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The yellow complex Rh(PPh 3) 3 (NCO) and orange complex Rh(PPh 3) 3 (OCN) are linkage isomers and show differences in their infrared spectra which can be used for diagnosis. [15] The cyanate ion can bridge between two metal atoms by using both its donor atoms. For example, this structure is found in the compound [Ni 2 (NCO) 2 2](BPh 4) 2. In ...
2OC(NH 2) 2 + Na 2 CO 3 → 2Na(NCO) + CO 2 + 2NH 3 + H 2 O. Sodium allophanate is observed as an intermediate: [2] H 2 NC(O)NHCO 2 Na → NaOCN + NH 3 + CO 2. It can also be prepared in the laboratory by oxidation of a cyanide in aqueous solution by a mild oxidizing agent such as lead oxide. [3]
Biological tests exist to identify isocyanate exposure; [51] the US Navy uses regular pulmonary function testing and screening questionnaires. [ 52 ] Emergency management is a complex process of preparation and should be considered in a setting where a release of bulk chemicals may threaten the well-being of the public.
Blocked isocyanates are particularly useful in products with a dual cure mechanisms. As an example, Ultraviolet light initiates the polymerization of an acrylate based polymer that contains hydroxy groups on the polymer backbone. The system would also contain an isocyanate blocked with a malonate. This is now a one-component system.
A range of NCO/OH eq. ratios from 1.2 - 1.6 was used. Thermal and mechanical properties of moisture cured polyurethane-urea /clay nanocomposite coatings have been studied in relationship to clay dispersion and intercalation of clay platelets in the urethane-urea matrix. [ 4 ]
Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to a single oxygen atom (i.e. H 2 O). The atomic ratio of hydrogen to oxygen is always 2:1 in every molecule of water. Pure water will tend to boil near 100 °C
Where HV is the hydroxyl value; V B is the amount (ml) potassium hydroxide solution required for the titration of the blank; V acet is the amount (ml) of potassium hydroxide solution required for the titration of the acetylated sample; W acet is the weight of the sample (in grams) used for acetylation; N is the normality of the titrant; 56.1 is ...
Non-stoichiometric compounds are chemical compounds, almost always solid inorganic compounds, having elemental composition whose proportions cannot be represented by a ratio of small natural numbers (i.e. an empirical formula); most often, in such materials, some small percentage of atoms are missing or too many atoms are packed into an ...