Formaldehyde forms

I ovolac Synthesis and Properties. Novolac resins used in DNQ-based photoresists are the most complex, the best-studied, the most highly engineered, and the most widely used polymers in microlithography. Novolacs are condensation products of phenoHc monomers (typically cresols or other alkylated phenols) and formaldehyde, formed under acid catalysis. Figure 13 shows the polymerization chemistry and polymer stmcture formed in the step growth polymerization (31) of novolac resins. 

Methanol substitution strategies do not appear to cause an increase in exposure to ambient formaldehyde even though the direct emissions of formaldehyde have been somewhat higher than those of comparable gasoline cars. Most ambient formaldehyde is in fact secondary formaldehyde formed by photochemical reactions of hydrocarbons emitted from gasoline vehicles and other sources. The effects of slightly higher direct formaldehyde emissions from methanol cars are offset by reduced hydrocarbon emissions (68). 

Uses. The largest usage of PCl is to produce phosphonic acid, H PO, which in reaction with iminodiacetic acid and formaldehyde forms a glyphosate intermediate that is decarboxymethylated to glyphosate, an effective nonselective herbicide (see Herbicides). Phosphoms trichloride is also a convenient chlorinating reagent for producing various acyl and alkyl chlorides. 

Ortho- and/ i ra-phenylphenols are commercially significant biphenyl derivatives that do not involve biphenyl as a starting material. Both are produced as by-products from the hydrolysis of chlorobenzene [108-90-7] with aqueous sodium hydroxide (68). o-Phenylphenol, ie, l,l-biphenyl-2-ol [90-43-7], particularly as its sodium salt, is widely used as a germicide or fungicide. Pi ra-phenylphenol [92-69-3] with formaldehyde forms a resin used in surface coatings. 

Physical and Chemical Properties. The reaction of urea and formaldehyde forms a white soHd. The solubihty varies with the methylene urea polymer chain length longer-chain, higher molecular-weight UF polymers are less water-soluble than short-chain polymers. Physical properties of the methylene urea polymers which have been isolated are compared to urea in Table 1. 

Cyanuric acid readily dissolves in aqueous formaldehyde forming tris(hydroxymethyl)isocyanurate [10471-40-6] (THMIC) which can be isolated by evaporation (11). THMIC in turn reacts with acetic anhydride to yield tris(acetoxymethyl)isocyanurate [54635-07-3], either thionyl chloride or phosphoms pentachloride to give tris(chloromethyl)isocyanurate [63579-00-0], and phenyl isocyanate in pyridine to yield tris(A/-phenylcarbamoxymethyl) isocyanurate [21253-39-4] in 87% yield (65). Reaction of CA with paraformaldehyde and 2,6-dicyclohexylphenol yields... 

The reaction of benzoxazine in die presence of 2,6-xylenol does not occur until 135 C, presumably because die hydrogen-bonded intermediate depicted for the 2,4-xylenol reaction (Fig. 7.19) cannot occur. All three types of linkages are obtained in diis case. Para-para methylene-linked 2,6-xylenol dimers, obtained from the reaction of 2,6-xylenol with formaldehyde, formed in the decomposition of the benzoxazine (or with other by-products of that process) dominate. Possible side products from benzoxazine decomposition include formaldehyde and CH2=NH, either of which may provide the source of methylene linkages. Hie amount of ortho-para linkages formed by reaction of 2,6-xylenol with benzoxazine is low. Ortho-ortho methylene-linked products presumably form by a decomposition pathway from benzoxazine (as in Fig. 7.18). 

The second channel, producing CO, was first observed by Seakins and Leone [64], who estimated 40% branching to this channel. Later measurements by Lockenberg et al. [65] and Preses et al. [66] concluded the branching to CO is 18%. Note that decomposition of formaldehyde formed in reaction (26a) is not a possible source of CO due to the large barrier for formaldehyde decomposition. Marcy et al. [67] recently combined time-resolved Lourier spectroscopy experiments with direct dynamics classical trajectory calculations to examine the mechanism of the CO product channel. They observed two pathways for CO formation, neither of which involve crossing a TS. 

The addition of copper to a boiling solution of benzenesulphonyl azide in methanol gave benzenesulphonamide 18 (80%) as the major product together with minor amounts of methylenebis(benzenesulphon-amide) 22 and 1,3,5-tris (benzenesulphonyl) hexahydro-s-triazine 23, resulting from condensation of 18 with the formaldehyde formed in the reaction 33>. Cuprous chloride was even more effective, but cuprous... 

The early addition of Dimedon is reported234 to depress the formation of hexamethylenetetramine from formaldehyde in the presence of ammonia. O Dea282 found that the activated methylene center, sometimes formed in periodate oxidations of carbohydrates, reacts appreciably with the formaldehyde formed, thus giving low yields of apparent formaldehyde. He was able to depress this side reaction by the use of lowered temperatures and by the addition of benzaldehyde or of p-hydroxybenzaldehyde. The analyses for formaldehyde have often been more successful at a pH of 7.5 than at lower pH values.57, 68 59a 60 264... 

The conclusions on the rate limiting step are again supported by the differences in product selectivity if completely deuterated methanol is used the selectivity to dimethylether relative to formaldehyde is much larger. This is shown for the three catalysts in Figures 10-12, in which the ratio of the amounts of dimethylether and formaldehyde formed is plotted as a function of temperature. In the case of CH,0D, the water observed is a mixture of H20, HDO, and D20, most of it being HDO. 

Calibration. Most aldehydes, except formaldehyde, form two geometrical isomers of the derivatives and appear as two peaks in the chromatogram. The sum of these two peak areas was used in the calibration measurements. A six-point calibration curve for nine carbonyl compounds was measured. The calibration range was 0.1-50 ppb, except for (E)-2-nonenal, where the calibration range was 0.01-5 ppb. The matrix used for calibration solutions was 5% ethanol solution, pH 4.5. Correlation coefficient (Rh values indicate that this method can be used for analysis of aldehydes in a wide range of concentrations (Table 1). 

Essential Information Most aldehydes, except formaldehyde, form two geometrical isomers of the derivatives that are represented by two peaks in the chromatogram. 

In this reaction system traces of ethane formed by the termination and probably traces of formaldehyde (formed by a hydrogen abstraction by formyl) are also formed, but their concentrations are always much less than those of CH4 and CO. 

The amino groups of the bases react reversibly with aldehydes but to a lesser extent than do the more strongly basic amino groups of the amino acids. Formaldehyde forms adducts containing either one or two molecules of the aldehyde (Eq. 5-15). 

The slower conversion of the anomerized D-glucofuranosides into D-gluco-pyranosides was studied with a higher concentration, of acid. The concentration of furanosides was followed by determining the amount of formaldehyde formed by periodate oxidation. It was concluded that the same acyclic ion (16) is formed from both furanoid anomers, and that ring closure gives a mixture of pyranosides similar to that found in the equilibrium mixture of pyranosides. 

Methanesulfonic acid. 4 The substrate is the 0-D-furanoside the data are for 10 (k + kt), determined polarimetrically the anomerized mixture contains 63% of the ti and 37% of the a form. The substrate is the anomerized mixture the data are for 10 kt, the overall rate constant, determined from the formaldehyde formed on oxidation with periodate. 

In order to differentiate between the two formaldehyde forming reactions in the case of propylene, reaction (6), attack on CH3 group, and (8), attack on CH2 group of the double bond, Avramenko and Kolesnikova carried out experiments with 1,3-butadiene, which leaves only the latter alternative. Quantitative analyses were carried out only for the carbonyl compounds and the acids. Carbonyl compounds consisted of acrolein, formaldehyde, and higher aldehydes. Acrolein appeared to be a primary product, and formaldehyde and acid secondary ( quadratic ) products. The postulated primary reaction was... 

When the reaction products of the reaction involve the nitrogen atoms of nucleophiles in the formation of heterocyclic derivatives, the formation of 1,1-diamino derivatives is usually used to prepare polyazacyclic derivatives221. Scheme 48 shows222 the formation of fused polyazapolycyclic compounds through a condensation between 1,3-diaminopropane and glyoxal to prepare the 1,1-diamino derivative 161. The subsequent reaction of 161 with formaldehyde forms fused addition products (162). 

Air drawn through a solid sorbent tube containing 10% (2-hydroxymethyl) piperidine on XAD-2 (120 mg/60 mg) oxazolidine derivative of formaldehyde formed desorbed into toluene under ultrasonic conditions (60 min) analyzed by GC-FID (NIOSH Method 2541,1989) recommended air flow 200 mL/min sample volume 15 L. 

Alternatively, a measured volume of air drawn through an impinger containing ammonium acetate and 2,4-pentanedione formaldehyde forms a fluorescence derivative, 3,5-diacetyl-l,4-dihydrolutidine fluorescence of the solution measured by a filter fluorometer (Dong and Dasgupta, 1987). 

With urea, formaldehyde forms two stable IV.O-hemiacetals (Figure 9.25) a 1 1 adduct ( methylol urea ) and a 1 2 adduct ( dimethylol urea ). When they are heated, both compounds are converted to macromolecular IV.lV-acetals (Figure 9.26). A three-dimensionally cross linked urea/formaldehyde resin is produced it is an important plastic. 

The a-aminocarbonyls are not only precursors of pyrazines, but can also lead to pyrroles,242 as well as imidazoles and oxazoles.243 Pyrolysis-GC-MS is relatively readily available and provides a productive technique. As mentioned previously, Wnorowski and Yaylayan212 had shown that, although more products are formed on pyrolysis than in aqueous media, most of the products identified in aqueous systems are present in pyrolysates with identical label distribution, even though the proportions may differ. Pyrolysates (250 °C, 20 s) of model systems of carbonyl and [2-13C]Gly or Ala were analysed. In the butanedione-Gly system, acetaldehyde and formaldehyde formed by decomposition of the carbonyl are unlabelled, but formaldehyde by Strecker degradation is labelled. 2,4,5-Trimethyloxazole was found to be unlabelled, being formed from acetaldehyde, but 4,5-dimethyloxazole was 15% mono-labelled, i.e., 15% of the precursor formaldehyde had been derived by Strecker degradation. 

Trinitromethane reacts with formaldehyde forming trinitroethyl alcohol (Hurd and Starke [51]) ... 

The photooxidation of formaldehyde was first studied by Carruthers and Norrish87 who found that 45% of the initial formaldehyde forms formic acid, 20% forms water, and carbon monoxide, 3% forms carbon dioxide and hydrogen, while 32% is polymerized. The chain length was of the order of 10. 

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