24731-90-6

Upstream product

• 67-63-0 isopropyl alcohol 
• 101-68-8 di(4-isocyanatophenyl)methane 

Downstream Products

• 101-68-8 di(4-isocyanatophenyl)methane 

Relevant academic research and scientific papers

Fluoride-Catalyzed Deblocking: A Route to Polymeric Urethanes

We report a fluoride-catalyzed deblocking of urethanes as “blocked” isocyanates. Organic and inorganic sources of fluoride ion proved effective for deblocking urethanes and for converting polyurethanes to small molecules. Distinct from conventional deblocking chemistry involving organometallic compounds and high temperatures, the method we describe is metal-free and operates at or slightly above room temperature. The use of fluorescent blocking agents enabled visual and spectroscopic monitoring of blocking/deblocking reactions, and the selected conditions proved applicable to urethanes containing a variety of blocking groups. The method additionally enabled a one pot deblocking and polymerization with α,ω-diols. Overall, this deblocking/polymerization strategy offers a convenient and efficient solution to problems that have limited the breadth of applications of polyurethane chemistry.

Thermoreversible crosslinking of polyethylene enabled by free radical initiated functionalization with urethane nitroxyls

This paper describes the functionalization of polyethylene with urethane derivatives of 2,2,6,6-tetramethylpiperidinyloxy (TEMPO), resulting in thermoreversible crosslinking of the polymer, which exhibits thermoplastic characteristics at sufficiently elevated temperatures. The urethane TEMPO adducts were synthesized by the reaction of 4-hydroxy TEMPO with various diisocyanates using appropriate catalysts, and were subsequently grafted to polyethylene using free-radical chemistry. A model study conducted on urethane isopropanol adducts confirmed that endothermic urethane reversion occurred with aromatic and alkyl diisocyanates at temperatures greater than 170 °C, and no exothermic urethane decomposition was observed. In contrast, urethane TEMPO adducts underwent exothermic decomposition at elevated temperatures, probably because of participation of the free nitroxyl species in urethane decomposition. Hence, the urethane TEMPO adducts were most effective when used as crosslinkers below their decomposition points.

Novel material forming supramolecular structures, process and uses

The invention relates to novel material, forming supramolecular structures below its transition temperature, which contains at least one C=O and/or C=S group and at least one N—H, O—H and/or S—H group and wherein the material has the structure [in-line-formulae]A(—X—B)n ??(1)[/in-line-formulae] wherein A is a cyclic, aromatic and/or aliphatic group, n being a number of 1 to 4, —X—B is, if n is 2, the same or different, and if n is 3 or 4, the same, partly the same or different and has one of the structures (2) to (4) [in-line-formulae]NH—C(Y)—Y—B ??(2)[/in-line-formulae] [in-line-formulae]—NH—C(Y)—NR—B ??(3)[/in-line-formulae] [in-line-formulae]—Y—C(Y)—NR—B ??(4)[/in-line-formulae] with Y being an Oxygen and/or Sulfur atom, B being an organic group with at least one heteroatom, where the heteroatom is bound to at least two carbon atoms when B is linear or cyclic, and where the heteroatom is bound to at least one carbon atom when B is branched, and R being a Hydrogen atom, a cyclic, aromatic and/or aliphatic group or another B group which is the same or different. The material can be made by reacting at least one isocyanate and/or thioisocyanate with at least one amine, alcohol and/or thiol. Typically, the material is used first below its transition temperature, followed by increasing the temperature to around or above the transition temperature, carrying out a process step and subsequently decrease the temperature below the transition temperature.

Process for the preparation of N,O-disubstituted urethanes suitable as a starting material for the preparation of isocyanates

A process for the preparation of N,O-disubstituted urethanes. Primary amines and alcohols are reacted with organic compounds having carbonyl groups at 120° to 350° C. Suitable carbonyl-containing compounds include N-unsubstituted urethanes. N-mono-substituted, N,N'-disubstituted ureas, or polyureas may be used in combination with the N-unsubstituted urethane. The product urethanes are particularly suitable for the preparation of isocyanates.

HYDROGENATION OF N-ARYL CARBAMATES TO N-ALICYCLIC CARBAMATES.

An economical, high-yield process is developed for the preparation of pure N-alicyclic carbamates by the rhodium-catalyzed hydrogenation of the corresponding N-aryl carbamates. The N-aryl carbamates are obtained by the simple reaction of low-cost aromatic