Esters Type

The threat of accidental misuse of quaternary ammonium compounds coupled with potential harmful effects to sensitive species of fish and invertebrates has prompted some concern. Industry has responded with an effort to replace the questionable compounds with those of a more environmentally friendly nature. Newer classes of quaternaries, eg, esters (206) and betaine esters (207), have been developed. These materials are more readily biodegraded. The mechanisms of antimicrobial activity and hydrolysis of these compounds have been studied (207). AppHcations as surface disinfectants, antimicrobials, and in vitro microbiocidals have also been reported. Examples of ester-type quaternaries are shown in Figure 1. 

Plasticizers (qv) can range in composition from the ester types, ie, epoxies, phosphate, amides, etc. The effect of any one of these on curing is usually pH-dependent. However, it is pmdent to investigate each on a case by case basis. 

Ester type of mono- unless otherwise noted. 

Trade name Ester type Acid Composition PEG POE" Functions Manufacturer... 

Observable Characteristics - Physical State (as normally shipped) Liquid Color Colorless Odor Characteristic acrylic odor sharp, fragrant acrid slightly nauseating sharp, ester type. 

The transformation of an ester carbonyl group to a difluoromethylene group, which IS usually difficult to perform, can be accomplished by conversion to the thiaesier followed by treatment with diethylaminosulfur trifluoride (DAST). A vanety of ester types react efficiently, although the reaction fails with lactones. Remarkably, trimethylsilylmethyl esters carry through the proeedure with the silyl group intact [13] (equation 17). 

Following is an ester type macroazoinimer [51] starting from the poly(ethylene glycol), 4,4 -azobiscy-ano pentanoyl chloride, and methacryloyl chloride. 

Figure 3 DSC thermograms for (a) homopolymer of an ester type macroazoinimer, MAIM-1000, having PEG-1000 units and (b) styrene-PEG-1000 crosslinked polymer with MAIM-1000. Source Ref. 50.

Maes RA. 1975. Organic thiophosphate esters (type A B procedures). In Sunshine 1, ed. Methodology for analytical toxicology. Vol. 1, Cleveland, OH CRC Press, Inc., 288-291. 

Processing aids (Oils, ester type plasticizers, etc.)... 

Pyraflufen-ethyl (ester type) and E-3 are quantitatively converted to E-2 by the sulfuric acid treatment, but not E-1 (free acid type) therefore, methylation of E-1 to E-15 (ester type) is a necessary step for accurate analysis of total residues. 

Triisopropylbenzenesulfonyl)-3-nitro-1,2,4-triazole in the presence of 4-rtiorpholine pyridine-1-oxide was used with advantage as a coupling reagent for a solid-phase (p-alkoxybenzyl ester type resin) synthesis of peptides such as Leu-AIa-Gly-Val-OH or Leu-enkephalinamide (Tyr-Gly-Gly-Phe-Leu-NHs). The overall yield in the latter case was 70%, the purity of the peptide was 85-90%, and racemization was virtually zero.[38]... 

Griffin, T.J. Jr. "Phosphate Ester-Type Reaction Product and Method of Preparing Same," US Patent 4,153,649(1979). 

M., Sugiura, M., Species difference and characterization of intestinal esterase on the hydrolyzing activity of ester-type drugs, Jpn. J. Pharmacol. 

Van Zoonen et al. [19,20] employed an alternative approach, in an attempt to overcome the limited aqueous solubility of diaryloxalate ester-type POCL reagents. In this work, granular TCPO was mixed with controlled pore glass and packed in a flow cell, forming a solid-state TCPO reactor. When this was used in conjunction with a flow system, some of the TCPO dissolved in the carrier solution. Numerous difficulties were encountered with this approach, namely, limited reactor lifetime (approximately 8 h) and low CL emission obtained as the carrier became more aqueous (a 90% reduction of CL intensity occurred when the aqueous content of the carrier stream comprised 50% water, as compared to pure acetonitrile). The samples also required dilution with acetonitrile to increase the solubility of TCPO in the sample plug. 

The answer is c. (Hardman, p 340. Katzung, p 437.) Of the listed agents, only bupivacaine is an amide. Allergy to amide-type local anesthetics is much less frequent than with ester-type local anesthetics, such as benzo-caine patients who demonstrate an allergy to one such drug will be allergic to all of them... 

The answer is a. (Hardman, p 338. Katzung, pp 438-439.) Ester-type local anesthetics are mainly hydrolyzed by pseudocholinesterases. Amide-type local anesthetics are hydrolyzed by microsomal enzymes in the liver. Of the listed agents, only lidocaine is an amide and can be influenced by liver dysfunction. 

The answer is d. (Hardman, p T36J The addition of a vasoconstrictor, such as epinephrine or phenylephrine, to certain short-acting, local anesthetics is a common practice in order to prevent the rapid systemic absorption of the local anesthetics, to prolong the local action, and to decrease the potential systemic reactions. Some local anesthetics cause vasodilation, which allows more compound to escape the tissue and enter the blood. Procaine is an ester-type local anesthetic with a short duration of action due to rather rapid biotransformation in the plasma by cholinesterases. The duration of action of the drug during infiltration anesthesia is greatly increased by the addition of epinephrine, which reduces the vasodilation caused by procaine. 

CD was observed in the corresponding ester-type amphiphiles which did not produce helices. 

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