Formaldehyde percentage composition

The next example will provide practice with the concept of mass percentage. In this example we will start with a compound (formaldehyde, CH2O) whose formula is given and obtain the percentage composition. 

Cyclotriveratrylenes are made by the condensation of veratrole with formaldehyde and were a curiosity when they were first prepared by Robinson in 1915 [47], At the time she believed the compound to be a dimer, 2,3,6,7-tetramethoxy-9,10-dihydroxyanthracene. The reason for this was that the composition of the original compound was determined by elemental analysis. This technique determines the percentage of hydrogen and carbon in the sample which would be identical for a dimer, trimer or any other cyclic product with the same proportion of carbon to... 

Alkylphenols are weak acids, but substitution on the alkylphenol with methylene or sulphur increases the acidity. The methylene-substituted phenates originate from a condensation product between the alkylphenol and formaldehyde. Phen-ate sulphides can be obtained by at least three sulphurization reagents (1) sulphur monochloride, (2) sulphur dichloride and (3) elemental sulphur. The percentage of sulphur contained in a phenate sulphide detergent directly dictates the chemistry of the detergent because of the variable ratio of sulphur atoms to alkylphenol substrate and the variety of ways the sulphur atoms can be attached to the alkylphenol. Phenol detergents are more difficult materials to describe based on analytical data. Nevertheless, the same chemical concepts applied to sulphonates also apply to phenates. Table 7.2 summarizes the compositional ranges typically observed in phenate lubricant additives. 

One will note the high mole percentage of oxidizer needed to balance this reaction which corresponds to a high weight percentage of inter-pore oxidizer salt deposited in the overall composite. The resorcinol-formaldehyde/ammonium nitrate (RFIAN) reaction shown... 

The efficacy at HTA is based on its formaldehyde content which, however, is only released in acid media. According to its composition HTA is the formaldehyde releasing compound with the highest percentage of bound formaldehyde. As with formaldehyde, HTA preferably attacks bacteria and not mould producing fungi to such an extent. 

Benzyl alcohol is listed in the EC positive list of preservatives for cosmetic products (maximum concentration for application 10.000 mg/litre) as a preservative it may be useful also in pharmaceutical preparations. Percentage of use in US cosmetic formulations 0.32%. The activity of benzyl alcohol is not very much affected by the pH and the composition of the medium to be protected. As an auxiliary solvent with antimicrobial efficacy benzyl alcohol is used in preservative compositions for industrial fluids (Paulus et al., 1970a). A well-known preservative for cosmetics and industrial fluids is benzyl alcohol mono(poly)hemiformal (Paulus, 1976) which is a formaldehyde releasing compound and therefore listed under 3.1.2. 

---