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Properties of substance:

benzeneboronic acid

Synonyms:

phenylboronic acid

Group of substances:

elmentoorganic

Empirical formula (Hill's system for organic substances):

C6H7BO2

Structural formula as text:

C6H5B(OH)2

Molar/atomic mass: 121.94

Decomposition temperature (°C):

110

Solubility (g/100 g of solvent):

benzene: 1.75 (25°C) [Ref.]
diethyl ether: 30.2 (25°C) [Ref.]
ethanol: soluble [Ref.]
methanol: 178 (25°C) [Ref.]
water: 2.5 (25°C) [Ref.]
xylene: 1.2 (25°C) [Ref.]

Synthesis 1:

Reference: A Textbook of inorganic chemistry. Organometallic compounds. - vol.XI, part 1. - London, 1928 pp. 229

The magnesium compound from 50 grams of bromobenzene in 200 c.c. of ether is saturated with the boron trifluoride from 52 grams of potassium borofluoride, 8 grams of boron trioxide, and 100 c.c. of concentrated sulphuric acid. After boiling for two hours under reflux, the product is ice cooled, and decomposed by cautiously adding 60 c.c. of water. The ether layer is then separated off, and the residue extracted several times with ether, the solvent removed, and the solid obtained boiled with 100 c.c. of water for one hour on the water-bath and filtered whilst hot. On slowly cooling, pure phenyl boric acid separates in snow-white bushy needles, several centimeters in length, M.pt. 216°C.

Dissociation:

pKa (1) = 8.9 (°C, water)

Standard molar enthalpy (heat) of formation ΔfH0 (298.15 K, kJ/mol):

-719.6 (s)

LD50 (mg/kg):

740 (rats, oral)
320 (mice, intravenous)
500 (mice, intraperitoneal)

References:

  1. Armarego W. L. F. Purification of Laboratory Chemicals. - 7ed. - 2013. - pp. 521
  2. Dictionary of organic compounds. - Vol.4: Obaculactone-Zymosterol. - New York, 1953. - pp. 107-108
  3. Hall D.G. Boronic Acids, 2005. - pp. 10
  4. Lewis R.J. Sax's Dangerous Properties of Industrial Materials. - 11ed. - Wiley-interscience, 2004. - pp. 361
  5. Кочешков К.А., Несмеянов А.Н. Синтетические методы в области металлорганических соединений элементов 3 группы. - М.-Л.: ИАН СССР, 1945. - pp. 42 [Russian]
  6. Краткая химическая энциклопедия. - Т. 1: А-Е. - М.: Советская энциклопедия, 1961. - pp. 461 [Russian]
  7. Справочник химика. - Т. 2. - Л.-М.: Химия, 1964. - pp. 538-539 [Russian]
  8. Справочник химика. - Т. 3. - М.-Л.: Химия, 1965. - pp. 95 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru