Tan, Li’s team published research in Journal of Colloid and Interface Science in 2018 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers. Ethers lack the hydroxyl groups of alcohols. Without the strongly polarized O―H bond, ether molecules cannot engage in hydrogen bonding with each other. Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamateIn 2018 ,《Synthesis of thermo-responsive nanocomposites of superparamagnetic cobalt nanoparticles/poly(N-isopropylacrylamide)》 was published in Journal of Colloid and Interface Science. The article was written by Tan, Li; Liu, Bing; Siemensmeyer, Konrad; Glebe, Ulrich; Boeker, Alexander. The article contains the following contents:

Novel nanocomposites of superparamagnetic cobalt nanoparticles (Co NPs) and poly(N-isopropylacrylamide) (PNIPAM) were fabricated through surface-initiated atom-transfer radical polymerization (SI-ATRP). We firstly synthesized a functional ATRP initiator, containing an amine (as anchoring group) and a 2-bromopropionate group (SI-ATRP initiator). Oleic acid- and trioctylphosphine oxide-coated Co NPs were then modified with the initiator via ligand exchange. The process is facile and rapid for efficient surface functionalization and afterwards the Co NPs can be dispersed into polar solvent DMF without aggregation. Transmission electron microscopy, Fourier transform IR spectroscopy, XPS, and dynamic light scattering measurements confirmed the success of ligand exchange. The following polymerization of NIPAM was conducted on the surface of Co NPs. Temperature-dependent dynamic light scattering study showed the responsive behavior of PNIPAM-coated Co NPs. The combination of superparamagnetic and thermo-responsive properties in these hybrid nanoparticles is promising for future applications e.g. in biomedicine.tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate) was used in this study.

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers. Ethers lack the hydroxyl groups of alcohols. Without the strongly polarized O―H bond, ether molecules cannot engage in hydrogen bonding with each other. Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Liu, Gang’s team published research in European Journal of Medicinal Chemistry in 2019 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.The C-O bonds that comprise simple ethers are strong. Electric Literature of C9H19NO4 They are unreactive toward all but the strongest bases. Although generally of low chemical reactivity, they are more reactive than alkanes.

Electric Literature of C9H19NO4In 2019 ,《Structure-activity relationship studies on Bax activator SMBA1 for the treatment of ER-positive and triple-negative breast cancer》 was published in European Journal of Medicinal Chemistry. The article was written by Liu, Gang; Yin, Tao; Kim, Hyejin; Ding, Chunyong; Yu, Zhuo; Wang, Hong; Chen, Haiying; Yan, Ruping; Wold, Eric A.; Zou, Hao; Liu, Xi; Ding, Ye; Shen, Qiang; Zhou, Jia. The article contains the following contents:

In an effort to develop novel Bax activators for breast cancer treatment, a series of diverse analogs have been designed and synthesized based on lead compound SMBA1 through several strategies, including introducing various alkylamino side chains to have a deeper access to S184 pocket, replacing carbon atoms with nitrogen, and reducing the nitro group of 9H-fluorene scaffold. Compounds 14 (CYD-2-11, I) and 49 (CYD-4-61, II) have been identified to exhibit significantly improved antiproliferative activity compared to SMBA1, with IC50 values of 3.22 μM and 0.07 μM against triple-neg. breast cancer MDA-MB-231 and 3.81 μM and 0.06 μM against ER-pos. breast cancer MCF-7 cell lines, resp. Mechanism of action studies of II indicated that it can activate Bax protein to induce cytochrome c release and regulate apoptotic biomarkers, leading to cancer cell apoptosis. Further in vivo efficacy studies of I and II in nude mice bearing MDA-MB-231 tumor xenografts demonstrated that these drug candidates can significantly suppress tumor growth, indicating their therapeutic potential for the treatment of breast cancer. In addition to this study using tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate, there are many other studies that have used tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Electric Literature of C9H19NO4) was used in this study.

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.The C-O bonds that comprise simple ethers are strong. Electric Literature of C9H19NO4 They are unreactive toward all but the strongest bases. Although generally of low chemical reactivity, they are more reactive than alkanes.

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Mori, Ryota’s team published research in European Journal of Medicinal Chemistry in 2014 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Oxygen is more electronegative than carbon, thus the alpha hydrogens of ethers are more acidic than those of simple hydrocarbons. They are far less acidic than alpha hydrogens of carbonyl groups (such as in ketones or aldehydes), however. Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

In 2014,Mori, Ryota; Kato, Asako; Komenoi, Kousuke; Kurasaki, Haruaki; Iijima, Touru; Kawagoshi, Masashi; Kiran, Y. B.; Takeda, Sho; Sakai, Norio; Konakahara, Takeo published 《Synthesis and in vitro antitumor activity of novel 2-alkyl-5-methoxycarbonyl-11-methyl-6H-pyrido[4,3-b]carbazol-2-ium and 2-(alkyl)ellipticin-2-ium chloride derivatives》.European Journal of Medicinal Chemistry published the findings.Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate The information in the text is summarized as follows:

Twenty-one types of ellipticine derivatives [5,11-dimethyl-6H-pyrido[4,3-b]carbazole derivatives] and pyridocarbazole derivatives (5-methoxycarbonyl-11-methyl-6H-pyrido[4,3-b]carbazoles) with a (nitroso)urea group linked by an (oxy)bis[ethylene] unit at the 2-position, were designed and the synthesis of the target compounds was achieved by a multi-step pathway. Their cytotoxicity against HeLa S-3 cells (human uterine cervical carcinoma cell line) was evaluated. The title compounds thus formed included 2,5,11-trimethyl-6H-pyrido[4,3-b]carbazolium chloride and related substances. Some of these new compounds exhibited potent antitumor activity by comparison with that of ellipticine. In the experiment, the researchers used tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate)

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Oxygen is more electronegative than carbon, thus the alpha hydrogens of ethers are more acidic than those of simple hydrocarbons. They are far less acidic than alpha hydrogens of carbonyl groups (such as in ketones or aldehydes), however. Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Wang, Siwen’s team published research in European Journal of Medicinal Chemistry in 2019 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Ethers do have nonbonding electron pairs on their oxygen atoms, and they can form hydrogen bonds with other molecules (alcohols, amines, etc.) that have O―H or N―H bonds. The ability to form hydrogen bonds with other compounds makes ethers particularly good solvents for a wide variety of organic compounds and a surprisingly large number of inorganic compounds.Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

In 2019,European Journal of Medicinal Chemistry included an article by Wang, Siwen; Yang, Dazhou; Singh, Mandeep; Joo, Hyun; Rangel, Vanessa M.; Tran, Aaron; Phan, Erich; Xue, Liang. Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate. The article was titled 《Thiazole orange – Spermine conjugate: A potent human telomerase inhibitor comparable to BRACO-19》. The information in the text is summarized as follows:

In this report, we synthesized a series of TO conjugates containing different amino side chains and investigated their binding to telomeric G-quadruplex DNA (G4) using several biophys. methods including fluorometric titration and thermal denaturation monitored by fluorescence and CD. The composition of side chains strongly affects the binding of these mols. to G-quadruplex DNA. Incorporation of amino side chains increases the binding affinity of TO toward G4 but has a minimal effect on its selectivity for G4 over duplex DNA. The plausible binding modes are a synergistic effect of end-stacking and groove interactions as indicated by docking studies. Inhibition of human telomerase activity by TO derivatives was determined in vitro by the TRAP assay. Several derivatives can selectively inhibit the activity of telomerase over DNA polymerase at low concentrations More significantly, TO-spermine conjugate (16) exhibits a remarkable effect on telomerase inhibition in the submicromolar range, which is comparable to the inhibition effect of a well-known G4 ligand, BRACO-19. Our results here provide guidance of utilizing TO derivatives as a viable scaffold to design novel G4 ligands, G4 probes, and potent telomerase inhibitors. After reading the article, we found that the author used tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate)

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Ethers do have nonbonding electron pairs on their oxygen atoms, and they can form hydrogen bonds with other molecules (alcohols, amines, etc.) that have O―H or N―H bonds. The ability to form hydrogen bonds with other compounds makes ethers particularly good solvents for a wide variety of organic compounds and a surprisingly large number of inorganic compounds.Safety of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Liu, Zhenzhen’s team published research in Advanced Materials (Weinheim, Germany) in 2014 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Oxygen is more electronegative than carbon, thus the alpha hydrogens of ethers are more acidic than those of simple hydrocarbons. Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate They are far less acidic than alpha hydrogens of carbonyl groups (such as in ketones or aldehydes), however.

In 2014,Liu, Zhenzhen; Lin, Qiuning; Sun, Yun; Liu, Tao; Bao, Chunyan; Li, Fuyou; Zhu, Linyong published 《Spatiotemporally Controllable and Cytocompatible Approach Builds 3D Cell Culture Matrix by Photo-Uncaged-Thiol Michael Addition Reaction [Erratum to document cited in CA161:181639]》.Advanced Materials (Weinheim, Germany) published the findings.Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate The information in the text is summarized as follows:

Due to an error in the mol. structure, the macrocycles in the Table of Contents, Scheme 1, and Figure S1 were incorrect; the corrected structure is given. In the experiment, the researchers used many compounds, for example, tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate)

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Oxygen is more electronegative than carbon, thus the alpha hydrogens of ethers are more acidic than those of simple hydrocarbons. Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate They are far less acidic than alpha hydrogens of carbonyl groups (such as in ketones or aldehydes), however.

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Singh, Vijay’s team published research in Journal of the American Chemical Society in 2013 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Oxygen is more electronegative than carbon, thus the alpha hydrogens of ethers are more acidic than those of simple hydrocarbons. They are far less acidic than alpha hydrogens of carbonyl groups (such as in ketones or aldehydes), however. Electric Literature of C9H19NO4

In 2013,Singh, Vijay; Wang, Shenliang; Kool, Eric T. published 《Genetically Encoded Multispectral Labeling of Proteins with Polyfluorophores on a DNA Backbone》.Journal of the American Chemical Society published the findings.Electric Literature of C9H19NO4 The information in the text is summarized as follows:

Genetically encoded methods for protein conjugation are of high importance as biol. tools. Here the authors describe the development of a new class of dyes for genetically encoded tagging that add new capabilities for protein reporting and detection via HaloTag methodol. Oligodeoxyfluorosides (ODFs) are short DNA-like oligomers in which the natural nucleic acid bases are replaced by interacting fluorescent chromophores, yielding a broad range of emission colors using a single excitation wavelength. The authors describe the development of an alkyl halide dehalogenase-compatible chloroalkane linker phosphoramidite derivative that enables the rapid automated synthesis of many possible dyes for protein conjugation. Experiments to test the enzymic self-conjugation of nine different DNA-like dyes to proteins with HaloTag domains in vitro were performed, and the data confirmed the rapid and efficient covalent labeling of the proteins. Notably, a number of the ODF dyes increase in brightness or change color upon protein conjugation. Tests in mammalian cellular settings revealed that the dyes are functional in multiple cellular contexts, both on the cell surface and within the cytoplasm, allowing protein localization to be imaged in live cells by epifluorescence and laser confocal microscopy. The experimental process involved the reaction of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Electric Literature of C9H19NO4)

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Oxygen is more electronegative than carbon, thus the alpha hydrogens of ethers are more acidic than those of simple hydrocarbons. They are far less acidic than alpha hydrogens of carbonyl groups (such as in ketones or aldehydes), however. Electric Literature of C9H19NO4

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Serebrenik, Yevgeniy V.’s team published research in Molecular Biology of the Cell in 2018 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Ethers do have nonbonding electron pairs on their oxygen atoms, and they can form hydrogen bonds with other molecules (alcohols, amines, etc.) that have O―H or N―H bonds. The ability to form hydrogen bonds with other compounds makes ethers particularly good solvents for a wide variety of organic compounds and a surprisingly large number of inorganic compounds.Product Details of 139115-91-6

In 2018,Serebrenik, Yevgeniy V.; Hellerschmied, Doris; Toure, Momar; Lopez-Giraldez, Francesc; Brookner, Dennis; Crews, Craig M. published 《Targeted protein unfolding uncovers a Golgi-specific transcriptional stress response》.Molecular Biology of the Cell published the findings.Product Details of 139115-91-6 The information in the text is summarized as follows:

In eukaryotic cells, organelle-specific stress-response mechanisms are vital for maintaining cellular homeostasis. The Golgi apparatus, an essential organelle of the secretory system, is the major site of protein modification and sorting within a cell and functions as a platform for spatially regulated signaling. Golgi homeostasis mechanisms that regulate organelle structure and ensure precise processing and localization of protein substrates remain poorly understood. Using a chem. biol. strategy to induce protein unfolding, we uncover a Golgi-specific transcriptional response. An RNA-sequencing profile of this stress response compared with the current state-of-the-art Golgi stressors, nigericin and xyloside, demonstrates the enhanced precision of Golgi targeting achieved with our system. The data set further reveals previously uncharacterized genes that we find to be essential for Golgi structural integrity. These findings highlight the Golgi′s ability to sense misfolded proteins and establish new aspects of Golgi autoregulation. In addition to this study using tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate, there are many other studies that have used tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Product Details of 139115-91-6) was used in this study.

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Ethers do have nonbonding electron pairs on their oxygen atoms, and they can form hydrogen bonds with other molecules (alcohols, amines, etc.) that have O―H or N―H bonds. The ability to form hydrogen bonds with other compounds makes ethers particularly good solvents for a wide variety of organic compounds and a surprisingly large number of inorganic compounds.Product Details of 139115-91-6

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Tarapdar, Abed’s team published research in Beilstein Journal of Organic Chemistry in 2018 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.The C-O bonds that comprise simple ethers are strong. Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate They are unreactive toward all but the strongest bases. Although generally of low chemical reactivity, they are more reactive than alkanes.

In 2018,Beilstein Journal of Organic Chemistry included an article by Tarapdar, Abed; Norris, James K. S.; Sampson, Oliver; Mukamolova, Galina; Hodgkinson, James T.. Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate. The article was titled 《The design and synthesis of an antibacterial phenothiazine-siderophore conjugate》. The information in the text is summarized as follows:

Siderophore-antibiotic conjugates consist of an antibiotic covalently linked by a tether to a siderophore. Such conjugates can demonstrate enhanced uptake and internalisation to the bacterial cell resulting in significantly reduced MIC values and extended spectrum of activity. Phenothiazines are a class of small mols. that have been identified as a potential treatment for multidrug resistant tuberculosis and latent TB. Herein we report the design and synthesis of the first phenothiazine-siderophore conjugate. A convergent synthetic route was developed whereby the functionalised phenothiazine component was prepared in four steps and the siderophore component also prepared in four steps. In M. smegmatis the functionalised phenothiazine demonstrated an equipotent MIC value in direct comparison to the parent phenothiazine from which it was derived. The final conjugate was synthesized by amide bond formation between the two components and global deprotection of the PMB protecting groups to unmask the catechol iron chelating groups of the siderophore. The synthesis is readily amenable to the preparation of analogs whereby the siderophore component of the conjugate can be modified. The route will be used to prepare a library of siderophore-phenothiazine conjugates for full biol. evaluation of much needed new antibacterial agents. The results came from multiple reactions, including the reaction of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate)

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.The C-O bonds that comprise simple ethers are strong. Application In Synthesis of tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate They are unreactive toward all but the strongest bases. Although generally of low chemical reactivity, they are more reactive than alkanes.

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Lercher, Lukas’s team published research in Angewandte Chemie, International Edition in 2013 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Although ethers resist hydrolysis, they are cleaved by hydrobromic acid and hydroiodic acid. Hydrogen chloride cleaves ethers only slowly. Formula: C9H19NO4

In 2013,Lercher, Lukas; McGouran, Joanna F.; Kessler, Benedikt M.; Schofield, Christopher J.; Davis, Benjamin G. published 《DNA Modification under Mild Conditions by Suzuki-Miyaura Cross-Coupling for the Generation of Functional Probes》.Angewandte Chemie, International Edition published the findings.Formula: C9H19NO4 The information in the text is summarized as follows:

We described an efficient method for the introduction of a variety of sensitive and useful functional groups by Suzuki-Miyaura cross-coupling to halogenated pyrimidine bases. After reading the article, we found that the author used tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Formula: C9H19NO4)

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.Although ethers resist hydrolysis, they are cleaved by hydrobromic acid and hydroiodic acid. Hydrogen chloride cleaves ethers only slowly. Formula: C9H19NO4

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem

Katoh, Taisuke’s team published research in Bioorganic & Medicinal Chemistry Letters in 2017 | CAS: 139115-91-6

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.The C-O bonds that comprise simple ethers are strong. They are unreactive toward all but the strongest bases. Although generally of low chemical reactivity, they are more reactive than alkanes. Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

In 2017,Katoh, Taisuke; Yoshikawa, Masato; Yamamoto, Takeshi; Arai, Ryosuke; Nii, Noriyuki; Tomata, Yoshihide; Suzuki, Shinkichi; Koyama, Ryoukichi; Negoro, Nobuyuki; Yogo, Takatoshi published 《Parallel fluorescent probe synthesis based on the large-scale preparation of BODIPY FL propionic acid》.Bioorganic & Medicinal Chemistry Letters published the findings.Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate The information in the text is summarized as follows:

We describe a methodol. for quick development of fluorescent probes with the desired potency for the target of interest by using a method of parallel synthesis, termed as Parallel Fluorescent Probe Synthesis (Parallel-FPS). BODIPY FL propionic acid 1 is a widely used fluorophore, but it is difficult to prepare a large amount of 1, which hinders its use in parallel synthesis. Optimization of a synthetic scheme enabled us to obtain 50 g of 1 in one batch. With this large quantity of 1 in hand, we performed Parallel-FPS of BODIPY FL-labeled ligands for estrogen related receptor-α (ERRα). An initial trial of the parallel synthesis with various linkers provided a potent ligand for ERRα (Reporter IC50 = 80 nM), demonstrating the usefulness of Parallel-FPS.tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate) was used in this study.

tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate(cas: 139115-91-6) belongs to ethers.The C-O bonds that comprise simple ethers are strong. They are unreactive toward all but the strongest bases. Although generally of low chemical reactivity, they are more reactive than alkanes. Recommanded Product: tert-Butyl (2-(2-hydroxyethoxy)ethyl)carbamate

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem