Hydroxyurethanes

Benzaldehyde can be condensed with the N-silylated urethane 671 and aUyltri-methylsilane 82 in the presence of trityl perchlorate to give, via an intermediate 0,N-acetal, the substituted urethane 672 in high yield [197]. 0,N-Acetals such as 673 condense with the enol silyl ether of acetophenone 653 in the presence of TMSOTf 20 to give the co-hydroxyurethane 674 in 94% yield [198] (Scheme 5.62). 

Urethane can be excreted in the urine unchanged (0.5-1.7% of dose). Urethane can also be metabolized by the liver cytochrome P450 system. The urinary metabolites of urethane include N-hydroxy urethane, acetyl-N-hydroxyurethane, ethyl mercapt-uric acid, and N-acetyl-S-ethoxycarbonyl cysteine. 

STRUCTURE 4.1 Hydrogen bonding in a hydroxyurethane. (Reprinted from E. Delebecq, J-P. Pascault, B. Boutevin, and F. Ganachaud, On the Versatility of Urethane/Urea Bonds Reversibility, Blocked Isocyanate, and Non-Isocyanate Polyurethane, Chem. Rev. 113 (2013) 80-118. With permission.)... 

A novel concept for generating new multifunctional modifiers was developed [26], Hydroxyurethane modifiers (HUMs), which possess a wide range of hydrogen bonds, are embedded in an epoxy polymer network without a direct chemical interaction. Some new hybrid materials obtained by introducing hydroxyalkyl urethane into the polymer network structure, without any additional chemical reactions, are described in the following sections. 

SCHEME 4.5 The process of HUM preparation. (Reprinted from O. Figovsky, O. Birukov, L. Shapovalov, and A. Leykin, Hydroxyurethane Modifier as Effective Additive for Epoxy Matrix, Scientific Israel Technological Advantages 13, no. 4 (2011) 122-128. With permission.)... 

Hydroxyurethane Compounds from Renewable Plant-Based Raw Materials... 

The company Polymate Ltd-INRC (Israel) has developed a number of new two-component flooring and coating compositions based on hybrid nonisocyanate polyurethanes using hydroxyurethane modifiers. Properties of the new materials are presented in Table 4.16 [5,37,38],... 

Figovsky, O., Shapovalov, L., Blank, N., and Buslov, F. Method of Synthesis of Polyfunctional Hydroxyurethane Oligomers and Hybrid Polymers Formed Therefrom . EP Patent 1070733, Issued January 24, 2001. 

Novel hydroxyurethane modifiers (HUM) for cold-cured epoxy composite materials were synthesized. It is established that the compositions with HUM demonstrate a significant increase in the speed of the curing process, a nontrivial increase in abrasion resistance, and a marked improvement in strength properties. The HUM, which possesses a wide range of hydrogen bonds, is embedded in an epoxy polymer network without a direct chemical interaction. 

King prepared TV-ethoxycarbonylisoxazolidine by the base-catalyzed condensation of 1,3-dibromopropane with /V-hydroxyurethane, which was decarbethoxylated by hydrochloric acid to give the parent isoxazo-licjine (l).5 If 1,3-dibromopropane is treated with potassium benzo-hydroxamate, /V benzoylisoxazolidine is obtained.149... 

---