Isocaproate

In the body, natural steroid hormones are synthesized from cholesterol. The rate-determining step is the oxidation of the cholesterol side chain, which forms pregnenolone and isocaproic aldehyde. 

Fig. 8.3. GC chromatogram of mixed silage juice standards using a Carbopack B-DA column. Identity and concentrations (before diluting 4 1 standard 0.3 M oxalic acid) a, ethanol, 1 mg mM b, acetic acid, 1.25 mg mM c, propionic acid, 0.25 mg ml" d, isobutyric acid, 0.25 mg mM e, n-butyric acid, 0.25 mg mM f, pivalic acid (internal standard), 0.4 mg mM g, isovaleric acid, 0.25 mg mM h, lactic acid, 10 mg mM i, n-valeric acid, 0.25 mg mM j, isocaproic acid, 0.25 mg mM k, n-caproic acid, 0.25 mg mM.

A 7-day-old girl has had a seizure. The mother explains that the baby has been vomiting and having difficulty feeding for the past 2 days. There is also a strange, sweet smell to her diapers. Physical examination is unremarkable, except for indications of dehydration. Serum test results show normal levels of glucose and ammonia. Urinalysis reveals the presence of a-keto-isocaproate and a-keto-isovalerate. 

METHYL y-METHYL-y-NITROVALERATE (Isocaproic acid, Y-nitro, methyl ester)... 

Later investigators alcoholyzed imidate salts of other monobasic acids to obtain ortho esters of acetic [13, 14], propionic [15], butyric, valeric, caproic, isocaproic, benzoic [16], and phenylacetic acids [17]. For the latter alcoholysis reactions, the reaction time varies from a few days for the production of methyl orthopropionate to six weeks for ethyl orthobenzoate. McElvain reported that the reaction time is drastically cut by carrying out the reaction in boiling ether [18] or petroleum ether [19]. These conditions provide a reaction temperature below the decomposition point of the imidate salt to the amide. 

N.A. Bromelain, citric acid, vanillin, methyl-n-propyl ketone, valerianic acid, malic acid, isocaproic acid, acrylic acid.100 Unripe fruits improve digestion, increase appetite, relieve dyspepsia. Ripe fruits reduce excessive gastric acid. 

A) a-Bromoisocaproic Acid.—Five hundred grams (4.3 moles) of commercial isocaproic acid is mixed with 250 cc. of benzene in a 2-1. round-bottomed flask, and the water and benzene are removed by distillation through a short column until the temperature of the vapors reaches ioo°. The temperature rises rapidly as soon as the last of the benzene is removed. The residual acid is cooled to room temperature, 743 g. (4.65 moles, 243 cc.) of dry bromine (Note 1) is added, and the flask is fitted with a long condenser and placed in an oil bath. The top of the condenser is connected to an empty 500-cc. Erlenmeyer flask which acts as a safety flask, and this in turn leads to a gas-absorption trap (Note 2). Ten cubic centimeters of phosphorus trichloride is added to the mixture through the top of the condenser, and the flask is heated to 80-85°. The bromination proceeds smoothly at this temperature and is allowed to continue for eight to fifteen hours until the dark red color of bromine disappears from the condenser. When it has, the temperature is raised to 100-105° and kept there two hours. The contents of the flask are transferred to a i-l. modified Claisen flask or a flask attached to a Widmer column and distilled. The fraction... 

This is a general method for preparing a-bromo acids. By using exactly analogous directions -bromo- -caproic acid may be obtained in 65-70 per cent yields from w-butylmalonic ester a-bromo-isocaproic acid in 65-70 per cent yields from isobutylmalonic ester and a-bromo-/3-methyl valeric acid in 75-80 per cent yields from sec.-butylmalonic ester. 

GC unit. Peak identification is as follows 1, benzylalcohol 2, testosterone propionate 3, testosterone isocaproate 4, testosterone phenylpropionate 5, testosterone decanoate 6, oil matrix (b) GC analysis of the transfer (4 pd) from the micro SEC system (c) Direct GC analysis of a standard solution of the steroid esters. Reprinted from Proceedings of the 10th Symposium on Capillary Chromatography, M. Ghys et al, On-line micro size-exclusion chromatography-capillary gas chromatography, 1989, with permission from Wiley-VCH. 

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