НАФТАЛИН-1,5-ДИИЗОЦИАНАТ

Описание

Naphthalene diisocyanate (NDI) occurs as white to lightyellow crystalline flakes with a characteristic odor. NDI is incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions. NDI can react with water to form amines and liberate carbon dioxide.

Химические свойства

Naphthylene 1,5-diisocyanate is a solid, m.p. 128°C. It has a lower vapour pressure than tolylene diisocyanate and is therefore less toxic in use; it does, however, have sensitizing properties.

Использование

Manufacture of polyurethane solid elastomers.

Подготовка

Naphthylene 1,5-diisocyanate (NDI) is prepared from naphthalene as follows:

Общее описание

White to light-yellow crystalline flakes.

Профиль реактивности

Isocyanates and thioisocyanates, such as 1,5-Naphthalene diisocyanate, are incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions in these materials. Some isocyanates react with water to form amines and liberate carbon dioxide. Base-catalysed reactions of isocyanates with alcohols should be carried out in inert solvents. Such reactions in the absence of solvents often occur with explosive violence, [Wischmeyer(1969)].

Опасность

Irritant. Questionable carcinogen.

Профиль безопасности

A powerful allergen. An irritant. Questionable carcinogen. When heated to decomposition it emits toxic fumes of NOx.

Экологическая судьба

NDI is a synthetic organic chemical. It is a natural derivative of primary amines with the general formula R–N]C]O which does not occur naturally in the environment. At room temperature it can be a liquid or crystal. It is miscible with alcohol, diglycol, monoethyl ether, ether, acetone, carbon tetrachloride, benzene, chlorobenzene, kerosene, and olive oil; however, it may react violently with alcohol, water, acid, bases, and strong alkaline materials and tertiary amines and generate enough heat to self-ignite and release toxic combustion products. NDI is not readily biodegradable; however, it reacts with water and most acids producing unstable carbonic acids, which subsequently decarboxylate yielding relatively chemically inert and insoluble polymeric urea. While these polyureas are persistent, studies have indicated that they pose virtually no potential for adverse impacts on the aquatic environment. Due to hydrolysis in water, bioaccumulation of NDI is not expected. Since the hydrolysis products formed are irritants, there is a potential for inhalation exposure. The degree stability is a function of humidity.