• One of at least two aromatic isocyanate functional groups rapidly hydrolyses by dissolved water with the formation of inert polyurea. (europa.eu)
  • All substances of the MDI category possess aromatic isocyanate functional groups which are known to rapidly hydrolyse and polymerise to polyurea when added to water. (europa.eu)
  • Curtius rearrangement degradation of an acyl azide to an isocyanate and nitrogen gas. (wikipedia.org)
  • Rearrangement of the acyl azide to an isocyanate through migration of the R group. (scivus.com)
  • For repeating units of polymers , functional groups attach to their nonpolar core of carbon atoms and thus add chemical character to carbon chains. (wikipedia.org)
  • Novel nano-cellulose based nano-structures modified with hyper-branched polymers were prepared by using isocyanate linking chemistry. (4spe.org)
  • In the case of polymers, the functional groups are generally attached to the nonpolar core of the carbon atoms in each repeating unit of the corresponding polymer, infusing the carbon chain with specific chemical characteristics. (byjus.com)
  • The diisocyanate monomers are important commercially the most important aromatic isocyanates, because the two NCO groups allow them to undergo direct whereas 1,6-HDI, isophorone diisocyanate (IPDI), methyle- polymerization reactions with alcohols to form polyur- nedicyclohexyl diisocyanate (HMDI), and their higher ethanes, in addition to enabling prepolymerization reactions polymers are the most important aliphatic isocyanates. (cdc.gov)
  • Polyester is a category of polymers that contain the ester functional group in their main chain. (maindifference.net)
  • N-[3-(Trimethoxysilyl)propyl]aniline(CAS:3068-76-6), Our model SCA-A69M (equivalent to Silquest® Y-9669 ),is a versatile amino functional coupling agents used over a broad range of applications to provide superior bonds between inorganic substrates and organic polymers. (capatuechem.com)
  • As a consequence of the chemical reactivity of the common aromatic isocyanate (NCO) functional group present on all substances of the MDI category and the high reactivity of this group with water, hydrolysis is the determinant of the fate of MDI substances in the environment. (europa.eu)
  • In this category, Substances of the MDI category all share similar chemical features namely that they a) all contain high levels of mMDI, and b) contain have at least two aromatic NCO groups that are electronically separated from other aromatic rings by at least a methylene bridge. (europa.eu)
  • 2003). Due to the common reactivity of the isocyanate group and the relatively similar rate constants for the two substances, it is expected that substances of the MDI category will react similarly. (europa.eu)
  • Three rearrangement reactions involving nitrenes give isocyanates: Schmidt reaction, a reaction where a carboxylic acid is treated with ammonia and hydrazoic acid yielding an isocyanate. (wikipedia.org)
  • R2NC(O)NR'C(O)NHR''}}} Reaction between a di-isocyanate and a compound containing two or more amine groups produces long polymer chains known as polyureas. (wikipedia.org)
  • Isocyanates are common intermediates in the synthesis of primary amines via hydrolysis: Hofmann rearrangement, a reaction in which a primary amide is treated with a strong oxidizer such as sodium hypobromite or lead tetraacetate to form an isocyanate intermediate. (wikipedia.org)
  • The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of. (newworldencyclopedia.org)
  • HDI, particularly those such as hydrolysis, which involve reaction with active hydrogen compounds and addition to the carbon-nitrogen double bond of the highly reactive isocyanate group. (cdc.gov)
  • OECD 120), reaction of the NCO group with water occurs rapidly at the boundary layer of the MDI substances droplet and by water diffusing onto and into the organic phase forming inert polyurea p articles. (europa.eu)
  • In this one-step process, polyurethane was formed by the reaction of the isocyanates with the hydroxyl-functional groups from the polyester, while its gas phase was formed by the generation of carbon dioxide. (iqsdirectory.com)
  • Each chapter deals with the preparation of a given functional group by various reaction types (condensation, elimination, oxidation, reduction) and a variety of starting materials. (elsevier.com)
  • The manner in which the functional groups indulge in a chemical reaction can be further modified with the help of other functional groups, and these groups can also be interconverted. (byjus.com)
  • At room temperature reaction with for instance isocyanates is possible. (stackexchange.com)
  • The epoxy group is very reactive, reaction enthalpy is around 96 kJ/mol typically, with many chemical species. (stackexchange.com)
  • Use of differential reaction rates to analyze mixtures containing the same functional group / 26. (itech.fr)
  • To simultaneously form films while synthesizing solvent-free and catalyst-free bio-based polyurethanes, hexamethylene diisocyanate trimer was selected as an isocyanate group source to produce a low-viscosity reaction medium for dispersing high contents of microcrystalline cellulose (MCC, polyol) and cellulose nanocrystals (CNC). (bvsalud.org)
  • 0011] It is essential that the intermediate layer (ii) is formed of the aqueous urethane resin composition (C) containing the urethane resin (A) and the aqueous medium (B), and the urethane resin (A) is a reaction product of the polyol (a1) containing the polyol (a1-1) having an anionic group and the aromatic polyisocyanate (a2), and has an anionic group in a concentration of 0.35 mmol/g or less. (epo.org)
  • The BioPU coatings were analyzed in terms of chemical structure, the extent of the reaction of the isocyanate species, thermal stability, hydrophobicity, and adhesion strength. (dntb.gov.ua)
  • Insight into the mechanism of aryl isocyanate formation was gleaned through studies of the transmetalation and reductive elimination steps of the reaction, including the first demonstration of reductive elimination from an arylpalladium isocyanate complex to produce an aryl isocyanate. (mit.edu)
  • The Curtius rearrangement, named after the German chemist Theodor Curtius, is a chemical reaction that involves the conversion of a carboxylic acid into an isocyanate compound. (scivus.com)
  • The migration of nitrogen is a key feature of this reaction, leading to the transformation of the acyl azide into an isocyanate. (scivus.com)
  • The reaction typically proceeds via the formation of an isocyanate intermediate. (scivus.com)
  • A monofunctional isocyanate of industrial significance is methyl isocyanate (MIC), which is used in the manufacture of pesticides. (wikipedia.org)
  • Isocyanates are electrophiles, and as such they are reactive toward a variety of nucleophiles including alcohols, amines, and even water having a higher reactivity compared to structurally analogous isothiocyanates. (wikipedia.org)
  • The reactivity of a functional group can be modified by other functional groups nearby. (wikipedia.org)
  • Interestingly, the presence of an amine group strongly increases the reactivity of the aromatic ring, due to an electron-donating effect. (newworldencyclopedia.org)
  • It is the NCO value (driven by the bioaccessible NCO groups on relatively soluble mMDI and low molecular weight species ( e.g. three-ring oligomer) which is responsible for chemical and physiological reactivity and subsequent toxicological profile. (europa.eu)
  • Recent studies have focused on asymmetric synthesis of structurally complex amino acids, using what has proved to be a very versatile radical-based methodology and also the use of structurally unusual heterocycles for masking the reactivity of synthetically valuable functional groups. (exeter.ac.uk)
  • The reactivity of these groups varies due to the nature of the carbon-carbon bond . (byjus.com)
  • Dabco NE500 catalyst is a non-emissive tertiary amine used as a catalyst for polyurethane block sponges to promote urethane reactions.Dabco NE500 catalyst has reactive functional groups that react with the polyurethane matrix and therefore do not cause emissions. (dpta.vip)
  • Complementarily, alkyl isocyanates form by displacement reactions involving alkyl halides and alkali metal cyanates. (wikipedia.org)
  • Isocyanates participate in Diels-Alder reactions, functioning as dienophiles. (wikipedia.org)
  • In organic chemistry , a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions . (wikipedia.org)
  • The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. (wikipedia.org)
  • In organic chemistry , functional groups (or moieties) are specific groups of atoms within molecules , that are responsible for the characteristic chemical reactions of those molecules. (newworldencyclopedia.org)
  • Functional groups are far less stable than the carbon backbone and are likely to participate in chemical reactions. (newworldencyclopedia.org)
  • Using this catalyst, the team performed hydroboration reactions of seven carbodiimides and nine isocyanates with pinacolborane at room temperature. (chemistryviews.org)
  • The book puts special attention to the presentation of specific laboratory directions for the many name reactions used in describing the synthesis of these functional groups. (elsevier.com)
  • Miscellaneous Reactions of Isocyanates and Alcohols 4. (elsevier.com)
  • A functional group is a group of atoms or bonds inside a substance that is responsible for the substance's unique chemical reactions in organic chemistry. (byjus.com)
  • Regardless of the chemical in which it is found, the same functional group will behave similarly and experience comparable reactions. (byjus.com)
  • Two molecules having different sizes but the same functional groups will take part in chemical reactions that are similar or exactly the same. (byjus.com)
  • The process of chemical synthesis, in which chemical reactions are intentionally executed in order to obtain a specific compound, can be designed by understanding the properties of various functional groups. (byjus.com)
  • Dabco NE500 is a non-emitting amine catalyst used to promote urea (water-isocyanate) reactions. (dpta.vip)
  • Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. (newworldencyclopedia.org)
  • Structurally amines resemble ammonia , wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups. (newworldencyclopedia.org)
  • An important exception to this rule is that compounds of the type RC(O)NR 2 , where the C(O) refers to a carbonyl group, are called amides rather than amines. (newworldencyclopedia.org)
  • Somewhat confusing is the fact that amines in which an N-H group has been replaced by an N-M group (M = metal) are also called amides. (newworldencyclopedia.org)
  • Higher amines have the prefix amino as a functional group. (newworldencyclopedia.org)
  • Alcohols, or alkanols, resemble amines but feature an -OH group in place of NR 2 . (newworldencyclopedia.org)
  • Amines contain the also nucleophilic $\ce{-NH2}$ group. (stackexchange.com)
  • Tertiary, allylic, amines nucleophilically add to the carbon of a heterocumulene (isocyanate, isothiocyanate, or carbodiimide) to generate a zwitterion which then undergoes [3,3]-sigmatropic rearrangement. (uvm.edu)
  • This step is pivotal in the conversion of the isocyanate into a carbamate, a key structural feature in the formation of primary amines. (scivus.com)
  • In phenyl isocyanate, the C=N and C=O distances are respectively 1.195 and 1.173 Å. (wikipedia.org)
  • Further refining of blowing agents, polyether polyols, and polymeric isocyanates led to the advancement from flexible polyurethane foams to rigid polyurethane foams. (iqsdirectory.com)
  • CR91410 is a polyurethane acrylate resin containing two functional groups of acryloyl and isocyanate groups, which can achieve dual curing of free radical curing and moisture curing.It is suitable for electronic circuit protection, special-shaped parts protection applications. (haohuimaterials.com)
  • The biopolyols obtained were successfully employed as a green raw material to produce bio-based polyurethane (BioPU) coatings on carbon steel substrates, using, as an isocyanate source, a commercial bio-based polyisocyanate-Desmodur® Eco N7300. (dntb.gov.ua)
  • Similarly, an organic compound with multiple amino groups is called a diamine , triamine , tetraamine and so forth. (newworldencyclopedia.org)
  • Amino groups / 12. (itech.fr)
  • It is a versatile adhesion promoter, particularly for resin systems that will react with a secondary amino group, such as isocyanates, acrylates, expoxies, phenolics and RTV silicones. (capatuechem.com)
  • Acrylic resins can also be thermally cured if they have functional groups, such as hydroxymethyl groups, or they are crosslinked with substances such as epoxy resins, (poly)isocyanates or amino resins. (terchemicals.com)
  • Isocyanates are highly reactive chemicals of low- products of even greater complexity. (cdc.gov)
  • ROC(O)N(H)R'}}} where R and R' are alkyl or aryl groups. (wikipedia.org)
  • C6H11N)2C + CO2}}} Isocyanates also can react with themselves. (wikipedia.org)
  • The hydroxyl-groups may react with phenol-/urea-/melamine-formaldehyde resins at elevated temperatures. (stackexchange.com)
  • The isocyanate can further react with various nucleophiles to form a wide range of compounds. (scivus.com)
  • Considering the polymeric epoxy backbone, two functional groups can be distinguished that are chemically active. (stackexchange.com)
  • In this area, we have developed a methodology for the incorporation of protected isocyanates into organic molecules and this chemistry is being applied to the synthesis of a diverse set of biologically important, nitrogen-containing heterocycles. (exeter.ac.uk)
  • Some more functional groups containing elements such as nitrogen and oxygen featuring different hybridizations of the carbon-nitrogen and the carbon-oxygen bonds are illustrated below. (byjus.com)
  • An epoxy group reacts with ONE amine-hydrogen, i.e. one hydrogen attached directly to a Nitrogen atom (hence also amine-hydrogen equivalent weight). (stackexchange.com)
  • This rearrangement is initiated by thermal or catalytic activation, which induces the migration of a nitrogen atom from the azide group to the adjacent carbon atom, causing the formation of an isocyanate intermediate. (scivus.com)
  • This rearrangement involves the migration of an oxygen atom from the carbonyl oxygen of the isocyanate group to the adjacent nitrogen atom. (scivus.com)
  • Aliphatic diisocyanates can trimerise to from substituted isocyanuric acid groups. (wikipedia.org)
  • Isocyanates are classified based on the number of N=C=O more aromatic rings) or saturated (aliphatic and alicyclic), groups in the molecule into monoisocyanates (one NCO), the term aliphatic isocyanate referring to saturated isocya- diisocyanate monomers (two NCO), or polyisocyanates nates. (cdc.gov)
  • They exhibit phenolic and aliphatic moieties displaying hydroxyl (OH) functional groups, as confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. (dntb.gov.ua)
  • An organic compound with two isocyanate groups is known as a diisocyanate. (wikipedia.org)
  • If a diisocyanate is treated with a compound containing two or more hydroxyl groups, such as a diol or a polyol, polymer chains are formed, which are known as polyurethanes. (wikipedia.org)
  • The isocyanate-free polyurethanes were based on polyhydroxyurethanes (PHUs) prepared from depolymerized native lignin, which we refer to as lignin hydrogenolysis oil (LHO). (bvsalud.org)
  • If there is another functional group at a carbon, it may be named with the Greek letter, e.g., the gamma-amine in gamma-aminobutyric acid is on the third carbon of the carbon chain attached to the carboxylic acid group. (wikipedia.org)
  • Do these contain both thiol and amine functional groups? (stackexchange.com)
  • At room temperature however by far the largest groups of chemicals used are amine-functional curing agents capable of cross linking epoxy resins at room temperature. (stackexchange.com)
  • The electrophilic species involved are isocyanate cation and acylium cation, respectively, and both have a common +C=O structure, which can be generated from carboxylic acid functionalities in a strong Brønsted acid. (bvsalud.org)
  • In organic chemistry, isocyanate is the functional group with the formula R−N=C=O. Organic compounds that contain an isocyanate group are referred to as isocyanates. (wikipedia.org)
  • Isocyanates should not be confused with cyanate esters and isocyanides, very different families of compounds. (wikipedia.org)
  • Combining the names of functional groups with the names of the parent alkanes generates what is termed a systematic nomenclature for naming organic compounds . (wikipedia.org)
  • Reducing carbodiimides (RN=C=NR) and isocyanates (RN=C=O) is an appealing route to formamidine and formamide functional groups, which appear, for example, in biologically active compounds. (chemistryviews.org)
  • Ynamines, enamines, allenes, and N-nitroso compounds are some of the organic functional groups described in the text. (elsevier.com)
  • The role of quantitative functional group determination in the identification of organic compounds / 25. (itech.fr)
  • O. Maduka Ogba, Allegra L. Liberman-Martin, Chapman University, Orange, CA, USA, and colleagues have developed a method for the selective hydroboration of carbodiimide and isocyanate substrates (pictured above) using Lewis-basic carbon catalysts. (chemistryviews.org)
  • The foam is made from an aromatic polyester compound and contains a short-chain structure, a long-chain structure, and a residual functional group of a chain extender. (just-style.com)
  • The OH group is reacted with an Isocyanate functional compound in a 2 component system producing coatings which may optionally be pigmented. (maindifference.net)
  • The term exp- assessment of isocyanate exposure for epidemiological osure metric has a broad meaning and can include a number research, clinical studies, and the development of isocyanate of parameters such as sampling strategy (species measured, units of measurement, sampling type and duration), analy- tical methodology (accuracy and precision), and the 1Work Environment Department, University of Massachusetts Lowell, Lowell, Massachu- relevance to health effects of interest. (cdc.gov)
  • The second major area of my group's research has involved studies into the use of structurally 'unusual' heterocycles as protected, reactive functional groups in organic synthesis. (exeter.ac.uk)
  • In terms of bonding, isocyanates are closely related to carbon dioxide (CO2) and carbodiimides (C(NR)2). (wikipedia.org)
  • Hydrocarbons are a class of molecule that is defined by functional groups called hydrocarbyls that contain only carbon and hydrogen, but vary in the number and order of double bonds. (wikipedia.org)
  • Functional groups are attached to the carbon backbone of organic molecules. (newworldencyclopedia.org)
  • A few functional groups involving carbon are illustrated below. (byjus.com)
  • Alkanes, alkenes, and alkynes (and sometimes the derivatives of benzene) are represented by the symbol R. these groups are also referred to as hydrocarbyl groups since they contain only carbon and hydrogen atoms. (byjus.com)
  • Plus, when functional groups are more electronegative than atoms they attach to, the functional groups will become polar, and the otherwise nonpolar molecules containing these functional groups become polar and so become soluble in some aqueous environment. (wikipedia.org)
  • In particular, we have developed methods for the stereoselective incorporation of the 1,2,4-dithiazolidine-3,5-dione (Dts imide) moiety into molecules as a masked isocyanate equivalent. (exeter.ac.uk)
  • When these groups are attached to molecules, they convert the molecule into either complexions or polyatomic ions. (byjus.com)
  • The cyanate (cyanate ester) functional group (R−O−C≡N) is arranged differently from the isocyanate group (R−N=C=O). Isocyanides have the connectivity R−N≡C, lacking the oxygen of the cyanate groups. (wikipedia.org)
  • Epoxides groups (oxirane oxygen) / 6. (itech.fr)
  • Lossen rearrangement, the conversion of a hydroxamic acid to an isocyanate via the formation of an O-acyl, sulfonyl, or phosphoryl intermediate. (wikipedia.org)
  • The 1,3-diaza Claisen rearrangement was initially discovered by the Madalengoitia group in the early 2000s. (uvm.edu)
  • The isocyanate intermediate undergoes a subsequent rearrangement, resulting in the formation of a carbamate intermediate. (scivus.com)
  • The following is a list of common functional groups. (wikipedia.org)
  • The common functional groups, along with the prefix and the suffix which must be used in their nomenclature is provided in this subsection. (byjus.com)
  • Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis . (wikipedia.org)
  • The protocol allows for the synthesis of unsymmetrical N,N'-di- and N,N,N'-trisubstituted ureas in one pot and is tolerant of a wide range of functional groups. (mit.edu)
  • A functional group is a group of atoms in a molecule with distinctive chemical properties , regardless of the other atoms in the molecule. (wikipedia.org)
  • The atoms in a functional group are linked to each other and to the rest of the molecule by covalent bonds . (wikipedia.org)
  • Functional groups can also be charged , e.g. in carboxylate salts (-COO − ), which turns the molecule into a polyatomic ion or a complex ion . (wikipedia.org)
  • However, a moiety is an entire "half" of a molecule, which can be not only a single functional group, but also a larger unit consisting of multiple functional groups. (wikipedia.org)
  • The non- hydrogen atoms of functional groups are always associated with each other and with the rest of the molecule by covalent bonds . (newworldencyclopedia.org)
  • When the group of atoms is associated with the rest of the molecule primarily by ionic forces, the group is referred to more properly as a polyatomic ion or complex ion-all of these are called radicals , by a meaning of the term radical that predates the free radical . (newworldencyclopedia.org)
  • Therefore, it can be understood that functional groups are the moieties which exhibit their own distinct features and properties independent of the molecule they are attached to. (byjus.com)
  • Covalent bonding links the atoms of these groups and the group as a whole to the molecule. (byjus.com)
  • The presence of functional groups in a molecule also affects the solubility and the tendency to form complexes of the molecule in question. (byjus.com)
  • In the scenario wherein a highly electronegative functional group is attached to a less electronegative atom or molecule, a polarity arises which enables the initially nonpolar molecule to be soluble in water or other aqueous environments. (byjus.com)
  • When the group of atoms is associated with the rest of the molecule primarily by ionic forces, the group is referred to more properly as a polyatomic ion or complex ion . (wikidoc.org)
  • According to the team, the work represents the first report of carbodiimide or isocyanate reduction catalyzed by a neutral, Lewis-basic organocatalyst. (chemistryviews.org)
  • the $\ce{-SH}$ group is likely strongly nucleophilic (to better pop open the epoxide rings). (stackexchange.com)
  • The foam also contains a residual functional group of a chain extender, which can be an epoxy group, isocyanate group, methylol group, imino group, or a combination thereof. (just-style.com)
  • Imino groups / 13. (itech.fr)
  • To sum up, the cross-linking modification of hydrophilic isocyanate can significantly improve the mechanical properties, flame retardancy, and hydrolysis resistance of KGM aerogels. (bvsalud.org)
  • As confirmed by Fourier transform infrared and scanning electron microscopy analysis, such improvement in mechanical properties can be attributed to the establishment of hydrogen bonds and other molecular interactions between isocyanate groups of PEG-HMDI prepolymer and hydroxyl groups of DCB biofiller along with the uniform distribution of the incorporated DCB into the PU-PEG based matrix. (kribb.re.kr)
  • Benzyl acetate has an ester functional group (in red), an acetyl functional group (circled with dark green) and a benzyloxy functional group (circled with light orange). (wikipedia.org)
  • Although NCO groups are present on the higher molecular weight constituents, they do not contribute to the toxicity profile because they are hindered due to their increased size and hydrophobicity. (europa.eu)
  • molecular weight containing the functional group -N=C=O. (cdc.gov)
  • The conceptual basis for control banding is a framework for the grouping of chemical exposures according to similar physical and chemical characteristics, intended processes/handling, and anticipated exposure scenarios (amount of chemical used and how workers would be exposed). (cdc.gov)
  • Background Determination of polyisocyanates is important because they are a major contributor of exposure to the isocyanate functional group in many workplace environments and are capable of inducing sensitization and asthma. (cdc.gov)
  • However, with multiple different measurement metrics in use, comparison of isocyanate exposure data between studies and development of occupational exposure limits (OELs) for polyisocyanates is difficult. (cdc.gov)
  • Results This analysis supports a need for standardization of isocyanate measurement metrics and provides a framework for the development of an OEL for polyisocyanates. (cdc.gov)
  • [3] In the formulas, the symbols R and R' usually denote an attached hydrogen, or a hydrocarbon side chain of any length, but may sometimes refer to any group of atoms. (wikipedia.org)
  • A bearing material may include a polyamide-imide polymer material and a difunctional crosslinking agent comprising a hydrocarbon chain and two functional groups. (justia.com)
  • The hydrocarbon functional groups may have an ionic charge on them. (byjus.com)
  • In response to an employee request, the development of occupational asthma secondary to exposure to isocyanate s was investigated at Trus Joist MacMillan (SIC-2493), Deerwood, Minnesota. (cdc.gov)
  • The authors conclude that a health hazard existed from exposure to isocyanate s. (cdc.gov)