Determination of the Bond Dissociation Energy D(C2H5Hg—C2H5) by the Toluene Carrier Method

1971 ◽  
Vol 49 (20) ◽  
pp. 3367-3374 ◽  
Author(s):  
A. C. Lalonde ◽  
S. J. W. Price
Keyword(s):  
Excellent Agreement ◽  
Arrhenius Equation ◽  
Flow System ◽  
Material Balance ◽  
Partial Solution ◽  
Complete Analysis ◽  
Product Analysis ◽  
Good Material ◽  
Good Agreement

The pyrolysis of diethylmercury has been studied in a toluene carrier flow System from 601 to 673 °K using total pressures of 1.04 to 7.75 mm. The progress of the reaction was followed by measuring the amounts of unreacted alkyl. Partial solution of butane in the toluene condensed at the outlet of the reactor made full product analysis difficult. Complete analysis in a number of runs did yield a good material balance between alkyl decomposed and [Formula: see text].[Formula: see text][Formula: see text][Formula: see text][Formula: see text]The Arrhenius equation for reaction 1, log k1(s−1) = 15.4 − (45 700 ± 1 000)/2.3 RT, is in excellent agreement with that estimated by Benson and O'Neal. Based on a number of simplifying approximations, log k3(cm3mol−1s−1) = 10.9 − (9 300 ± 2 000)/2.3 RT. The estimated disproportionation to combination ratio, K5/K4 = 0.09 – 0.12 is in good agreement with earlier work.Approximate correction of E1 to absolute zero yields D(C2H5Hg—C2H5) = 43.7 kcal mol−1 and therefore by difference D(Hg—C2H5) = 6.5 kcal mol−1.

Determination of the bond dissociation energy, D(CH3Hg—CH3), by the toluene carrier method

1969 ◽  
Vol 47 (6) ◽  
pp. 991-994 ◽  
Author(s):  
R. J. Kominar ◽  
S. J. Price
Keyword(s):  
Thermal Decomposition ◽  
Excellent Agreement ◽  
Rate Constant ◽  
Pressure Range ◽  
Arrhenius Equation ◽  
Flow System ◽  
Methyl Radicals ◽  
Exponential Factors ◽  
Pressure Independent

The thermal decomposition of Hg(CH3)2 has been studied in a toluene carrier flow system over the pressure range 4.5 to 323 mm at temperatures of 422 to 527 °C. The Arrhenius equation for the pressure independent region,[Formula: see text]is in excellent agreement with earlier work on the fully inhibited decomposition at lower temperatures. The region of fall off of the unimolecular rate constant is in agreement with a classical Kassel calculation using s = 16−18, but the rate of fall off requires the use of a curve with s = 3, displaced five log units to the left. This is consistent with the previous results for the dissociation of ethane into two methyl radicals and is further evidence of the inability of the classical Kassel equation to represent the behavior of systems with high pre-exponential factors.

Automated Atomic Absorption Spectrophotometry

1967 ◽  
Vol 13 (9) ◽  
pp. 797-805 ◽  
Author(s):  
Bernard Klein ◽  
James H Kaufman ◽  
Morris Oklander
Keyword(s):  
Atomic Absorption ◽  
Flow System ◽  
Atomic Absorption Spectrophotometry ◽  
Spinal Fluid ◽  
Absorption Spectrophotometry ◽  
Comparison Of Results ◽  
Urine Specimens ◽  
Good Agreement

Abstract A simplified flow system is presented for the determination of calcium in urine and spinal fluid, by automated atomic absorption spectrophotometry (AAS). Analysis following the addition of calcium to urine or spinal fluid specimens showed a mean recovery of 103% and 99%, respectively. A comparison of results of analyses on unselected urine specimens by manual and automated AAS shows good agreement.

Squaraine chemistry. Synthesis of bis(4-dimethylaminophenyl)squaraine from dialkyl squarates. Mechanism and scope of the synthesis

1986 ◽  
Vol 64 (12) ◽  
pp. 2267-2273 ◽  
Author(s):  
Kock-Yee Law ◽  
F. Court Bailey
Keyword(s):  
Steric Effect ◽  
Alkyl Chain ◽  
Material Balance ◽  
Squaric Acid ◽  
Side Reactions ◽  
Key Factors ◽  
Product Analysis ◽  
Good Material ◽  
Two Factors ◽  
Optimized Conditions

The mechanism and the scope of the synthesis of bis(4-dialkylaminoaryl)squaraines from di-n-butyl squarate and N,N-dialkylanilines have been studied. Results show that water and acid are key factors of the synthesis, and these two factors have been optimized. Yields of squaraine are also found to be sensitive to the steric effect provided by the alkyl chain in dialkyl squarates as well as to the concentration of the aniline reagent used in the synthesis. Mechanistic results suggest that alkyl squarate is the precursor of the synthesis, and that squaraine is formed by diarylation of alkyl squarate with an N,N-dialkylaniline derivative. Under optimized conditions, a number of squaraines have been synthesized. Yields, which are comparable to those synthesized from squaric acid, are obtained. Product analysis with good material balance has been achieved, and results show that arylation and diarylation of the starting di-n-butyl squarate are major side reactions in the squaraine synthesis.

Determination of Serum Calcium by Automated Atomic Absorption Spectroscopy

1967 ◽  
Vol 13 (5) ◽  
pp. 388-396 ◽  
Author(s):  
Bernard Klein ◽  
James H Kaufman ◽  
Stanley Morgenstern
Keyword(s):  
Hydrochloric Acid ◽  
Atomic Absorption ◽  
Serum Calcium ◽  
Flow System ◽  
Atomic Absorption Spectrophotometry ◽  
Absorption Spectrophotometry ◽  
Comparison Of The Results ◽  
Automated Determination ◽  
Good Agreement

Abstract A procedure is presented for the automated determination of serum calcium by atomic absorption spectrophotometry. The serum sample, diluted with acidified lanthanum dichloride, is dialyzed against 0.1 N hydrochloric acid and a portion of the recipient solution is pumped into the atomizer-burner of the spectrophotometer. Data are presented on the precision and reproducibility of the flow system. Addition of calcium to serum shows a mean recovery of 99%. A comparison of the results of analyses on random specimens by permanganate titration and the automated procedure shows good agreement.

Determination of Conditions for the Suppression of CH3 + Sb(CH3)2→Sb(CH3)3 and Evaluation of D[(CH3)2Sb—CH3]

1972 ◽  
Vol 50 (7) ◽  
pp. 966-971 ◽  
Author(s):  
S. J. W. Price ◽  
J. P. Richard
Keyword(s):  
Activation Energy ◽  
Least Squares ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of trimethylantimony has been studied in a toluene carrier flow system over the temperature range 690–803 °K (total pressures 3.6–173.4 mm, contact times 1.0–13.5 s, decomposition 3.9–89.5%). The progress of the reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. In 23 runs the undecomposed alkyl was also determined. The quantity found was in agreement with that expected from the product analysis if three methyl radicals are released for each molecule undergoing reaction. No heterogeneous reaction was detected.Deuterium labeling led to the conclusion that regeneration of the parent alkyl occurred during the course of the decomposition. This regeneration reaction was effectively eliminated by working at toluene pressures above 150 mm. Least squares analysis of the results obtained under conditions where regeneration should not be important givenLog10k/s−1 = 15.33 − (55 900 ± 1 000)/2.3RTThe activation energy should be a good approximation to D[(CH3)2Sb—CH3].Significant decomposition of SbCH3 probably does not occur. It seems most likely that free Sb is formed via 2Sb(CH3) → Sb(CH3)2 + Sb.

Modification of AOAC Method for Determination of Soluble Solids in Tomato Products

1972 ◽  
Vol 55 (4) ◽  
pp. 809-810
Author(s):  
Frank C Lamb
Keyword(s):  
Sample Preparation ◽  
Excellent Agreement ◽  
Soluble Solids ◽  
Official Method ◽  
Aoac Method ◽  
Centrifugation Technique ◽  
Tomato Products ◽  
Good Agreement

Abstract The official first action method for soluble solids in tomato products, 32.008–32.010, was modified to permit the optional use of an ultracentrifuge to prepare samples for readings in a refractometer. Excellent agreement was obtained between the official method which specifies filtration and the centrifugation technique. Good agreement was also obtained between 2 laboratories using the centrifugation technique. The official method was modified to include the optional use of an ultracentrifuge for sample preparation.

Determination of D[C6F5CH2—Br] by the toluene carrier method

1980 ◽  
Vol 58 (18) ◽  
pp. 1906-1908 ◽  
Author(s):  
R. John Kominar ◽  
Michael J. Krech ◽  
Stanley James W. Price
Keyword(s):  
Arrhenius Equation ◽  
Parent Compound ◽  
Material Balance ◽  
Internal Standard ◽  
Standard Technique ◽  
The Other ◽  
Reasonable Estimate ◽  
First Order ◽  
A Value

The pyrolysis of C6F5CH2Br has been studied by the toluene carrier technique over the temperature range 727–800 °C. Rate constants are based on analysis for residual parent compound by gas chromatography using an internal standard technique. In selected runs a material balance of 100 ± 2% was obtained for bromine based on C6F5CH2Br plus HBr. Within the limits of the experimental technique the process appears to be first order and homogeneous. In addition to HBr the other major products of the thermal decomposition are C6F5CH3, (C6F5CH2)2, C6F5CH2CH2C6H5, and (C6H5CH2)2. The Arrhenius equation obtained is[Formula: see text]The log A value is very close to the value of 14.6 recommended by Benson and O'Neal for the decomposition of C6H5CH2Br. The activation energy, 225 ± 6 kJ mol−1, should be a reasonable estimate of D[C6F5CH2—Br].

Determination of D[(CH3)3Pb—CH3] by the Toluene Carrier Method

1972 ◽  
Vol 50 (16) ◽  
pp. 2639-2641 ◽  
Author(s):  
K. M. Gilroy ◽  
S. J. Price ◽  
N. J. Webster
Keyword(s):  
Least Squares ◽  
Flow System ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Method Of Least Squares ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of tetramethyl lead has been studied in a toluene carrier flow system over the temperature range 671–753 °K (contact times 0.72–1.67 s, 3–77% decomposition). The reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. Comparison of the extent of reaction based on product analysis and on alkyl recovery indicates that approximately four methyl radicals are released for each molecule undergoing reaction 1.[Formula: see text]The method of least squares gives k1 = 5.0 × 1014 exp (−49 400/RT) sB1 with an estimated uncertainty of ± 1 000 cal mol−1 in E1. Under the conditions used E1 should be a reasonable measure of D[(CH3)3Pb—CH3].

Automated Atomic Absorption Spectrophotometry

1967 ◽  
Vol 13 (9) ◽  
pp. 788-796 ◽  
Author(s):  
Bernard Klein ◽  
James H Kaufman ◽  
Morris Oklander
Keyword(s):  
Atomic Absorption ◽  
Excellent Agreement ◽  
Serum Calcium ◽  
Flow System ◽  
Serum Magnesium ◽  
Atomic Absorption Spectrophotometry ◽  
Absorption Spectrophotometry ◽  
Present Procedure ◽  
Comparison Of The Results

Abstract The flow system developed for the determination of serum calcium by automated atomic absorption spectrophotometry (AAS) was adapted to the determination of serum magnesium. A comparison of the results of analyses by the present procedure and by an automated fluorometric procedure on identical serum specimens shows excellent agreement.

COMPARATIVE ACTION OF VARIOUS OESTROGENIC COMPOUNDS ON MOUSE VAGINAL SIALIC ACIDS (II)

1969 ◽  
Vol 62 (4) ◽  
pp. 663-670 ◽  
Author(s):  
Lars Carlborg
Keyword(s):  
Sialic Acid ◽  
Response Curve ◽  
Sialic Acids ◽  
Clear Cut ◽  
Suitable Parameter ◽  
Sufficient Degree ◽  
Comparative Action ◽  
Relative Potencies ◽  
Good Agreement

ABSTRACT Oestrogens administered in lower doses than necessary to induce full cornification of the mouse vagina induce mucification. It was shown previously that the degree of mucification could be estimated by quantitative determination of sialic acids. A suitable parameter for oestrogen assay was the measurement of vaginal sialic acid concentration which exhibited a clear cut dose response curve. Eleven assays of various oestrogens were performed with this method. Their estimated relative potencies were in good agreement with other routine oestrogen assays. A statistically sufficient degree of precision was found. The sensitivity was of the same order, or slightly higher, than the Allen-Doisy test.

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