Acetyl number acid value

Stuer et al. [46] evaluated the presence of the 25 most used pharmaceuticals in the primary health sector in Denmark (e.g., paracetamol, acetyl salicylic acid, diazepam, and ibuprofen). They compared PECs with experimental determinations and they conclude that measured concentrations were in general within a factor of 2-5 of PECs. Carballa et al. [45] also determined PECs for pharmaceuticals (17), musk fragrances (2) and hormones (2) in sewage sludge matrix. For that purpose they used three different approaches (1) extrapolation of the per capita use in Europe to the number of Spanish inhabitants for musk fragrances (2) annual prescription items multiplied by the average daily dose for pharmaceuticals and (3) excretion rates of different groups of population for hormones. They indicated that these PECs fitted with the measured values for half of them (carbamazepine, diazepam, ibuprofen, naproxen, diclofenac, sulfamethoxazole, roxithromycin, erythromycin, and 17a-ethiny I e strad iol). 

The acetyl value is the number of mg of KOH required to neutralize the acetic acid produced by the hydrolysis of 1 g of acetylated fat and is a measure of free hydroxyl groups present in the oil. The acetyl number of peanut oil (8.5-9.5) is lower than other vegetable oils but higher than coconut oil, palm oil, and the animal fats and oils. 

Acetyl number (value) n. Number of milligrams of potassium hydroxide required to neutralize the acetic acid set free from 1 g of an acetylated compound when the latter is subjected to hydrolysis. 

In the studies conducted by Reetz, rhodium catalysts based on mixtures of monodentate phosphites, monodentate phosphonites and combinations of the two were screened in the enantioselective hydrogenation of a- and /9-N-acetyl-de-hydroamino acid esters, enamides and dimethyl itaconate [40], and a number of the more striking positive results are listed in Table 36.3. An enhanced ee-value was found mostly with combinations of two phosphonites, or one phosphonite and one phosphite, in particular when one of the ligands carries a bulky substituent and the other a small one. 

Acetyl values were determined by base hydrolysis of the acetyl groups of a weighed sample, followed by back-titration to determine the number of milliequivalents of acetic acid. 

The initial rate of 2-MN acetylation depends on the framework Si/Al ratio of the zeolite catalyst.[27] For a series of dealuminated BEA samples (by treatment with hydrochloric acid or with ammonium hexafluorosilicate), the acetylation rate passes through a maximum for a number of framework A1 atoms per unit cell (/VA() between 1.5 and 2.0 (Si/Al ratio between 30 and 40). The activity of the protonic sites (i.e. the TOF) increases significantly with Si/Al from 420 h 1 for Si/Al = 15 to 2650 h 1 for Si/Al = 90. It should be noted that similar TOF values could be expected from the next nearest neighbour (NNN) model. Indeed all the framework A1 atoms of the zeolite (hence all the corresponding protonic acid sites) are isolated for Si/Al ratio 10.5. Therefore the acid strength of the protonic sites is then maximal as well as their activity.[57,58] This was furthermore found for m-xylcnc isomerization over the same series of BEA zeolites.1271 This increase in TOF for... 

Cellulose acetate is an ester of cellulose and acetic acid. Hence, hydrolysis takes place when the pH of the solution with which a cellulose acetate membrane is in contact is too high or too low, lowering the degree of acetylation, defined as the number of hydroxyl groups (total of three in one D-glucopyranose unit) that can be acetylated. Because a degree of acetylation above 2.5 is required for satisfactory salt rejection in seawater desalination, excessive hydrolysis results in poor membrane performance. The pH values between 5 and 7 should be maintained when cellulose acetate membranes are used. ... 

Numerous other protein-surfactant systems when subjected to Scatchard analysis give curves that extrapolate to a number of specific binding sites very close to the number of cationic amino acid residues in the protein. Furthermore, chemical modification of the cationic sites, e.g., in the case of lysyl residues by acetylation, shifts the Scatchard plots to give lower values of n [32], Despite these interesting observations, Scatchard analysis should be treated with a degree of caution it is not entirely clear why such a good correspondence between n and the number of cationic sites is obtained, since the binding sites must only approximate to independence and are certainly not chemically identical. 

The deacetylation process involves the removal of acetyl groups from chltln molecules. The DAC is defined as the average number of glucosamine units per 100 monomers expressed as a percentage. It determines the content of free amino groups [-NH2] in the chitosan and is one of the most important chemical characteristics that influence the physicochemical properties, biological properties, antibacterial activity, and applications of chitosan. In other words, DAC value determines the functionality, reactivity, polarity, and water solubility of the polymer. Chitin does not dissolve in dilute acetic acid. When chitin is deacetylated to a certain degree ( 60% deacetylation] where it becomes soluble in the acid, it is referred to as chitosan [18, 21]. 

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