A-Hydroxyisobutyric acid

Hydroxy-2-methylpropionic acid (a-hydroxyisobutyric acid, 2-methyllactic acid)) [594-6I-6J M 104.1, m 79 , b 114 /12mm, 212 /760mm, pK 3.78. Distd in steam, crystd from diethyl ether or benzene, sublimed at 50° and dried under vacuum. 

C4H9NO2 13027-88-8) see Dimethadione D(-)-3-bydroxyisobutyric acid (C4HSO3 1910-47-0) see Captopril a-hydroxyisobutyric acid (C4H,03 594-61-6) see Dimethadione... 

Kemp and Waters also found the oxidations of cyclohexanone and of mandelic, malonic and a-hydroxyisobutyric acids by Cr(VI) to be Mn(II)-catalysed. In these cases, as with oxalic acid, the [Cr(VI)] versus time plots are almost linear and the reaction becomes first order in substrate (or involves Michaelis-Menten kinetics), and, except at lowest catalyst concentrations, approximately first order in [Mn(II)]. Detailed examination of the initial rate of oxidation of a-hydroxyrobutyric acid as a function of oxidant concentration revealed, however, that the dependence is... 

Problem 16.1 Give a derived and lUPAC name for the following carboxylic acids. Note the common names, (a) CH,(CH,) COOH (caproic acid) (b) (CH,),CCOOH (pivalic acid) (c) (CH,)X HCH,CH,COOH ( y-methylvaleric acid) (d) C H,CH,CH,COOH (/3-phenylpropionic acid) (e) (CH,),C(OH)COOH (a-hydroxyisobutyric acid) (/) H06C(CH,),C00H (succinic acid) (no derived name). ... 

Problem 16.70 Use isopropyl alcohol as the only organic compound to synthesize (a) a-hydroxyisobutyric acid, (h) /3-hydroxy butyric acid. 

The new chemistry is based on a Sr-90/Y-90 separation using a-hydroxyisobutyric acid (a-HIB) and cation exchange chromatography (5). Once the activities are loaded onto the column, the steps to prepare the column for the a-HIB elution remove several of the possibile contaminants including rubidium and cobalt. Finally, the a-HIB elution also removes a wide range of other elements as well, leaving strontium on the ion exchange column (6). 

Hydroxy-5-iodobenzoic acid see 5-iodosaIicylic acid. a-Hydroxyisobutyric acid see 2-hydroxy-2-methylpropionic acid. 

Diethyl ester of (+)-taTtaric acid 0.105 a-Hydroxyisobutyric acid No effect... 

Acesulfame-K, dulcin, saccharin Cl8 column Acetonitrile 50 mM a-hydroxyisobutyric acid, pH 4.5 (2.2 3.4, v/v) with 2.5 mM hexadecyltrimethyl-ammonium bromide UV—233 nm 65... 

The first report demonstrating the feasibility of indirect detection in CE was published in 1987 by Hjerten et al.45 who employed indirect UV absorbance detection for the analysis of both inorganic ions and organic acids. The UV-background-providing electrolyte was 25 mM sodium veronal, pH 8.6, and detection was monitored on-column at 225 nm. In 1990, the first separation of alkali, alkaline earth, and lanthanide metals was reported by Foret et al46 Indirect UV detection at 220 nm was employed to detect 14 metals in 5 min, with baseline resolution achieved between all but two of the components. The baseline showed a reproducible upward drift between 1 and 3 min. The UV-absorbing component of the electrolyte was creatinine, with a-hydroxyisobutyric acid introduced to complex with the lanthanides and improve resolution. 

Capillary electrophoresis Capillary electrophoresis (CE) is used to analyze sodium, potassium, calcium, and magnesium in water samples. The detection is conducted by reverse absorbance measurements. Sufficient separation of the four cations is established with an electrolyte solution of 5 mM imidazole/6.5 mM a-hydroxyisobutyric acid/2 mM 18-crown-6 ether of pEI 4.1 [42]. CE with a contactless conductometric detector is used to determine small anions and cations in water samples from different sources. 2-(N-Morpholino)ethanesulfonic acid/histidine-based (Mes/Elis) electrolytes are used for direct conductivity detection of anions and cations, while ammonium acetate is used for indirect conductivity determination of alkylammonium salts. Eor the simultaneous separation procedure, involving dual-opposite end injection, an electrolyte consisting of 20 mM Mes/EIis, 1.5 mM 18-crown-6 and 20 mM cetyltri-methylammonium bromide provides baseline separation of 13 anions and cations in less than 6 min [43]. Also CE with a capacitively coupled... 

Rare earths Dowex-50 5% ammonium citrate, pH 3-3.5, or 0.2-0.4 M a-hydroxyisobutyric acid, pH 4.0-4.6, or 0.025 M ethylene-diaminetetraacetic acid (EDTA)... 

C7H1202 5-methyl-4-hexenoic acid 5636-65-7 490.15 42.939 1,2 11558 C7H1204 a-hydroxyisobutyric acid acetate methyl ester 57865-37-9 464.16 40.452 2... 

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