delocalized electrons and a separation of charge over three atoms. They are reactants in 1,3-dipolar cycloadditions. The dipole has at least one resonance structure with positive and negative charges having a 1,3 ... | Wikipedia - 1,3-dipole - Summary | 297 | 929 | null |
Article: Aggregation-induced emission. Aggregation-induced emission (AIE) is a phenomenon in which certain organic luminophores (fluorescent dyes) exhibit stronger emission of light in their aggregated or solid state compared to when they are in solution. This counterintuitive behavior contrasts with most organic compo... | Wikipedia - Aggregation-induced emission - Summary | 164 | 853 | null |
Section: Aggregation-induced emission enhancement. The phenomenon in which organic luminophores show higher photoluminescence efficiency in the aggregated state than in solution is called aggregation-induced emission enhancement (AIEE). Some luminophores, e.g., diketopyrrolopyrrole-based and sulfonamide-based luminopho... | Wikipedia - Aggregation-induced emission - Aggregation-induced emission enhancement | 164 | 711 | null |
Section: History. The flammable nature of the exhalations of wine was already known to ancient natural philosophers such as Aristotle (384–322 BCE), Theophrastus (c. 371–287 BCE), and Pliny the Elder (23/24–79 CE). However, this did not immediately lead to the isolation of alcohol, even despite the development of more ... | Wikipedia - Alcohol (chemistry) - History | 308 | 1,197 | null |
In the twelfth century, recipes for the production of aqua ardens ("burning water", i.e., alcohol) by distilling wine with salt started to appear in a number of Latin works, and by the end of the thirteenth century, it had become a widely known substance among Western European chemists. The works of Taddeo Alderotti (1... | Wikipedia - Alcohol (chemistry) - History | 194 | 799 | null |
Section: Nomenclature > Etymology. The word "alcohol" derives from the Arabic kohl (Arabic: الكحل, romanized: al-kuḥl), a powder used as an eyeliner. The first part of the word (al-) is the Arabic definite article, equivalent to the in English. The second part of the word (kuḥl) has several antecedents in Semitic langu... | Wikipedia - Alcohol (chemistry) - Nomenclature > Etymology | 277 | 1,147 | null |
At the same time Paracelsus uses the word for a volatile liquid; alcool or alcool vini occurs often in his writings. Bartholomew Traheron, in his 1543 translation of John of Vigo, introduces the word as a term used by "barbarous" authors for "fine powder." Vigo wrote: "the barbarous auctours use alcohol, or (as I fynde... | Wikipedia - Alcohol (chemistry) - Nomenclature > Etymology | 344 | 1,209 | null |
The term ethanol was invented in 1892, blending "ethane" with the "-ol" ending of "alcohol", which was generalized as a libfix. The term alcohol originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic drinks. The suffix -ol appears in the ... | Wikipedia - Alcohol (chemistry) - Nomenclature > Etymology | 205 | 898 | null |
Section: Nomenclature > Systematic names. IUPAC nomenclature is used in scientific publications, and in writings where precise identification of the substance is important. In naming simple alcohols, the name of the alkane chain loses the terminal e and adds the suffix -ol, e.g., as in "ethanol" from the alkane chain n... | Wikipedia - Alcohol (chemistry) - Nomenclature > Systematic names | 330 | 1,175 | null |
Section: Nomenclature > Common names. In other less formal contexts, an alcohol is often called with the name of the corresponding alkyl group followed by the word "alcohol", e.g., methyl alcohol, ethyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol, depending on whether the hydroxyl group is bond... | Wikipedia - Alcohol (chemistry) - Nomenclature > Common names | 165 | 698 | null |
Section: Nomenclature > Common names > Primary, secondary, and tertiary. Alcohols are then classified into primary, secondary (sec-, s-), and tertiary (tert-, t-), based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl functional group. The respective numeric shorthands 1°, 2°, and 3... | Wikipedia - Alcohol (chemistry) - Nomenclature > Common names > Primary, secondary, and tertiary | 254 | 911 | null |
Section: Applications. Alcohols have a long history of myriad uses. For simple mono-alcohols, which is the focus on this article, the following are most important industrial alcohols: methanol, mainly for the production of formaldehyde and as a fuel additive ethanol, mainly for alcoholic beverages, fuel additive, solve... | Wikipedia - Alcohol (chemistry) - Applications | 181 | 755 | null |
Section: Occurrence in nature. Alcohols occur widely in nature, as derivatives of glucose such as cellulose and hemicellulose, and in phenols and their derivatives such as lignin. Starting from biomass, 180 billion tons/y of complex carbohydrates (sugar polymers) are produced commercially (as of 2014). Many other alcoh... | Wikipedia - Alcohol (chemistry) - Occurrence in nature | 161 | 677 | null |
Section: Production > Ziegler and oxo processes. In the Ziegler process, linear alcohols are produced from ethylene and triethylaluminium followed by oxidation and hydrolysis. An idealized synthesis of 1-octanol is shown: Al(C2H5)3 + 9 C2H4 → Al(C8H17)3 Al(C8H17)3 + 3O + 3 H2O → 3 HOC8H17 + Al(OH)3 The process generate... | Wikipedia - Alcohol (chemistry) - Production > Ziegler and oxo processes | 211 | 691 | null |
Section: Production > Hydration reactions. Some low molecular weight alcohols of industrial importance are produced by the addition of water to alkenes. Ethanol, isopropanol, 2-butanol, and tert-butanol are produced by this general method. Two implementations are employed, the direct and indirect methods. The direct me... | Wikipedia - Alcohol (chemistry) - Production > Hydration reactions | 164 | 723 | null |
Section: Reactions > Deprotonation. With aqueous pKa values of around 16–19, alcohols are, in general, slightly weaker acids than water. With strong bases such as sodium hydride or sodium they form salts called alkoxides, with the general formula RO−M+ (where R is an alkyl and M is a metal). R−OH + NaH → R−O−Na+ + H2 2... | Wikipedia - Alcohol (chemistry) - Reactions > Deprotonation | 240 | 842 | null |
Section: Reactions > Dehydration. Meanwhile, the oxygen atom has lone pairs of nonbonded electrons that render it weakly basic in the presence of strong acids such as sulfuric acid. For example, with methanol: Upon treatment with strong acids, alcohols undergo the E1 elimination reaction to produce alkenes. The reactio... | Wikipedia - Alcohol (chemistry) - Reactions > Dehydration | 160 | 727 | null |
Section: Reactions > Oxidation. Primary alcohols (R−CH2OH) can be oxidized either to aldehydes (R−CHO) or to carboxylic acids (R−CO2H). The oxidation of secondary alcohols (R1R2CH−OH) normally terminates at the ketone (R1R2C=O) stage. Tertiary alcohols (R1R2R3C−OH) are resistant to oxidation. The direct oxidation of pr... | Wikipedia - Alcohol (chemistry) - Reactions > Oxidation | 235 | 883 | null |
Article: Aldol reactions. In organic chemistry, aldol reactions are acid- or base-catalyzed reactions of aldehydes or ketones. Aldol addition or aldolization refers to the addition of an enolate or enolation as a nucleophile to a carbonyl moiety as an electrophile. This produces a β-hydroxyaldehyde or β-hydroxyketone. ... | Wikipedia - Aldol reactions - Summary | 187 | 784 | null |
Section: Mechanisms. Aldol reactions may proceed by two distinct mechanisms. Carbonyl compounds, such as aldehydes and ketones, can be converted to enols or enol ethers. These species, being nucleophilic at the α-carbon, can attack especially reactive protonated carbonyls such as protonated aldehydes. This is the 'enol... | Wikipedia - Aldol reactions - Mechanisms | 344 | 1,426 | null |
Section: Mechanisms > Enolate mechanism. If the catalyst is a moderate base such as hydroxide ion or an alkoxide, the aldol reaction occurs via nucleophilic attack by the resonance-stabilized enolate on the carbonyl group of another molecule. The product is the alkoxide salt of the aldol product. Then aldol, the aldol ... | Wikipedia - Aldol reactions - Mechanisms > Enolate mechanism | 232 | 969 | null |
Section: Mechanisms > Enol mechanism. When an acid catalyst is used, the initial step in the reaction mechanism involves acid-catalyzed tautomerization of the carbonyl compound to the enol. The acid also serves to activate the carbonyl group of another molecule by protonation, rendering it highly electrophilic. The eno... | Wikipedia - Aldol reactions - Mechanisms > Enol mechanism | 151 | 641 | null |
Section: Intramolecular reaction. Intramolecular aldol condensation is between two aldehyde groups or ketone groups in the same molecule. Five- or six-membered α, β-unsaturated ketone or aldehydes are formed as products. This reaction is an important approach to the formation of carbon-carbon bonds in organic molecules... | Wikipedia - Aldol reactions - Intramolecular reaction | 312 | 1,257 | null |
Article: Alkylidene group. In organic chemistry, alkylidene is a general term for divalent functional groups of the form R2C=, where each R is an alkane or hydrogen. They can be considered the functional group corresponding to mono- or disubstituted divalent carbenes (known as alkylidenes), or as the result of removing... | Wikipedia - Alkylidene group - Summary | 192 | 746 | null |
Section: Nomenclature. In standard IUPAC nomenclature, alkylidene groups are named by replacing the -yl in the corresponding alkyl group with -ylidene. This practice is also often extended to common names. For example, the isopropyl group (IUPAC: prop-2-yl) −CH(CH3)2 corresponds to the isopropylidene group =C(CH3)2 (IU... | Wikipedia - Alkylidene group - Nomenclature | 275 | 1,053 | null |
Conversely, common names of many classes of compounds use alkylidenes in their nomenclature, even though many of them do not formally contain the alkylidene group =CR2, instead containing a substituted methylene bridge −CR2−. Examples include geminal disubstituted alkanes, such as 1,1-dichloroethane being known as ethy... | Wikipedia - Alkylidene group - Nomenclature | 173 | 637 | null |
Section: Reactions. The distinction between alkylidenes and alkenes (or alkenyl groups) is semantic in organic chemistry. The compounds are isomeric, defined by the presence of a carbon-carbon double bond, and undergo similar reactions; thus, reactions involving alkylidene groups are typically described using the broad... | Wikipedia - Alkylidene group - Reactions | 244 | 973 | null |
Section: Reactions. NCAs are prone to hydrolysis to the parent amino acid: RCHNHC(O)OC(O) + H2O → H2NCH(R)CO2H + CO2 Some derivatives however tolerate water briefly. NCAs convert to homopolypeptides ( [N(H)CH(R)CO)]n) through ring-opening polymerization: n RCHNHC(O)OC(O) → [N(H)CH(R)CO)]n + n CO2 Poly-L-lysine has been... | Wikipedia - Amino acid N-carboxyanhydride - Reactions | 240 | 763 | null |
Article: Anti-periplanar. In organic chemistry, anti-periplanar, or antiperiplanar, describes the A−B−C−D bond angle in a molecule. In this conformer, the dihedral angle of the A−B bond and the C−D bond is greater than +150° or less than −150° (Figures 1 and 2). Anti-periplanar is often used in textbooks to mean strict... | Wikipedia - Anti-periplanar - Summary | 278 | 927 | null |
Section: Molecular orbitals. An important factor in the antiperiplanar conformer is the interaction between molecular orbitals. Anti-periplanar geometry will put a bonding orbital and an anti-bonding orbital approximately parallel to each other, or syn-periplanar. Figure 6 is another representation of 2-chloro-2,3-dime... | Wikipedia - Anti-periplanar - Molecular orbitals | 326 | 1,259 | null |
Section: Examples of anti-periplanar geometry in mechanisms > E2 mechanism. A bimolecular elimination reaction will occur in a molecule where the breaking carbon-hydrogen bond and the leaving group are anti-periplanar (Figure 8). This geometry is preferred because it aligns σC-H and σ*C-X orbitals. Figure 9 shows the σ... | Wikipedia - Anti-periplanar - Examples of anti-periplanar geometry in mechanisms > E2 mechanism | 174 | 660 | null |
Article: Aroma compound. An aroma compound, also known as an odorant, aroma, fragrance, flavoring or flavor, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently volatile for transmission via the air to the olf... | Wikipedia - Aroma compound - Summary | 304 | 1,525 | null |
Section: Other aroma compounds > Aldehydes. High concentrations of aldehydes tend to be very pungent and overwhelming, but low concentrations can evoke a wide range of aromas. Acetaldehyde (ethereal) Hexanal (green, grassy) cis-3-Hexenal (green tomatoes) Furfural (burnt oats) Hexyl cinnamaldehyde Isovaleraldehyde – nut... | Wikipedia - Aroma compound - Other aroma compounds > Aldehydes | 163 | 547 | null |
Section: Other aroma compounds > Thiols. Thioacetone (2-propanethione) A lightly studied organosulfur. Its smell is so potent it can be detected several hundred meters downwind mere seconds after a container is opened. Allyl thiol (2-propenethiol; allyl mercaptan; CH2=CHCH2SH) (garlic volatiles and garlic breath) (Meth... | Wikipedia - Aroma compound - Other aroma compounds > Thiols | 277 | 989 | null |
Section: Safety and regulation. In 2005–06, fragrance mix was the third-most-prevalent allergen in patch tests (11.5%). 'Fragrance' was voted Allergen of the Year in 2007 by the American Contact Dermatitis Society. An academic study in the United States published in 2016 has shown that "34.7 % of the population reporte... | Wikipedia - Aroma compound - Safety and regulation | 281 | 1,405 | null |
Article: Arrow pushing. Arrow pushing or electron pushing is a technique used to describe the progression of organic chemistry reaction mechanisms. It was first developed by Sir Robert Robinson. In using arrow pushing, "curved arrows" or "curly arrows" are drawn on the structural formulae of reactants in a chemical equ... | Wikipedia - Arrow pushing - Summary | 203 | 1,093 | null |
Section: Notation. The representation of reaction mechanisms using curved arrows to indicate electron flow was developed by Sir Robert Robinson in 1922. Organic chemists use two types of arrows within molecular structures to describe electron movements. Single electrons’ trajectories are designated with single barbed a... | Wikipedia - Arrow pushing - Notation | 328 | 1,700 | null |
Section: Breaking of bonds > Homolytic bond cleavage. Homolytic bond cleavage is a process where the electron pair comprising a bond is split, causing the bond to break. This is denoted by two single barbed curved arrows pointing away from the bond. The consequence of this process is the retention of a single unpaired ... | Wikipedia - Arrow pushing - Breaking of bonds > Homolytic bond cleavage | 207 | 1,012 | null |
Section: Breaking of bonds > SN1 reactions. An SN1 reaction occurs when a molecule separates into a positively charged component and a negatively charged component. This generally occurs in highly polar solvents through a process called solvolysis. The positively charged component then reacts with a nucleophile forming... | Wikipedia - Arrow pushing - Breaking of bonds > SN1 reactions | 284 | 1,238 | null |
Section: Breaking of bonds > SN2 reactions. An SN2 reaction occurs when a nucleophile displaces a leaving group residing on a molecule from the backside of the leaving group. This displacement or substitution results in the formation of a substitution product with inversion of stereochemical configuration. The nucleoph... | Wikipedia - Arrow pushing - Breaking of bonds > SN2 reactions | 256 | 1,208 | null |
Section: Breaking of bonds > E2 eliminations. An E2 elimination occurs when a proton adjacent to a leaving group is extracted by a base with simultaneous elimination of a leaving group and generation of a double bond. Similar to the relationship between E1 eliminations and SN1 mechanisms, E2 eliminations often occur in... | Wikipedia - Arrow pushing - Breaking of bonds > E2 eliminations | 205 | 959 | null |
Section: Breaking of bonds > Addition reactions. Addition reactions occur when nucleophiles react with carbonyls. When a nucleophile adds to a simple aldehyde or ketone, the result is a 1,2-addition. When a nucleophile adds to a conjugated carbonyl system, the result is a 1,4-addition. The designations 1,2 and 1,4 are ... | Wikipedia - Arrow pushing - Breaking of bonds > Addition reactions | 165 | 647 | null |
Article: Azomethine ylide. Azomethine ylides are nitrogen-based 1,3-dipoles, consisting of an iminium ion next to a carbanion. They are used in 1,3-dipolar cycloaddition reactions to form five-membered heterocycles, including pyrrolidines and pyrrolines. These reactions are highly stereo- and regioselective, and have t... | Wikipedia - Azomethine ylide - Summary | 174 | 666 | null |
Section: Structure. The resonance structures below show the 1,3-dipole contribution, in which the two carbon atoms adjacent to the nitrogen have a negative or positive charge. The most common representation of azomethine ylides is that in which the nitrogen is positively charged, and the negative charge is shared betwe... | Wikipedia - Azomethine ylide - Structure | 348 | 1,459 | null |
Section: Generation > From aziridines. Azomethine ylides can be generated from ring opening of aziridines. In accordance with the Woodward–Hoffmann rules, the thermal four-electron ring opening proceeds via a conrotatory process, whereas the photochemical reaction is disrotatory. In this ring opening reaction, there is... | Wikipedia - Azomethine ylide - Generation > From aziridines | 165 | 658 | null |
Section: 1,3-dipolar cycloaddition reactions. As with other cycloaddition reactions of a 1,3-dipole with a π-system, 1,3-dipolar cycloaddition using an azomethine ylide is a six-electron process. According to the Woodward–Hoffmann rules, this addition is suprafacial with respect to both the dipole and dipolarophile. Th... | Wikipedia - Azomethine ylide - 1,3-dipolar cycloaddition reactions | 333 | 1,215 | null |
1,3-Dipolar cycloaddition reactions of azomethine ylides commonly use alkenes or alkynes as dipolarophiles, to form pyrrolidines or pyrrolines, respectively. A reaction of an azomethine ylide with an alkene is shown above, and results in a pyrrolidine. This kind of reactions can be used to synthesis Ullazine. While dip... | Wikipedia - Azomethine ylide - 1,3-dipolar cycloaddition reactions | 295 | 1,157 | null |
Section: 1,3-dipolar cycloaddition reactions > Stereoselectivity of cycloadditions. Unlike most 1,3-dipolar cycloaddition reactions, in which the stereochemistry of the dipole is lost or non-existent, azomethine ylides are able to retain their stereochemistry. This is generally done by ring opening of an aziridine, and... | Wikipedia - Azomethine ylide - 1,3-dipolar cycloaddition reactions > Stereoselectivity of cycloadditions | 154 | 564 | null |
Section: 1,3-dipolar cycloaddition reactions > Enantioselective synthesis. Enantioselective cycloaddition of azomethine ylides using chiral catalysts was first described in a seminal work by Allway and Grigg in 1991. This powerful method was further developed by Jørgensen and Zhang. These reactions generally use zinc, ... | Wikipedia - Azomethine ylide - 1,3-dipolar cycloaddition reactions > Enantioselective synthesis | 152 | 645 | null |
Section: Other reactions > Electrocyclizations. Conjugated azomethine ylides are capable of [1,5]- and [1,7]-electrocyclizations. An example of a [1,7]-electrocyclization of a diphenylethenyl-substituted azomethine ylide is shown below. This conrotatory ring-closing is followed by a suprafacial [1,5]-hydride shift, whi... | Wikipedia - Azomethine ylide - Other reactions > Electrocyclizations | 166 | 605 | null |
Article: Polymer backbone. In polymer science, the polymer chain or simply backbone of a polymer is the main chain of a polymer. Polymers are often classified according to the elements in the main chains. The character of the backbone, i.e. its flexibility, determines the properties of the polymer (such as the glass tr... | Wikipedia - Polymer backbone - Summary | 162 | 743 | null |
Section: Organic polymers. Common synthetic polymers have main chains composed of carbon, i.e. C-C-C-C.... Examples include polyolefins such as polyethylene ((CH2CH2)n) and many substituted derivative ((CH2CH(R))n) such as polystyrene (R = C6H5), polypropylene (R = CH3), and acrylates (R = CO2R'). Other major classes o... | Wikipedia - Polymer backbone - Organic polymers | 209 | 592 | null |
Section: Biopolymers > Proteins and peptides. Proteins are characterized by amide linkages (-N(H)-C(O)-) formed by the condensation of amino acids. The sequence of the amino acids in the polypeptide backbone is known as the primary structure of the protein. Like almost all polymers, protein fold and twist, forming into... | Wikipedia - Polymer backbone - Biopolymers > Proteins and peptides | 194 | 911 | null |
Section: Biopolymers > Carbohydrates. Carbohydrates arise by condensation of monosaccharides such as glucose. The polymers can be classified into oligosaccharides (up to 10 residues) and polysaccharides (up to about 50,000 residues). The backbone chain is characterized by an ether bond between individual monosaccharide... | Wikipedia - Polymer backbone - Biopolymers > Carbohydrates | 324 | 1,335 | null |
Section: Biopolymers > Nucleic acids. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the main examples of polynucleotides. They arise by condensation of nucleotides. Their backbones form by the condensation of a hydroxy group on a ribose with the phosphate group on another ribose. This linkage is called a p... | Wikipedia - Polymer backbone - Biopolymers > Nucleic acids | 184 | 762 | null |
Article: Beilstein database. The Beilstein database is a database in the field of organic chemistry, in which compounds are uniquely identified by their Beilstein Registry Number. The database covers the scientific literature from 1771 to the present and contains experimentally validated information on millions of chem... | Wikipedia - Beilstein database - Summary | 282 | 1,509 | null |
Section: History. Beilstein was founded as German-language standard reference work for organic chemistry was intended to supplement the content of the Chemisches Zentralblatt. In light of the leading role of German chemistry in international science, Beilstein's handbook quickly became renowned as a standard reference ... | Wikipedia - Beilstein database - History | 202 | 1,001 | null |
Article: Biocatalysis. Biocatalysis refers to the use of living (biological) systems or their parts to speed up (catalyze) chemical reactions. In biocatalytic processes, natural catalysts, such as enzymes, perform chemical transformations on organic compounds. Both enzymes that have been more or less isolated and enzym... | Wikipedia - Biocatalysis - Summary | 161 | 874 | null |
Section: History. Biocatalysis underpins some of the oldest chemical transformations known to humans, for brewing predates recorded history. The oldest records of brewing are about 6000 years old and refer to the Sumerians. The employment of enzymes and whole cells have been important for many industries for centuries.... | Wikipedia - Biocatalysis - History | 214 | 1,036 | null |
Section: Advantages of chemoenzymatic synthesis. -Enzymes are environmentally benign, being completely degraded in the environment. -Most enzymes typically function under mild or biological conditions, which minimizes problems of undesired side-reactions such as decomposition, isomerization, racemization and rearrangem... | Wikipedia - Biocatalysis - Advantages of chemoenzymatic synthesis | 350 | 1,775 | null |
Section: Asymmetric biocatalysis. The use of biocatalysis to obtain enantiopure compounds can be divided into two different methods: Kinetic resolution of a racemic mixture Biocatalyzed asymmetric synthesis In kinetic resolution of a racemic mixture, the presence of a chiral object (the enzyme) converts one of the ster... | Wikipedia - Biocatalysis - Asymmetric biocatalysis | 313 | 1,456 | null |
Such reactions must therefore be terminated before equilibrium is reached. If it is possible to perform such resolutions under conditions where the two substrate- enantiomers are racemizing continuously, all substrate may in theory be converted into enantiopure product. This is called dynamic resolution. In biocatalyze... | Wikipedia - Biocatalysis - Asymmetric biocatalysis | 327 | 1,431 | null |
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