Formaldehyde Water

The intermolecular frequencies are reported in Table 3.56 at various levels of theory, along with the calculated SCF intensities in the last column. With only one exception, the correlated frequencies are somewhat higher than the SCF values. Because of the bent nature of the H-bond in HjCO -HOH, the H-bond stretching frequency is not particularly pure. 

Its frequency of about 180 cm is quite similar to that of the water dimer. The intensity is only 30 km/mol, considerably weaker than the same band in (H20)2. The two in-plane bends listed in Table 3.56 are of quite different frequency. The first, of higher frequency, corresponds to a distortion in which the XO-H angle becomes straighter and the O-HO angle more acute, while the lower refers to an overall straightening of both aspects of the H-bond. The other intermolecular bends are all of a symmetry. The out-of-plane distortion is the highest frequency mode of all and the torsion the lowest. The latter frequency is quite a bit smaller than that of the torsional mode of water dimer. Agreement with available experimental observation in solid Ar matrix is moderate. 

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In methanol—formaldehyde—water solutions, increasing the concentration of either methanol or formaldehyde reduces the volatility of the other. Vapor-hquid-equihbrium data (8,27) for several methanolic formaldehyde solutions ate given in Table 2. The flash point varies with composition, decreasing from 83 to 60°C as the formaldehyde and methanol concentrations increase (17,18). 

Aqueous Formaldehyde. Water solutions of formaldehyde consist mainly of telomers of methylene glycol having <100 ppm of the formaldehyde as CH2O (5). Alcohols form hemiformals with aqueous formaldehyde according to the following, where n = 1,2,3, etc. 

Thermal Stability. Dimethyl sulfoxide decomposes slowly at 189°C to a mixture of products that includes methanethiol, formaldehyde, water, bis(methylthio)methane, dimethyl disulfide, dimethyl sulfone, and dimethyl sulfide. The decomposition is accelerated by acids, glycols, or amides (30). This product mixture suggests a sequence in which DMSO initially undergoes a Pummerer reaction to give (methylthio)methano1, which is labile and reacts according to equations 1—3. Disproportionation (eq. 4) also occurs to a small extent ... 

Ethylene Oxide Purification. The main impurities ia ethylene oxide are water, carbon dioxide, and both acetaldehyde and formaldehyde. Water and carbon dioxide are removed by distillation ia columns containing only rectifying or stripping sections. Aldehydes are separated from ethylene... 

Another elegant example of the thermal generation and subsequent intramolecular cycloaddition of an o-QM can be found in Snider s biomimetic synthesis of the tetracyclic core of bisabosquals.2 Treatment of the starting material with acid causes the MOM ethers to cleave from the phenol core (Fig. 4.3). Under thermal conditions, a proton transfer ensues from one of the phenols to its neighboring benzylic alcohol residue. Upon expulsion of water, an o-QM forms. The E or Z geometry of the o-QM intermediate and its propensity toward interception by formaldehyde, water, or itself, again prove inconsequential as the outcome is decided by the relative thermodynamic stabilities among accessible products. 

Methanol conversion, in formaldehyde manufacture, 12 115 Methanol converters, 16 308 Methanol-formaldehyde-water solutions, 12 109... 

A catalytic decomposition of triphenylphosphine has been reported [38] in a reaction involving rhodium carbonyls, formaldehyde, water, and carbon monoxide. The following reactions may be involved (Figure 2.39) ... 

Fuel cells using directly liquid fuels are advantageous in this aspect. Methanol, formaldehyde (water solution), formic acid (water solution) and hydrazine are among fuels relatively easy to oxidize electrochemically. Alcohol and hydrocarbon with larger molecular weight are much harder to oxidize completely to C02- Other qualifications to be considered are price, availability, safety, energy density and ease of handling. 

Adhesive. Urea-formaldehyde water-based dispersions are the most widely used particleboard binders. The low-cost, rapid curing, and colorless properties of urea-formaldehyde adhesives make them the adhesive of choice for most interior particleboard. These adhesives have been continuously improved by the resin manufacturers, resulting in reduced press times without detrimental effects on their storage life or handling characteristics. 

The photooxidation of alkyl iodides represents one of the early methods by which the oxidation of alkyl radicals was studied. Thus Bates and Spence,11 in 1931, found that the chief products in the photooxidation of methyl iodide were methanol, formaldehyde, water, and iodine. For these products they postulated the following reactions... 

Hydrogen bonding must have an effect on the electron density distribution of a molecule. In principle, this should be observed in the deformation density distributions discussed in Chapter 3. There are, in fact, two methods available. One is purely theoretical, in which the calculated deformation density for a hydrogen-bond dimer or trimer is compared with that of the isolated molecule. The other method compares the experimental deformation density of a hydrogen-bonded molecule in a crystal structure with the theoretical deformation density of the isolated molecule. Formamide has been studied by both methods [298, 380], and there appear to be significant differences in the results which are not well accounted for. Theoretical difference (dimer vs. monomer) deformation density maps have been calculated for the water dimer and the formaldehyde-water complex [312]. When those for the water dimer are decomposed into the components described in Chapter 4, a small increase in the charges on the atoms in the O-H -O bond due to the charge-transfer component is predicted [312]. 

Dimitrova, Y. and Peyerimhoff, S. D., Theoretical. study of hydrogen-bonded formaldehyde-water complexes, J. Phys. Chem. 97, 12731-12736 (1993). 

Formaldehyde-water solution. Mix 50 ml of 38% formaldehyde with 50 ml of distd w in a 400-ml beaker, add 4 drops of 1% phenolphthalein or thymolphthalein indicator (0.8g per 100ml ethanol) and neutralize with carbonate-free 0.5N NaOH soln dropwise to a pink color (pH 8.6) on glass-calomel electrode system Standard sodium hydroxide, 0.5N. Dissolve 20g of carbonate-free NaOH in 500ml CO2-free water, add enough Ba chloride to more than 2 liters distd w to precipitate carbonate present, let the Ba carbonate settle, and filter into a 1 liter volumetric flask. Standardize the NaOH soln by adding it. from a buret into a soln of 2 g of potassium acid phthalate (weighed accurat ely on an analytical balance), and four drops of phenolphthalein indicator in 75—100ml COa-free water contained in a 150-ml beaker until the first appearance of a pink end point... 

Procedure [or Ammonium Nitrate. Transfer a 25 ml aliquot from the bottle of step 6 to 100 ml of the neutralized formaldehyde-water soln in a 400-ml beaker, add 4 drops of 1% phenolphthalein (or thymolphthalein) indicator and titrate to a pink color with, 0.5N NaOH. Add 2 ml of NaOH in excess, cover the beaker, and let stand for 5 mins. Back-titrate with O.IN HCl to pH 8.5 (glass-calomel electrode system)... 

Several examples of the Sc(OTf)3-catalyzed aldol reactions in micellar systems are shown in Table 14-7. Not only aromatic but also aliphatic and a,/(-unsaturated aldehydes reacted with silyl enol ethers to afford the corresponding aldol adducts in high yields. Formaldehyde/water solution also worked well. Ketene silyl acetal 4, which is known to be hydrolyzed very easily even in the presence of a small amount of water, reacted with an aldehyde in the present micellar system to afford the corresponding aldol adduct in a high yield. 

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. 

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