Determination of the purity of hydrocarbons by measurement of freezing points

Ar, Glasgow; Aj, Streiff; Fd, Rossini

doi:10.6028/jres.035.015

Cited by 131 publications

(77 citation statements)

References 3 publications

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“…A sample of this compound, which had an original purity of 98.68 mole percent and a freezing point of 8.058° C [3], was frozen in an ice bath at 0° C. The fractional-melting tube was then placed in a 4% liter Dewar packed with ice water. This system, when insulated with glass wool, held its temperature over the weekend to within 1 deg C. The space between the walls (unsilvered in these experiments to permit visible observation) was pumped to a high vacuum to achieve a low heat transfer.…”

Section: Substances Purified By Fractional Meltingmentioning

confidence: 99%

“…T a bl e 1 giv es a s umma ry of t he fract ionatio n data. The purity values were dete rmin ed from freez in g points obtained from m elt in g cur ves [3]. This purity pattern was obtai ned on blend s of t he fractions separated from 30 experiments on fractional melting, using lOO-ml samples of tlte same s tock m ateri al of 2,5-dich.l orost)Tene [6].…”

Section: Substances Purified By Fractional Meltingmentioning

confidence: 99%

“…3 Fractional melting of a crystalline mass formed by slow equilibrium freezing is more effective than crystallization alone in separating the entire mass of the substance into its gross impuriti.es and high-purity material. A fractional-melting apparatus embracing t he above principles has been developed and successfully used for t h e past several years.…”

Section: Introductionmentioning

confidence: 99%

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Purification of substances by a process of freezing and fractional melting under equilibrium conditions

Glasgow¹,

Ross²

1956

J. RES. NATL. BUR. STAN.

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.\ purifi cation tec hnique has been developed wh ereby a mass of well -defined crystals, form ed by slow cr ystall izat ion of a liquid, . is melted under eq uilibrium co nditi ons into a seri es of fract ions. In this process the entire mass of t he s ubsta nce is fra ctio nated into its g ross impurities and high-purity material. This offers di stinct advantages over co nv ent ional fra ctional crystallization tec hniques. The apparatus prov ides for co ndu ct in g the fr actionat ing process in a closed iner t system and is well adapted for purifying co mpo unds t hat are co rrosive, toxic, or reactive with air. Details of construction and operation of the apparatus, including experim e ntal resu lts on 2,5-dichlorostyrene, ar c in cluded in t he repo rt .

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Section: Substances Purified By Fractional Meltingmentioning

confidence: 99%

Section: Substances Purified By Fractional Meltingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Purification of substances by a process of freezing and fractional melting under equilibrium conditions

Glasgow¹,

Ross²

1956

J. RES. NATL. BUR. STAN.

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“…See reference [5] for details. b A roman numeral I indicates that the value Is for that crystalline form having the bighest freezing point.…”

Section: Freezing Points and Puritymentioning

confidence: 99%

“…• The values in this column were calculated as described in reference [5], using the values of the cryoscopic constants and freezing points for zero impurity gIven in the "z" tables of the American Petroleum Institute Research Project 44, reference [6]. For the 19 compounds for which values of the freezing point for zero impurity are reported in this paper, the values given in reference [6] are, at the time of this writing, identical to those in this table.…”

Section: Freezing Points and Puritymentioning

confidence: 99%

Purification, purity, and freezing points of 31 hydrocarbons of the API-NBS series

Ar¹,

Et²

1946

J. RES. NATL. BUR. STAN.

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Compressions of liquids. III. Temperature and molecular weight dependence of the Hudleston parameters for the n‐alkanes

Doolittle¹,

Doolittle²

1960

AIChE Journal

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General equations for the temperature dependence of the parameters of the Hudleston equation are given which were deduced from a study of n-alkane compression data. Empirical expressions for the molecular-weight dependence of the constants of these equations are likewise given which are applicable only to n-alkanes. By use of these relations in the Hudleston equation the compressions of the family of liquid n-alkanes over ranges of T, P, and m were calculated on an IBM-650 computer. The over-all standard percentage error (SPE) of the computer calcufations for n-alkanes of 7 to 20 carbons up to temperatures not exceeding their normal boiling points was 0.10%. The over-all SPE for n-alkanes of 7 to 40 carbons up to temperatures substantially above their normal boiling points (but not exceeding 300°C.) was 0.21 %.Since the Hudleston ( 1 5 ) equation has been shown (8, 1 4 ) to represent pressure-volume data on liquids at constant temperature with high accuracy, it seemed desirable to investigate the temperature-dependent parameters of this equation so that it could be used as an equation of state for the purpose of making certain liquid-state thermodynamic calculations.To permit the calculation of compressions for all members of the n-alkane family, empirical equations for the molecular-weight dependence of all parameters involved were determined. These are applicable to the n-alkanes only. With all variables defined as functions of temperature and molecular weight, a trial-and-error solution of the Hudleston equation was programed for the IBM-650 computer, and a set of tables was listed giving the specific volumes of all the n-alkanes studied at their temperatures of measurement but at even pressures.The purpose of carrying out this empirical study was twofold: to determine the nature of the variation, particularly that of the temperature dependence, as a step toward a better understanding of the Iiquid state and to provide a body of compression data at even pressures for use in subsequent calculations involving the behavior of liquids.The apparatus and method used by Simon and Cornish to measure the volumes of liquids under pressure have been described ( 1 0) , and their data on eight n-alkanes of 7 to 40 carbons has been evaluated (8). It has been shown that the data for n-heptane and n-eicosane are very well represented by the Hudleston ( 1 5 ) equation. This paper considers all the Simon and Cornish data and the n-alkane data of other investigators for the purpose of establishing the temperature and molecularweight dependence of the parameters of the Hudleston equation. Dortha B. Doolittle is at the West Virginia Institute of Technology, Montgomery, West Virginia.

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Determination of the purity of hydrocarbons by measurement of freezing points

Cited by 131 publications

References 3 publications

Purification of substances by a process of freezing and fractional melting under equilibrium conditions

Purification of substances by a process of freezing and fractional melting under equilibrium conditions

Purification, purity, and freezing points of 31 hydrocarbons of the API-NBS series

Compressions of liquids. III. Temperature and molecular weight dependence of the Hudleston parameters for the n‐alkanes

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