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].

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.

scholarly journals The Pyrolysis of Tetramethyltin

1972 ◽  
Vol 50 (1) ◽  
pp. 50-54 ◽  
Author(s):  
R. P. Johnson ◽  
S. J. W. Price
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
First Order ◽  
Carrier Flow ◽  
Pressure Limit

The pyrolysis of tetramethyltin has been studied in a toluene carrier flow system from 803–941 °K using total pressures of 10.6 to 52.4 mm. Contact times varied from 0.49 to 13.8 s and the amount of decomposition from 1.35–98.7%. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed. No appreciable heterogeneous reaction was detected and the first order rates constants appear to have been determined at the high pressure limit. The quantity of undecomposed alkyl was also measured and was found to be in agreement with the product analysis if four methyl radicals are released for each molecule undergoing reaction.Least squares analysis gives[Formula: see text]with an estimated uncertainty in E of ± 1 kcal mol−1. The activation energy should be a good approximation to D[(CH3)3Sn—CH3].

The pyrolysis of trimethylarsine

1970 ◽  
Vol 48 (20) ◽  
pp. 3209-3212 ◽  
Author(s):  
S. J. W. Price ◽  
J. P. Richard
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Rate Constants ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
First Order ◽  
Carrier Flow ◽  
Pressure Limit

The pyrolysis of trimethylarsine has been studied in a toluene carrier flow system from 764 to 858 °K using total pressures from 6.35 to 35.5 mm. Contact times varied from 0.9 to 3.7 s and the amount of decomposition, from 1.2 to 73 %. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed. No heterogeneous reaction was detected and the first order rate constants appear to have been determined at approximately the high pressure limit. In seven runs the undecomposed alkyl was also measured. The quantity found was in agreement with the product analysis if three methyl radicals are released for each molecule undergoing reaction.Least squares analysis of the results gives[Formula: see text]The activation energy should be a good approximation to D[(CH3)2As—CH3]. The product analysis and the values of k4/k51/2 are consistent with the simple consecutive release of three methyl radicals but thermodynamic and kinetic considerations may preclude this possibility.

Determination of D[(C2H5)3Sn—C2H5] by the toluene carrier method and studies of the reaction of C2H5 with toluene

1976 ◽  
Vol 54 (11) ◽  
pp. 1814-1819 ◽  
Author(s):  
Mary Daly ◽  
S. James W. Price
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Total Pressure ◽  
Flow System ◽  
Pyrolysis Products ◽  
Temperature Range ◽  
Carrier Flow ◽  
Full Analysis

The thermal decomposition of tetraethyltin in a toluene carrier flow System has been studied over the temperature range 725 to 833 K and decompositions of 3.4 to 98.0%. Total pressure in all runs were in the range 0.63 to 0.90 kPa and contact times of 0.59 to 4.2 s were used.The progress of the reaction was followed by carrying out full analysis of all pyrolysis products involving the C2H5 radical, assuming that all four C2H5 groups are released. In selected runs analysis for unreacted alkyl was also performed. The agreement between the two methods indicates that reaction 1 is followed rapidly by reactions 2, 3, and 4,[Formula: see text]or alternate reactions that result in the release of all four C2H5 groups each time reaction 1 occurs. The decomposition is essentially homogeneous and[Formula: see text]or −59 340/4.58T if the activation energy is expressed in cal rather than J. Combination of present values of k5 with data from previous studies

scholarly journals Method of determining the distance to the object by analyzing its image blur

Vestnik MGSU ◽  
2015 ◽  
pp. 140-151 ◽  
Author(s):  
Aleksey Alekseevich Loktev ◽  
Daniil Alekseevich Loktev
Keyword(s):  
Least Squares ◽  
Statistical Approach ◽  
Evaluation Method ◽  
Least Squares Method ◽  
Focal Length ◽  
Error Variance ◽  
Method Of Least Squares ◽  
Automated Control ◽  
Image Blur

In modern integrated monitoring systems and systems of automated control of technological processes there are several essential algorithms and procedures for obtaining primary information about an object and its behavior. The primary information is characteristics of static and moving objects: distance, speed, position in space etc. In order to obtain such information in the present work we proposed to use photos and video detectors that could provide the system with high-quality images of the object with high resolution. In the modern systems of video monitoring and automated control there are several ways of obtaining primary data on the behaviour and state of the studied objects: a multisensor approach (stereovision), building an image perspective, the use of fixed cameras and additional lighting of the object, and a special calibration of photo or video detector.In the present paper the authors develop a method of determining the distances to objects by analyzing a series of images using depth evaluation using defocusing. This method is based on the physical effect of the dependence of the determined distance to the object on the image from the focal length or aperture of the lens. When focusing the photodetector on the object at a certain distance, the other objects both closer and farther than a focal point, form a spot of blur depending on the distance to them in terms of images. Image blur of an object can be of different nature, it may be caused by the motion of the object or the detector, by the nature of the image boundaries of the object, by the object’s aggregate state, as well as by different settings of the photo-detector (focal length, shutter speed and aperture).When calculating the diameter of the blur spot it is assumed that blur at the point occurs equally in all directions. For more precise estimates of the geometrical parameters determination of the behavior and state of the object under study a statistical approach is used to determine the individual parameters and estimate their accuracy. A statistical approach is used to evaluate the deviation of the dependence of distance from the blur from different types of standard functions (logarithmic, exponential, linear). In the statistical approach the evaluation method of least squares and the method of least modules are included, as well as the Bayesian estimation, for which it is necessary to minimize the risks under different loss functions (quadratic, rectangular, linear) with known probability density (we consider normal, lognormal, Laplace, uniform distribution). As a result of the research it was established that the error variance of a function, the parameters of which are estimated using the least squares method, will be less than the error variance of the method of least modules, that is, the evaluation method of least squares is more stable. Also the errors’ estimation when using the method of least squares is unbiased, whereas the mathematical expectation when using the method of least modules is not zero, which indicates the displacement of error estimations. Therefore it is advisable to use the least squares method in the determination of the parameters of the function.In order to smooth out the possible outliers we use the Kalman filter to process the results of the initial observations and evaluation analysis, the method of least squares and the method of least three standard modules for the functions after applying the filter with different coefficients.

Remarks on the method of least squares and its application to the determination of the solarmotion

1917 ◽  
Vol 30 ◽  
pp. 149
Author(s):  
E. S. Manson
Keyword(s):  
Least Squares ◽  
Method Of Least Squares

Spectrophotometric Determination of Atropine Sulfate in the Presence of Phenylmercury (II) Acetate

1981 ◽  
Vol 64 (4) ◽  
pp. 855-859
Author(s):  
Abdel Aziz M Wahbi ◽  
Magda Barary
Keyword(s):  
Least Squares ◽  
Spectrophotometric Determination ◽  
Spectrophotometric Method ◽  
Atropine Sulfate ◽  
Official Method ◽  
Method Of Least Squares ◽  
Orthogonal Function ◽  
Two Component ◽  
Good Agreement

Abstract Two-component spectrophotometric method of analysis using 2 wavelengths, the method of least squares using absorbances, the method using 2-orthogonal function coefficients, and the method of least squares using orthogonal function coefficients have been applied to the determination of atropine sulfate in the presence of phenylmercury (II) acetate, compounds whose spectra overlap. The first method gave erroneous results; the second method gave satisfactory results for synthetic mixtures. The fourth method was superior, especially in the presence of irrelevant absorption. It has been successfully used for determining atropine sulfate in injection solutions in which a cubic irrelevant absorption was present. Results were in good agreement with those obtained by the official method.

More precise determination of the parameters of a crystal lattice by the method of least squares

1967 ◽  
Vol 7 (1) ◽  
pp. 135-137
Author(s):  
F. A. Brusentsev ◽  
A. N. Rebenko
Keyword(s):  
Crystal Lattice ◽  
Least Squares ◽  
Precise Determination ◽  
Method Of Least Squares
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