Errors of Combustion of Compounds for C
            <sup>14</sup>
            Analysis

Armstrong, W. D.; Singer, Leon; Zbarsky, S. H.; Dunshee, Bryant R.

doi:10.1126/science.112.2914.531

Cited by 13 publications

(2 citation statements)

References 10 publications

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“…The carrier gas was purified oxygen, and the carbon dioxide was absorbed by passage through each of two 250-1111 centrifuge tubes one-third filled with aqueous barium hydroxide free of carbonate. Each tube contained a sillall magnetic stirrer to inake sure that the distribution of C14-carbon in the precipitated barium carbonate would be uniform (29), and some samples were mixed with pulverized potassium dichromate to prevent any loss of carbon dioxide as sodiunl carbonate during the combustion. The precipitated barium carbonate was recovered by centrifugation and was magnetically stirred with changes of wash water (free of carbon dioxide) and finally exchaliged into acetone, giving a fine-grained product suitable for counting.…”

Section: Consumption Of Formaldehydementioning

confidence: 99%

Condensation of Spruce Periodate Lignin With Formaldehyde

Eisenbraun¹,

Purves²

1961

Can. J. Chem.

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The use of 7 3 y 0 sulphuric acid a t 41' for 1 hour or less caused the periodate lignin t o condense with 32y0 by weight of formaldehyde, a s shown by direct measurement and by employing C1a-formaldehyde. Analyses of the product, however, suggested that the elements of water had been expelled during the condensation and that the true yield was about 120%. Up t o 106% was recovered a s material insoluble in dilute sulphuric acid (Ross-Potter lignin), and about 9% as a more soluble form. The approximate equivalence in weight of the Ross-Potter lignin t o the original periodate (or Klason) lignin thus originated in the cancellation of three large errors. Formaldehyde periodate lignin failed t o yield vanillin when oxidized in alliali with nitrobenzene or cupric hydroxide. Oxidation with alkaline potassium permanganate, or with iodic acid a t not more than 200°, yielded benzenepentacarboxylic acid and perhaps mellitic acid (total, 3.9%) but none of the 1,2,4,5-tetracarboxylic acid recovered (together with the pentacarboxylic acid) from similar oxidations of periodate lignin. Convenient semimicro-scale oxidations with cupric hydroxide and with iodic acid, and the chromatography of the benzenepenta-and -tetra-carboxylic acids on paper, were described. INTRODUCTIONI t is well kilown that the treatment of wood meal with 72y0 sulphuric acid near 20°, as in the I

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Section: Consumption Of Formaldehydementioning

confidence: 99%

Condensation of Spruce Periodate Lignin With Formaldehyde

Eisenbraun¹,

Purves²

1961

Can. J. Chem.

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“…It has been reported by W. D. Armstrong and coworkers [ 1 ] 1 that C 14 O 2 and C 12 O 2 are evolved at different rates during oxidation of organic compounds. They report that on wet combustion of xanthydrourea (using the Van Slyke-Folch oxidizing mixture), the C 14 O 2 came off to a very small extent in the first portions of reactant gasses and to a very large extent in the latter portions.…”

Section: Introductionmentioning

confidence: 99%

A carbon-14 beta-ray standard, benzoic acid-7-C-14 in toluene, for liquid scintillation counters

Marlow¹,

Medlock²

1960

J. RES. NATL. BUR. STAN. SECT. A.

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A carboll-14 beta-ray stand ard for use in liquid scintill ation coun tin g has been prep ared and stand ardized . The sample co ns ist s of benzoic aeid-7-C14 dissolved in t olu ene. Samples of th e sol ution were oxidi zed qua nt itatively in a P aar oxygen bomb, a nd the radi oactivity of t he carbon diox ide was co mpar ed wi th t he r adioactivi ty of carbon diox id e prepa red q uan titat ively from t he Bureau's sodium carb on ate-C14 stand a rd .

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Reactions of ethyl bromide and aluminium bromide. II. Isomerisation of ethyl‐[1‐¹⁴C] bromide

Sixma

Hendriks

1956

Recl. Trav. Chim. Pays‐Bas

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The isomerisation of ethyl-[ l-"C] bromide to ethyl-[ ZWC] bromide in the liquid phase is catalysed by aluminium bromide. From measurements of the reaction rate at temperatures between +25" and +50° the activation energy of this reaction appears to be 19.1 kcal/mole (2 2 %).The isomerisation of alkyl halides was first studied a long time ago *) and shortly after the discovery of the reaction of FriedeZ and Crafts it was noted that these rearrangements are catalysed by the aluminium halides. The mechanism of these isomerisation reactions under the influence of Lewis acids is of considerable interest with respect to our knowledge of the mechanism of the Friedel-Crafts alkylation.As part of a series of investigations into problems connected with the mechanism of Friedel-Crafts reactions we have investigated the isomerisation of some simple alkyl halides under the influenceof aluminium bromide. Isomerisation reactions of this type have been known since the investigations of KekuZ6 8 ) and Gustauson s) which showed that propyl bromide is isomerised readily to isopropyl bromide by the action of aluminium bromide.From later investigations it appeared that the reaction tends to an equilibrium mixture4) which at 2 6 ' for example contains 91 % of isopropyl bromide. For some time it was believed that isomerisation reactions of this type occurred by elimination and subsequent readdition of hydrogen bromide, but this hypothesis has been definitely disproved by Nash, Taylor and Doerings), who effected the rearrangement of propyl chloride to isopropyl chloride under the influence of aluminium chloride in an atmosphere of deuterium chloride and found that no hydrogen was exchanged for deuterium during the reaction.Many related isomerisation reactions have been investigated 6 ) and in more recent years the results usually have been interpreted in terms of rearrangements of carbonium ions. Reactions of ethyl bromide and aluminium bromide. 11. 75 (1956) RECUEIL 171 us to communicate some results which we obtained in our study of the reaction between ethyl bromide and aluminium bromide. Aluminium bromide readily dissolves in ethyl bromide and therefore determinations of the velocity of the isomerisation reaction are possible.The present investigation forms the first part of a series of quantitative studies of the rearrangement reactions of organic bromides under the influence of aluminium bromide. Our program involves the study of the transfer of hydride, alkyl and aryl groups and the comparison of these reactions with the rates of bromine exchange on the one hand and of the Friedel-Crafts reaction on the other.

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Errors of Combustion of Compounds for C ¹⁴ Analysis

Cited by 13 publications

References 10 publications

Condensation of Spruce Periodate Lignin With Formaldehyde

Condensation of Spruce Periodate Lignin With Formaldehyde

A carbon-14 beta-ray standard, benzoic acid-7-C-14 in toluene, for liquid scintillation counters

Reactions of ethyl bromide and aluminium bromide. II. Isomerisation of ethyl‐[1‐¹⁴C] bromide

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Errors of Combustion of Compounds for C 14 Analysis

Cited by 13 publications

References 10 publications

Condensation of Spruce Periodate Lignin With Formaldehyde

Condensation of Spruce Periodate Lignin With Formaldehyde

A carbon-14 beta-ray standard, benzoic acid-7-C-14 in toluene, for liquid scintillation counters

Reactions of ethyl bromide and aluminium bromide. II. Isomerisation of ethyl‐[1‐14C] bromide

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Errors of Combustion of Compounds for C ¹⁴ Analysis

Reactions of ethyl bromide and aluminium bromide. II. Isomerisation of ethyl‐[1‐¹⁴C] bromide