Formaldehyde vapor, reaction with

Reactions with Ammonia and Amines. Acetaldehyde readily adds ammonia to form acetaldehyde—ammonia. Diethyl amine [109-87-7] is obtained when acetaldehyde is added to a saturated aqueous or alcohoHc solution of ammonia and the mixture is heated to 50—75°C in the presence of a nickel catalyst and hydrogen at 1.2 MPa (12 atm). Pyridine [110-86-1] and pyridine derivatives are made from paraldehyde and aqueous ammonia in the presence of a catalyst at elevated temperatures (62) acetaldehyde may also be used but the yields of pyridine are generally lower than when paraldehyde is the starting material. The vapor-phase reaction of formaldehyde, acetaldehyde, and ammonia at 360°C over oxide catalyst was studied a 49% yield of pyridine and picolines was obtained using an activated siHca—alumina catalyst (63). Brown polymers result when acetaldehyde reacts with ammonia or amines at a pH of 6—7 and temperature of 3—25°C (64). Primary amines and acetaldehyde condense to give Schiff bases CH2CH=NR. The Schiff base reverts to the starting materials in the presence of acids. 

Formaldehyde condenses with itself in an aldol-type reaction to yield lower hydroxy aldehydes, hydroxy ketones, and other hydroxy compounds the reaction is autocatalytic and is favored by alkaline conditions. Condensation with various compounds gives methylol (—CH2OH) and methylene (=CH2) derivatives. The former are usually produced under alkaline or neutral conditions, the latter under acidic conditions or in the vapor phase. In the presence of alkahes, aldehydes and ketones containing a-hydrogen atoms undergo aldol reactions with formaldehyde to form mono- and polymethylol derivatives. Acetaldehyde and 4 moles of formaldehyde give pentaerythritol (PE) ... 

The vapor-phase synthesis of pyridines and picolines from formaldehyde, acetaldehyde, and ammonia falls in the category of four-bond formation reactions (Fig. 1). Reactions are performed in the vapor phase with proprietary catalysts. 

Chemical/Physical. Anticipated products from the reaction of methyl iodide with ozone or OH radicals in the atmosphere are formaldehyde, iodoformaldehyde, carbon monoxide, and iodine radicals (Cupitt, 1980). With OH radicals, CH2, methyl radical, HOI and water are possible reaction products (Brown et al., 1990). The estimated half-life of methyl iodide in the atmosphere, based on a measured rate constant for the vapor phase reaction with OH radicals, ranges from 535 h to 32 wk (Garraway and Donovan, 1979). 

First experiments on oxygen atom reactions with hydrocarbons, with the zone of discharge in water vapor, as well as in O2, used as a source of 0 atoms, have shown that the reaction products are formaldehyde, acetaldehyde, acids, alcohols, peroxides, i.e., products of lower degrees of conversion than that yielding H20, CO, and C02. 

Arnold s demonstration" that oxocarbenium ion intermediates can be formed through homobenzylic ether radical cation fragmentation reactions shows that mild oxidizing conditions can be used to prepare important reactive intermediates. Scheme 3.2 illustrates a critical observation in the development of an explanatory model that allows for the application of radical cation fragmentation reactions in complex molecule synthesis. In Arnold s seminal work, cleavage of the benzylic carbon-carbon bond in substrate 1 is promoted by 1,4-dicyanobenzene (DCB) with photoirradiation by a medium-pressure mercury vapor lamp. With methanol as the solvent, the resulting products were diphenylmethane (2) and formaldehyde dimethyl acetal (3). 

No information is available on the transport and partitioning of BCME in the environment. Due to the relatively short half-life in both air and water, it is unlikely that significant partitioning between media or transport occurs. Primary process for BCME degradation in air is believed to be reaction with photochemically generated hydroxyl radicals to yield chloromethyl formate CICHO, formaldehyde, and HCl. Atmospheric half-life due to reaction with hydroxyl radicals is estimated to be 1.36 h. Hydrolysis in the vapor phase is found to be slower with an estimated half-life of 25 h. 

In the USA, the regulatory focus is on consumer and worker exposure to formaldehyde vapors released from the fabric, so the test method specified is AATCC Test Method 112-2003. In this method, 1 g of fabric is suspended over 50 ml of distilled water in a sealed quart jar. The jar is placed in an oven for either 4 h at 65 °C or 20 h at 49 °C. Any formaldehyde vapors generated are absorbed by the water. An aliquot of the formaldehyde-water solution is taken and analyzed colorimetrically using the Nash reagent.Typical levels of formaldehyde found in properly processed fabrics treated with modem cross-linking reagents are less than 100 ppm. The Nash method is based on the reaction of acetylacetone with formaldehyde and an ammonium salt to form a yellow complex with an absorbance maximum at 414 nm. The mild conditions of the reaction ( pH 7, 5 min at 58 °C) eliminate many potential interferences. 

AZOTE (French) (10102-44-0) A powerful oxidizer. Reacts with water, forming nitric acid and oxygen. Violent reaction with strong reducing agents, anhydrous ammonia, alcohols, chlorinated hydrocarbons, cyclohexane, ethers, fluorine, formaldehyde, fuels, nitrobenzene, oxygen difluoride, petroleum, sodium, toluene. Incompatible with combustible materials, red phosphorus, petroleum products. Forms explosive material with propylene. Vapor reacts violently with phospham. Attacks many metals in the presence of moisture. 

Reaction of Formaldehyde Vapor with Water-Wetted Wool... 

Trezl and coworkers (12,13) studied vapor phase formaldehyde treatment of wool under vacuum. Treatments were conducted at 60 to 100 C using no catalyst or formic acid, trlmethylamine, trlethylamlne, 15-crown-5-ether and 18-crown-6-ether as catalysts. In their system, the presence of water vapor was found to Inhibit the rate of formaldehyde uptake. They found that more sites were attacked by formaldehyde vapor Chan by aqueous formaldehyde. Optimum reaction rates were observed at 70 to 80°C, and formic acid was found to be the most effective catalyst of those used. Scanning electron microscopy (SEM) did not reveal any scale damage to the wool. The treated wool was more thermally resistant, and no change In hand or dyeability of the wool was found. The treated wool had Improved tensile strength and Initial modulus with little change in elongation at break. 

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