Tag: M.W=200-250

Iodide is one of the largest monatomic anions. It is assigned a radius of around 206 picometers. 1120-90-7, formula is C5H4IN, Name is 3-Iodopyridine.For comparison, the lighter halides are considerably smaller: bromide (196 pm), chloride (181 pm), and fluoride (133 pm). In part because of its size, iodide forms relatively weak bonds with most elements. Recommanded Product: 3-Iodopyridine.

Mcnamee, Ryan E.;Haugland, Marius M.;Nugent, Jeremy;Chan, Rachel;Christensen, Kirsten E.;Anderson, Edward A. research published 《 Synthesis of 1,3-disubstituted bicyclo[1.1.0]butanes via directed bridgehead functionalization》, the research content is summarized as follows. Bicyclo[1.1.0]butanes (BCBs) are increasingly valued as intermediates in ‘strain release’ chem. for the synthesis of substituted four membered rings and bicyclo[1.1.1]pentanes, with applications including bioconjugation processes. Variation of the BCB bridgehead substituents can be challenging due to the inherent strain of the bicyclic scaffold, often necessitating linear syntheses of specific BCB targets. Here authors report the first palladium catalyzed cross-coupling on pre-formed BCBs which enables a ‘late stage’ diversification of the bridgehead position, and the conversion of the resultant products into a range of useful small ring building blocks.

1120-90-7, 3-Iodopyridine is a heteroaryl halide. It undergoes microwave-assisted coupling with heterocyclic compounds (pyrazole, imidazole, pyrrole and indole) to afford the corresponding N-3-pyridinyl-substituted heterocyclic compounds.

3-Iodopyridine is a useful research chemical used as a reactant in the copper-catalyzed coupling of alkylamines and aryl iodides.

3-Iodopyridine is an isomeric compound that can be synthesized by cross-coupling reactions. This compound has been shown to have nicotinic acetylcholine receptor binding properties and may be useful in the treatment of Alzheimer’s disease. 3-Iodopyridine is a primary amino acid that can be used for the synthesis of amines, which are nitrogen nucleophiles. It has been crystallized with halides and its x-ray structures have been determined. The nmr spectra of 3-iodopyridine show that it contains phosphorus and nitrogen atoms. 3-Iodopyridine is also able to take up nitrate ions from solution, which may be due to its uptake properties., Recommanded Product: 3-Iodopyridine

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

Organic iodides are used in veterinary products (Organic Iodide Powder) as a nutritional source of iodine. 5029-67-4, formula is C5H4IN, Name is 2-Iodopyridine. In the chemical industry, alkyl iodides serve as excellent alkylating agents and, specifically, methyl iodide is used as a methylating agent in the synthesis of various pharmaceutical drugs. Related Products of 5029-67-4.

Mcnamee, Ryan E.;Haugland, Marius M.;Nugent, Jeremy;Chan, Rachel;Christensen, Kirsten E.;Anderson, Edward A. research published 《 Synthesis of 1,3-disubstituted bicyclo[1.1.0]butanes via directed bridgehead functionalization》, the research content is summarized as follows. Bicyclo[1.1.0]butanes (BCBs) are increasingly valued as intermediates in ‘strain release’ chem. for the synthesis of substituted four membered rings and bicyclo[1.1.1]pentanes, with applications including bioconjugation processes. Variation of the BCB bridgehead substituents can be challenging due to the inherent strain of the bicyclic scaffold, often necessitating linear syntheses of specific BCB targets. Here authors report the first palladium catalyzed cross-coupling on pre-formed BCBs which enables a ‘late stage’ diversification of the bridgehead position, and the conversion of the resultant products into a range of useful small ring building blocks.

5029-67-4, 2-Iodopyridine can be synthesized from 2-chloropyridine or 2-bromopyridine via treatment with iodotrimethylsilane.
2-Iodopyridine, also known as 2-Iodopyridine, is a useful research compound. Its molecular formula is C5H4IN and its molecular weight is 205 g/mol. The purity is usually 95%.
2-Iodopyridine is a halogenated building block. It is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors
2-Iodopyridine is a white crystalline solid that is soluble in water, alcohol, and ether. The molecule contains a methyl group and two iodine atoms. 2-Iodopyridine has several industrial uses. It acts as a precursor to various pharmaceuticals and agrochemicals. The compound also exhibits insulin resistance properties, which may be related to its ability to bind to the insulin receptor and inhibit insulin signaling. 2-Iodopyridine can also be used for treating cancer because it binds to the DNA of cancer cells, preventing replication and leading to cell death.
2-Iodopyridine is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors., Related Products of 5029-67-4

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

In general, organic iodides are light-sensitive and turn yellow during storage, owing to the formation of iodine. 1120-90-7, formula is C5H4IN, Name is 3-Iodopyridine.Organic iodides can be alkyl, alkenyl, or alkynyl, and all of them are very reactive toward with many kinds of nucleophiles. Application In Synthesis of 1120-90-7.

Meng, Qi;Zhang, Lian;Zhu, Xinhui;Teng, Qiaoqiao research published 《 Synthesis of 9-O-Arylated Berberine with a Polystyrene Resin Supported Copper(II) Catalyst》, the research content is summarized as follows. A series of polyfluorobenzene, pyridine and aniline substituted berberine derivatives I (Ar = Ph, 4-H₂NC₆H₄, 3-pyridyl, etc.) were prepared via resin-supported Cu(II) catalyzed cross-coupling reactions of tetrahydroberberrubine with iodoarenes and subsequent I₂ oxidation The best catalyst, a polyethyleneimine functionalized polystyrene supported Cu²⁺ (PSAPA·Cu(II)), could be reused for at least 5 runs without significant loss of catalytic activity. Comparative studies on the morphol. and porous structures of the materials suggested a catalyst with a moderate sp. surface area and larger pore diameters was more active in catalyzing the cross-coupling reactions.

1120-90-7, 3-Iodopyridine is a heteroaryl halide. It undergoes microwave-assisted coupling with heterocyclic compounds (pyrazole, imidazole, pyrrole and indole) to afford the corresponding N-3-pyridinyl-substituted heterocyclic compounds.

3-Iodopyridine is a useful research chemical used as a reactant in the copper-catalyzed coupling of alkylamines and aryl iodides.

3-Iodopyridine is an isomeric compound that can be synthesized by cross-coupling reactions. This compound has been shown to have nicotinic acetylcholine receptor binding properties and may be useful in the treatment of Alzheimer’s disease. 3-Iodopyridine is a primary amino acid that can be used for the synthesis of amines, which are nitrogen nucleophiles. It has been crystallized with halides and its x-ray structures have been determined. The nmr spectra of 3-iodopyridine show that it contains phosphorus and nitrogen atoms. 3-Iodopyridine is also able to take up nitrate ions from solution, which may be due to its uptake properties., Application In Synthesis of 1120-90-7

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

In general, organic iodides are light-sensitive and turn yellow during storage, owing to the formation of iodine. 5029-67-4, formula is C5H4IN, Name is 2-Iodopyridine.Organic iodides can be alkyl, alkenyl, or alkynyl, and all of them are very reactive toward with many kinds of nucleophiles. HPLC of Formula: 5029-67-4.

Meng, Qi;Zhang, Lian;Zhu, Xinhui;Teng, Qiaoqiao research published 《 Synthesis of 9-O-Arylated Berberine with a Polystyrene Resin Supported Copper(II) Catalyst》, the research content is summarized as follows. A series of polyfluorobenzene, pyridine and aniline substituted berberine derivatives I (Ar = Ph, 4-H₂NC₆H₄, 3-pyridyl, etc.) were prepared via resin-supported Cu(II) catalyzed cross-coupling reactions of tetrahydroberberrubine with iodoarenes and subsequent I₂ oxidation The best catalyst, a polyethyleneimine functionalized polystyrene supported Cu²⁺ (PSAPA·Cu(II)), could be reused for at least 5 runs without significant loss of catalytic activity. Comparative studies on the morphol. and porous structures of the materials suggested a catalyst with a moderate sp. surface area and larger pore diameters was more active in catalyzing the cross-coupling reactions.

5029-67-4, 2-Iodopyridine can be synthesized from 2-chloropyridine or 2-bromopyridine via treatment with iodotrimethylsilane.
2-Iodopyridine, also known as 2-Iodopyridine, is a useful research compound. Its molecular formula is C5H4IN and its molecular weight is 205 g/mol. The purity is usually 95%.
2-Iodopyridine is a halogenated building block. It is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors
2-Iodopyridine is a white crystalline solid that is soluble in water, alcohol, and ether. The molecule contains a methyl group and two iodine atoms. 2-Iodopyridine has several industrial uses. It acts as a precursor to various pharmaceuticals and agrochemicals. The compound also exhibits insulin resistance properties, which may be related to its ability to bind to the insulin receptor and inhibit insulin signaling. 2-Iodopyridine can also be used for treating cancer because it binds to the DNA of cancer cells, preventing replication and leading to cell death.
2-Iodopyridine is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors., HPLC of Formula: 5029-67-4

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. 5029-67-4, formula is C5H4IN, Name is 2-Iodopyridine. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability. Recommanded Product: 2-Iodopyridine.

Mhaldar, Pradeep M.;Patil, Mayuri V.;Rashinkar, Gajanan S.;Pore, Dattaprasad M. research published 《 Magnetically Recoverable Palladium Nanocatalyst [Pd(II)-Benz-Am-Fe₃O₄@SiO₂] for Ullmann Type Homocoupling of Aryl halides with N₂H₄ as an Efficient Reductant》, the research content is summarized as follows. A highly efficient and sustainable ferrite supported palladium nanocatalyst (Pd(II)-Benz-Am-Fe₃O₄@SiO₂) has been prepared and characterized by diverse microscopic and spectroscopic techniques. The Pd(II)-Benz-Am-Fe₃O₄@SiO₂ was employed as magnetically recoverable nanocatalyst in the synthesis of sym. biaryls by reductive homocoupling of haloarenes (I, Br and Cl) using hydrazine hydrate (N₂H₄) as reducing agent. The Pd-Benz-Am-Fe₃O₄@SiO₂ nanocatalyst exhibited high surface area and efficient magnetization as 45.25 m²/g and 34 emu/g, resp. The Electron Dispersive X-ray (EDX) anal. confirmed 3.9 mol % loading of Pd in Pd-Benz-Am-Fe₃O₄@SiO₂. Moverever, high turnover number (TON) and turnover frequency (TOF), operational simplicity and facial recyclability and reusability (up to eight runs) are the remarkable advantages of the nanocatalyst. The catalytic activity and stability of recycled Pd(II)-Benz-Am-Fe₃O₄@SiO₂ catalyst was comprehensively studied from X-ray diffraction (XRD), SEM (SEM), Transmission Electron Microscopic (TEM) and EDX anal.

Recommanded Product: 2-Iodopyridine, 2-Iodopyridine can be synthesized from 2-chloropyridine or 2-bromopyridine via treatment with iodotrimethylsilane.
2-Iodopyridine, also known as 2-Iodopyridine, is a useful research compound. Its molecular formula is C5H4IN and its molecular weight is 205 g/mol. The purity is usually 95%.
2-Iodopyridine is a halogenated building block. It is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors
2-Iodopyridine is a white crystalline solid that is soluble in water, alcohol, and ether. The molecule contains a methyl group and two iodine atoms. 2-Iodopyridine has several industrial uses. It acts as a precursor to various pharmaceuticals and agrochemicals. The compound also exhibits insulin resistance properties, which may be related to its ability to bind to the insulin receptor and inhibit insulin signaling. 2-Iodopyridine can also be used for treating cancer because it binds to the DNA of cancer cells, preventing replication and leading to cell death.
2-Iodopyridine is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors., 5029-67-4.

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

Iodide is one of the largest monatomic anions. It is assigned a radius of around 206 picometers. 626-01-7, formula is C6H6IN, Name is 3-Iodoaniline.For comparison, the lighter halides are considerably smaller: bromide (196 pm), chloride (181 pm), and fluoride (133 pm). In part because of its size, iodide forms relatively weak bonds with most elements. Recommanded Product: 3-Iodoaniline.

Michalke, Jessica;Haas, Michael;Krisch, Dominik;Boegl, Thomas;Bartling, Stephan;Rockstroh, Nils;Schoefberger, Wolfgang;Topf, Christoph research published 《 Generation of Cobalt-Containing Nanoparticles on Carbon via Pyrolysis of a Cobalt Corrole and Its Application in the Hydrogenation of Nitroarenes》, the research content is summarized as follows. The manufacture of a state-of-the-art heterogeneous non-noble metal catalyst was reported, which was based on a molecularly well-defined phosphine-tagged cobalt corrole complex. This precursor compound was readily synthesized from convenient starting materials while the active material is obtained through wet-impregnation of the pertinent metalliferous macrocycle onto carbon black followed by controlled pyrolysis of the loaded carrier material under an inert gas atm. Thus, the obtained composite was then applied in the heterogeneous hydrogenation of various nitroarenes to yield a vast array of valuable aniline derivatives that were conveniently isolated as their hydrochloride salts. The introduced catalytic protocol was robust and user-friendly with the entire assembly of the reaction set-up enabling the conduction of the experiments on the laboratory bench without any protection from air.

626-01-7, 3-Iodoaniline is a useful research compound. Its molecular formula is C6H6IN and its molecular weight is 219.02 g/mol. The purity is usually 95%.

3-Iodoaniline is a fatty acid that is used in analytical methods to measure the concentration of human serum in blood. It can be used to estimate the population growth rate, with a half-life of about 13 hours. 3-Iodoaniline reacts with hydrogen bond and proton to form a reaction solution, which can be catalyzed by palladium-catalyzed coupling and suzuki coupling reactions. The activation energies for these reactions are typically in the range of 4-8 kcal/mol. The chemical ionization technique is a type of mass spectrometry that is used to determine kinetic data for this compound. Hydrochloric acid can be added as an acid catalyst to increase the rate of reaction and generate more accurate kinetic data., Recommanded Product: 3-Iodoaniline

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. 1120-90-7, formula is C5H4IN, Name is 3-Iodopyridine. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability. COA of Formula: C5H4IN.

Li, Zhaojie;Shen, Jie;Jiang, Qing;Shen, Sheng;Zhou, Jing;Zeng, Huaqiang research published 《 Directionally Aligned Crown Ethers as Superactive Organocatalysts for Transition-metal Ion-free Arylation of Unactivated Arenes》, the research content is summarized as follows. When one-dimensionally aligned to the same side, multiple non-covalently associated crown ether groups could act as a whole to yield a higher catalytic activity than an individual poorly active crown ether group, delivering the lowest catalyst loading of 1-2 mol among all hitherto known organocatalysts for catalyzing direct arylation of inactivated arenes such as benzene, 1,4-difluorobenzene, pyridine and pyrazine with iodoarenes ArI (Ar = Ph, naphthalen-2-yl, thiophen-3-yl, etc.).

COA of Formula: C5H4IN, 3-Iodopyridine is a heteroaryl halide. It undergoes microwave-assisted coupling with heterocyclic compounds (pyrazole, imidazole, pyrrole and indole) to afford the corresponding N-3-pyridinyl-substituted heterocyclic compounds.

3-Iodopyridine is a useful research chemical used as a reactant in the copper-catalyzed coupling of alkylamines and aryl iodides.

3-Iodopyridine is an isomeric compound that can be synthesized by cross-coupling reactions. This compound has been shown to have nicotinic acetylcholine receptor binding properties and may be useful in the treatment of Alzheimer’s disease. 3-Iodopyridine is a primary amino acid that can be used for the synthesis of amines, which are nitrogen nucleophiles. It has been crystallized with halides and its x-ray structures have been determined. The nmr spectra of 3-iodopyridine show that it contains phosphorus and nitrogen atoms. 3-Iodopyridine is also able to take up nitrate ions from solution, which may be due to its uptake properties., 1120-90-7.

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. 5029-67-4, formula is C5H4IN, Name is 2-Iodopyridine. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability. Recommanded Product: 2-Iodopyridine.

Li, Zhaojie;Shen, Jie;Jiang, Qing;Shen, Sheng;Zhou, Jing;Zeng, Huaqiang research published 《 Directionally Aligned Crown Ethers as Superactive Organocatalysts for Transition-metal Ion-free Arylation of Unactivated Arenes》, the research content is summarized as follows. When one-dimensionally aligned to the same side, multiple non-covalently associated crown ether groups could act as a whole to yield a higher catalytic activity than an individual poorly active crown ether group, delivering the lowest catalyst loading of 1-2 mol among all hitherto known organocatalysts for catalyzing direct arylation of inactivated arenes such as benzene, 1,4-difluorobenzene, pyridine and pyrazine with iodoarenes ArI (Ar = Ph, naphthalen-2-yl, thiophen-3-yl, etc.).

Recommanded Product: 2-Iodopyridine, 2-Iodopyridine can be synthesized from 2-chloropyridine or 2-bromopyridine via treatment with iodotrimethylsilane.
2-Iodopyridine, also known as 2-Iodopyridine, is a useful research compound. Its molecular formula is C5H4IN and its molecular weight is 205 g/mol. The purity is usually 95%.
2-Iodopyridine is a halogenated building block. It is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors
2-Iodopyridine is a white crystalline solid that is soluble in water, alcohol, and ether. The molecule contains a methyl group and two iodine atoms. 2-Iodopyridine has several industrial uses. It acts as a precursor to various pharmaceuticals and agrochemicals. The compound also exhibits insulin resistance properties, which may be related to its ability to bind to the insulin receptor and inhibit insulin signaling. 2-Iodopyridine can also be used for treating cancer because it binds to the DNA of cancer cells, preventing replication and leading to cell death.
2-Iodopyridine is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors., 5029-67-4.

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. 5029-67-4, formula is C5H4IN, Name is 2-Iodopyridine. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability. Product Details of C5H4IN.

Liedtke, Rene;Surmiak, Sabrina;Jie, Xiaoming;Daniliuc, Constantin G.;Kehr, Gerald;Erker, Gerhard research published 《 Ring Construction by 1,1-Carboboration; Making Anthracene Derivatives from a Tetra(alkynyl)benzene》, the research content is summarized as follows. 1,2,4,5-Tetrakis(trimethylsilylethynyl)benzene reacted with two molar equivalents of the boranes R-B(C₆F₅)₂ (R=C₆F₅, Me, Ph) in a series of sequential 1,1-carboboration reactions to give ca. 1 : 1 mixtures of the two-fold benzannulated products, namely the resp. C_2h and C_2v sym. tetra-silyl, bis-boryl substituted anthracenes. Their active B(C₆F₅)₂ substituents were used for consecutive Suzuki-Miyaura C-C coupling reactions to give boron-free Ph or 2-pyridyl substituted anthracene products.

Product Details of C5H4IN, 2-Iodopyridine can be synthesized from 2-chloropyridine or 2-bromopyridine via treatment with iodotrimethylsilane.
2-Iodopyridine, also known as 2-Iodopyridine, is a useful research compound. Its molecular formula is C5H4IN and its molecular weight is 205 g/mol. The purity is usually 95%.
2-Iodopyridine is a halogenated building block. It is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors
2-Iodopyridine is a white crystalline solid that is soluble in water, alcohol, and ether. The molecule contains a methyl group and two iodine atoms. 2-Iodopyridine has several industrial uses. It acts as a precursor to various pharmaceuticals and agrochemicals. The compound also exhibits insulin resistance properties, which may be related to its ability to bind to the insulin receptor and inhibit insulin signaling. 2-Iodopyridine can also be used for treating cancer because it binds to the DNA of cancer cells, preventing replication and leading to cell death.
2-Iodopyridine is a reagent used in the preparation of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase inhibitors., 5029-67-4.

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com

Alkyl iodides react at a faster rate than alkyl fluorides due to the weak C-I bond. Iodo alkanes participate in a variety of organic synthesis reactions, which include the Simmons-Smith reaction (cyclopropanation using iodomethane), 626-01-7, formula is C6H6IN, Name is 3-Iodoaniline. Williamson ether synthesis, Wittig reaction, Grignard reaction, alkyl coupling reactions, and Wurtz reaction. Recommanded Product: 3-Iodoaniline.

Lisboa, Lynn S.;Preston, Dan;McAdam, C. John;Wright, L. James;Hartinger, Christian G.;Crowley, James D. research published 《 Heterotrimetallic Double Cavity Cages: Syntheses and Selective Guest Binding》, the research content is summarized as follows. A strategy for the generation of heterotrimetallic double cavity (DC) cages [Pd_nPt_mL₄]⁶⁺ (DC1: n = 1, m = 2; and DC2: n = 2, m = 1) is reported. The DC cages were generated by combining an inert platinum(II) tetrapyridylaldehyde complex with a suitably substituted pyridylamine and Pd^II ions. ¹H and DOSY NMR spectroscopy (NMR) and electrospray ionization mass spectrometry (ESIMS) data were consistent with the formation of the DC architectures. DC1 and DC2 were shown to interact with several different guest mols. The structure of DC1, which features two identical cavities, binding two 2,6-diaminoanthraquinone (DAQ) guest mols. was determined by single-crystal x-ray crystallog. In addition, DC1 was shown to bind two mols. of 5-fluorouracil (5–FU) in a statistical (non-cooperative) manner. In contrast, DC2, which features two different cage cavities, was found to interact with two different guests, 5–FU and cisplatin, selectively.

Recommanded Product: 3-Iodoaniline, 3-Iodoaniline is a useful research compound. Its molecular formula is C6H6IN and its molecular weight is 219.02 g/mol. The purity is usually 95%.

3-Iodoaniline is a fatty acid that is used in analytical methods to measure the concentration of human serum in blood. It can be used to estimate the population growth rate, with a half-life of about 13 hours. 3-Iodoaniline reacts with hydrogen bond and proton to form a reaction solution, which can be catalyzed by palladium-catalyzed coupling and suzuki coupling reactions. The activation energies for these reactions are typically in the range of 4-8 kcal/mol. The chemical ionization technique is a type of mass spectrometry that is used to determine kinetic data for this compound. Hydrochloric acid can be added as an acid catalyst to increase the rate of reaction and generate more accurate kinetic data., 626-01-7.

Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com