Phenolic acid stock solutions

Figure 1. CL time profiles upon injection ("on") of two forms of the same antioxidant (T.OxlO" M) into the probe solution [50 % cumene in PhCl in the presence of AIBN as an initiator initiation rate was 1.0x10 Ms at 333 K]. Curve 1 displays the response to the injection of Y-(4-hydroxy-3,5-di-r-butyl-phenol) propionic acid taken from its organic-phase (PhCl) stock solution, while curve 2 refers to the effect of the potassium salt of this acid taken from its aqueous solution.

A stock solution is prepared by dissolving 1.0 grams of phenol in 2 liters of water to which are added 60 grams of anhydrous trisodium phosphate. The solution is adjusted to pH 6.5 with phosphoric acid, and then diluted to 5 liters to give a concentration of 200 milligrams of phenol per liter. 

Preparation of di-t-buh/lsilylene (DTBS) derivatives The diol, hydroxy acid or amino acid (100 /rg) was dissolved in acetonitrile (30 fA). N-Methylmorpholine (20 1), 1-hydroxybenzotriazole (9 yg) (dried in vacuo at 40 °C prior to preparing the stock solution 3 mg dissolved in 1 ml of acetonitrile and di-t-butylchloro-silane (3.5 fi ) were added sequentially, and the mixture was heated in a Reacti-Vial at 80 °C for 1 h (phenolic substrates and anthranilic acid) or 15 h (other substrates). The resulting solution was diluted to 100/il with ethyl acetate and used for GC and GC-MS analysis. For the derivatization of sterically... 

Setting Up As accurately as possible, calibrate several Pasteur pipets to contain 1.5 mL. In separate labeled test tubes, place 1.5 mL of a 0.2 M stock solution of each of fhe following substrates in 15 M(90%) acetic acid (a) phenol, (b) anisole, (c) diphenyl ether, (d) acetanilide, (e) 4-bromophenol, and (f) 1-naphthol. Use special care to ensure that one stock solution is not contaminated by another during any transfer operations you perform. 

A stock solution for bromination in this preparation should be supplied if not, prepare it by dissolving 1 g of potassium bromide in 6 ml of water and adding 1 g of bromine. Dissolve 0.5 g of the phenolic compound in water or 95% ethanol, and add the bromine-containing solution to it dropwise. Continue the addition until the reaction mixture begins to develop a yellow color, indicating the presence of excess bromine. Let the mixture stand for about 5 min if the yellow coloration begins to fade, add another drop or two of the solution of bromine. Add 5 mL of water to the mixture and then a few drops of 0.5 M sodium bisulfite solution to destroy the excess bromine. Shake the mixture vigorously, and remove the solid derivative by vacuum filtration. If necessary, neutralize the solution with concentrated hydrochloric acid to promote precipitation of the derivative. Purify the solid by recrystallization from 95% ethanol or aqueous ethanol. 

Substance Salicylic acid (phenolic group). Temperature 20 C Concentration O OOlM. Recrystallized material (.AR) was dried over-night tCa( l2, 20 mm. 20 j, and a stock solution in water (0 005M) was diluted fivefold in the presence of sodium hydroxide and sodium chloride, as on p. 5 2. 

---