Chemistry Commons^™

A Study Of Reaction Parameters In The Hydrogenation Of Acetic Acid By Rhenium Heptoxide Catalyst, Victor L. Mylroie

Theses and Dissertations

Rhenium oxides as well as other rhenium compounds are known to display a broad spectrum of catalytic activity,^25 being resistant to attack by acids under nonoxidizing conditions, and showing a remarkable ability to resist poisoning which is a serious limiting factor in many commonly used catalysts. Rhenium catalysts are cheaper than the platinum metals with the exception of palladium. One of the most remarkable properties of the rhenium catalyst is the ability to catalyze the hydrogenation of carboxylic acids and amides to the corresponding alcohols and amines respectively. The carboxyl group (-COOH) is notoriously difficult to reduce catalytically and most …

High Pressure, High Temperature Syntheses Of Rare Earth Diantimonides And Th₃P₄ Type Polymorphs Of Rare Earth Sesquisulfides, Normal L. Eatough

Theses and Dissertations

The rare earths form series of compounds which are known for several elements but end abruptly or undergo a change of structure at some member of the series. The diantimonides are one such series. Sb-Sb repulsion becomes stronger as the rare earth size decreases and the previously known series ended at Sm. It was felt that high pressure would overcome the Sb-Sb repulsion and allow bonding to form stable or metastable compounds not possible by ordinary techniques. Synthesis studies were carried out on mixtures of antimony with all the rare earths except Pm and with Sc and Y. The known …

The Thermodynamics (Log K, [Delta]H°, [Delta]S°, [Delta]Cp°) Of Metal Ligand Interaction In Aqueous Solution.|Ni.|P Design And Construction Of An Isothermal Titration Calorimeter.|Nii.|Pthe Interaction Of Cyanide Ion With Bivalent Nickel, Zinc, Cadmium And Mercury.|Niii.|Pthe Interaction Of Glycinate Ion With Bivalent Manganese, Iron, Cobalt, Nickel, Copper, Zinc And Cadmium, Harlin Dee Johnston

Theses and Dissertations

A new isothermal titration calorimeter has been designed to facilitate the study of heats of reaction and heats of solution at constant temperature. With this calorimeter, endothermic or exothermic processes can be studied at temperatures constant to ±0.0002°C. Heat effects are compensated by balancing the heat effect of the process taking place in the calorimeter against a variable heat and a constant cooling Peltier device. The calorimeter was tested by measuring the heat of ionization of water and the heat of dilution of aqueous HClO_4 solutions. For these systems heats were measured to an accuracy of ±0.02 calorie. Log K, …

The Effect Of Thiamine And Its Antagonists On Plasma And Tissue Lactic Dehydrogenase In Rats, Dong Hwa Park

Theses and Dissertations

The lactic dehydrogenase activity in plasma and tissues was measured in the thiamine-deprived, the oxythiamine-treated and the pyrithiamine-treated rats as well as the control rats. The lactic dehydrogenase levels of brain and kidney were significantly increased by oxythiamine treatment. The enzyme activity in heart was markedly decreased only in the thiamine-deprived rats. Unlike the above tissues, the enzyme levels in liver were decreased by 29-44 per cent in all three types of thiamine deficiency, However, the enzyme activity in plasma was significantly increased only by pyrithiamine administration. The distribution patterns of lactic dehydrogenase isozymes were electrophoretically examined in these deficiencies. …

An Investigation Of Column Efficiency And The Relationship To Liquid Phase Distribution On Ultra-Low Loaded Glass Bead Gas Chromatographic Columns, Donald G. Nyberg

Theses and Dissertations

Studies have been made of column efficiencies, extra-column effects, the liquid phase mass transfer term (C_l), and liquid phase distribution at ultra-low liquid loadings on glass bead gas-liquid chromatographic columns. The advantages of using lightly loaded columns are described in detail along with a critical evaluation of the limitations of this liquid phase reduction ad infinitum. Theories have been presented by Giddings^22,23,25,30,32 which predict the mass transfer term (C_l) as a function of two extreme liquid phase distributions. The first equation assumes 100% "capillary" liquid held at the glass bead contact points and represents a very inefficient column. This prediction …

Thermodynamics Of Metal-Ligand Interactions In Solution I. The Thermodynamics Of Metal-Cyanide Interaction ; Ii. Application Of The Entropy Titration Technique To Metal-Ligand Systems ; Iii. Log K, [Delta]H And [Delta]S Values For The Interaction Of Sulfate Ion With Metal Ions ; Iv. Interaction Of Mercuric Cyanide With Thiourea In Water-Ethanol Solvent Mixtures, Delbert J. Eatough

Theses and Dissertations

Log K values, valid at zero ionic strength are reported for the interaction in aqueous solution of CN- with Ni2+ and Hg2+ at 10°, 25° and 40°C, and with Pd2+ at 25°C. ∆H° and ∆S° values valid at zero ionic strength and 25°C are also reported for the interaction of CN- with Hg2+ and for the reaction Pd(CN)42- + CN- = Pd(CN)53-. In connection with the study of Pd2+ - CN- interaction, log K values for the hydrolysis of Pd2+ to give PqOH+ and Pd(OH)2 and an E° value for the reaction Pd(s) = Pd2+ + 2e- are reported. A …

Secondary Reactions And Partial Rate Factors In The Sulfonation Of Chlorobenzene And Toluene, Ernest Arthur Brown

Theses and Dissertations

The sulfonation of chlorobenzene, chlorobenzene-benzene, and toluene-benzene mixtures by sulfur trioxide in liquid sulfur dioxide at -12.5° C. was studied to obtain isomer distribution and relative rate data. The isomer distribution for the reaction on chlorobenzene was determined by an isotope dillution technique. Relative rate experiments were conducted by sulfonating C14 labeled benzene in competition with nonradioactive chlorobenzene and toluene and the count rate of the products was used to determine product composition. Ultraviolet spectrophotometry was also used to investigate variations in isomer distributions as a function of sulfur trioxide concentration. The apparent relative rates of sulfonation (kX/kB) as calculated …

Refinements In The Isomer Distribution And Relative Rate Of Sulfonation Of Toluene And Hydrochlorination Of Olefins With Stannic Chloride Catalyst, David George Guillot

Theses and Dissertations

The sulfonation of toluene at -12.5° C. with sulfur trioxide in liquid sulfur dioxide was found to give 10.03 ± 0.20 % ortho, 0.73 ± 0.20 % meta and 89.24 ± 0.20 % para isomers. This isomer distribution was determined by isotope dilution analysis using sulfur-35 enriched sulfur trioxide. After dilution of aliquots of the neutralized sulfonation mixture with pure sodium salts of each of the isomers prepared from the corresponding toluidines, the isomers were converted to the p-toluidine salts, purified by recrystallization, and counted by liquid scintillation counting. The relative rate of sulfonation of toluene compared to benzene was …

The Synthesis Of 4-Spiro-2-Aryloxazolines Of Potential Pharmacological Interest, Paul Waddell Collins

Theses and Dissertations

Numerous and diverse physiological actions are found among 2-oxazoline compounds. No reports of the synthesis or biological testing of 4-spiro-2-aryl-2-oxazolines were found in the literature. On the basis of the known pharmacological activities of certain aza- and diazaspirans, it was felt that 4-spiro-2-aryl-2-oxazolines should possess medicinal activity. In particular, it was reasoned that the combination in a bicyclic spiro structure of the 2-oxazoline ring with rings systems commonly found in synthetic antitussive compounds might result in active antitussive agents.

The aim of this research was the synthesis of a series· of 2-aryl-2-oxazoline-4-spirocyclopentanes and a series of 1'-methyl-2-aryl-2-oxazoline-4-spiro-4’-piperidines. Six members were …

Thermodynamics Of Proton Ionization In Aqueous Solution I. A Precision Thermometric Titration Calorimeter ; Ii. Entropy Titration : A Calorimetric Method For Equilibrium Constant Determinations ; Iii. H And S Values For Carboxylic Acid Proton Ionization At 25c ; Iv. Site Of Proton Ionization From Adenosine, Lee D. Hansen

Theses and Dissertations

The design, construction, and calibration of a precision thermometric titration calorimeter is described. This calorimeter was tested by determining the enthalpy change for ionization of water. The result, 13.34 ±0.03 kcal/mole (standard deviation), is in exact agreement with the best literature values. This standard deviation indicates that, using this calorimeter, ΔH values can be determined with an accuracy of ±0.0.5 kcal/mole. A calorimetric procedure has been developed for the, simultaneous determination of the equilibrium constant, the enthalpy change, and the entropy change for a chemical reaction from a single titration (Entropy Titration). This procedure has been tested by determining pK, …

Thermodynamics Of Charge Transfer Complexes, Reed J. Jensen

Theses and Dissertations

Charge transfer complexes were studied spectrophotometrically in the liquid state by a modified Benesi-Hildabrand method. TiCl_4 - Benzene and TiCl_4 - diphenyl ether solutions were found to form contact charge transfer complexes, that is complexes with very weak and non-directional interactions. The systems TiCl_4 - anisole and TiCl_4 - diethyl ether form complexes of the types AD and AD_2 where A stands for TiCl_4 and D stand s for the organic donor. The formation constants for the complexes were, for the TiCl_4 - anisole, K_1 = 0.077, K_2 = 0.01; and TiCl_4 - diethyl ether, K_1= 3.0, K_2 = 1.0. …

Properties Of Chlorophyll Derivatives Bonded To Polymers, Richard Grant Jensen

Theses and Dissertations

Two types of water-soluble complexes of chlorophyll a with organic polymers have been investigated: chlorophyll a coordinately bonded to poly 4-vinylpyridine and a chlorophyll derivative, Mg-chlorin e_6 phytyl methyl ester, covalently bonded to GANTREZ AN (poly (methyl vinyl ether/maleic anhydride) ). The first complex was observed upon dissolving chlorophyll a and poly 4-vinylpyridine in aqueous ethanol solutions. The Mg-chlorin e_6 diester-GANTREZ AN complex (chlorophyll a/polymer) was made by aminolysing the chlorophyll ring V with 1, 6-hexanediamine to give an intermediate product, Mg-chlorin e_6 -6-N-(6' -aminohexyl) carboxamide, phytyl methyl ester. This was attached to GANTREZ AN by linkage of the 6'-amine …

A Thermodynamic Study Of (1) Ligand Replacement Reactions And (2) The Interaction Of Hgcl[Subscript 2](Aq) With Hydroxide Ion, Ethylenediamine, Glycinate Ion, And Methylamine, Jerry Alvin Partridge

Theses and Dissertations

A method is reported for determining the species formed in solution by ligand replacement reactions. Reactions in dilute aqueous solution were studied in which the Cl^- on HgCl_2(aq) was replaced by hydroxide ion, ethylenediamine, glycinate ion, and methylamine. The species formed by the replacement reactions were established through computer analysis of pH titration data. Various reaction sequences were proposed for each system and log K values were calculated for each sequence. The selection of the correct reaction sequence for each system was based on the premise that only when the correct sequence is proposed will consistent log K values be …

Hydrogenation Of 4-Methylcinnoline, William E. Maycock

Theses and Dissertations

The rapid expansion of knowledge of cinnoline chemistry since 1941 has not included the hydrocinnolines. Not one catalytic hydrogenation of a fully aromatic cinnoline had been reported. This thesis is an effort to enlarge knowledge of this particular area of cinnoline chemistry. The work is a natural outgrowth of that done at Brigham Young University on decahydroquinoxaline, both the cis- and trans- isomers having been prepared and characterized. 4-Methylcinnoline, prepared by the method of Jacobs, et.al., was hydrogenated in neutral and acidic ethanolic solutions at 2000-3000 psig. hydrogen pressure and 100-266°. The catalysts used were 5% palladium on alumina, ruthenium …

Metabolism Of Thiamine And The Effect Of Some Antagonists, Russel M. Bender

Theses and Dissertations

To investigate the possibility that thiamine has more than one vital role in the mammalian system, it was decided to use the antagonists pyrithiamine and oxythiamine, and to utilize carbon-14 labeled compounds to more effectively study the vitamin and the above-named antagonists. To make it more effective, we felt that perhaps differences between the localization of oxythiamine and pyrithiamine could be detected in the brain. We also considered and tested the possibility that either or both of the antagonists would alter the localization of thiamine. Essentially, two procedures were used in this study. One was a counting method and the …

Evaluation Of Methods Used In The Determination Of Stability Constants Of The Thallium (Iii)-Chloride System At Twenty-Five Degrees, Nelson Kent Dalley

Theses and Dissertations

The difficulties encountered in the determination of equilibrium constants in systems with small, not directly rneasureable free ligand concentrations are discussed. These difficulties are illustrated using the determination of the formation constants of the Tl(III)-Cl- system as a specific example. Four methods are used and evaluated in this study. They are (1) the corresponding solutions method, (2) the method of Fronaeus, (3) the solubility of AgCl in Tl(III) solution method and (4) the method of Hugus. A discussion and derivation of each of these methods is given. The first three methods given and free ligand concentration data from which formation …

A Calorimetric Study Of Metal Amino Acid Complexes In Aqueous Solution. I. The Copper (Ii) Glycine System. Ii. The Nickel (Ii) Glycine, Alanine And Phenylalanine Systems, Wilbur Orme Greenhalgh

Theses and Dissertations

Calorimeter values were obtained for the standard enthalpy change for the following reactions at 10,25, and 40 degrees C.: 1. The dissaciation of the amino acid, glycine, in the zwitterion form (HA) to give the basic form (A-) and a proton. 2. The reactions of copper (II) ion with glycine to form the Cu gly+ and Cu (gly)2 complexes. 3. The reactions of nickel (II) ion with glycine and alanine to form Ni gly+, Ni (gly)2, Ni al+, and Ni (al)2 complexes. For calorimetric enthalpy calculations, the initial and final concentrations of all species in the calorimeter must be known; …

I. Preparation And Properties Of Alkyl And Aryl Substituted Thioquinazolines And Sulfoxides ; Ii. An Investigation Of The Quinazoline 3-Oxide--1,4-Benzodiazepine 4-Oxide Rearrangement, Marvin C. J. Kuchar

Theses and Dissertations

I. The quinazolines, a branch of the benzodiazine class of aromatic nitrogen hetercycles, do not occur to any great extent in naturally occurring compounds. The discovery of the antimalarial febrifugine and its structure elucidation led to the preparation and investigation of a host of new quinazolines in the search for new and more effective antimalarials. Most of the present body of information governing the quinazolines arose out of these synthetic studies. The present study has been accomplished with a four-fold purpose in mind: (1) to investigate the susceptibility of chloroquinazolines to nucleophilic displacement reactions by thiols or their salts, (2) …

Thermodynamics Of I) Metal Cyanide Coordination, Ii) Water Formation, And Iii) Metal Halide Coordination, John Dewey Hale

Theses and Dissertations

ΔH values for the formation of Ni(CN)4(aq)= have been determined calorimetrically at 25° using a simple calorimeter and a thermometric titration procedure at high and low ionic strengths, respectively. Extrapolation of these ΔH values to infinite dilution resulted in a ΔH° value of -42.7 kcal./mole. Combination of ΔH° and ΔF° values gives a ΔS° value of -5.5 e.u. for Ni(CN)4(aq)= formation. A value of +70 e.u. is calculated for the ionic entropy of Ni(CN)4(aq)=. A preliminary investigation of the Zn(CN)4(aq)= system indicated the existence of zinc cyanide complexes other than Zn(CN)4= and allowed calculation of an approximate ΔH° value of …

Molecular Addition Compounds :|Bi. Systems Of P-Dioxane With Alkyl Halides, Anisole, And Silicon Tetrachloride ; Ii. Titanium Tetrachloride Chargetransfer Complexes Of Benzene, P-Xylene, And Pseudocumene, Nolan F. Mangelson

Theses and Dissertations

Freezing-point diagrams were detennined tor a number or p-dioxane systems. The system, p-dioxane:carbon tetrachloride, was found to contain a 1:2 complex with a congruent melting point of 255.71 °K. This confirmed work reported in the literature. Solid solutions in the region between 0.0000 and 0.4796 mole fraction of p-dioxane were found in the present study. The system, p-dioxane:chloroform, was found to contain a 1:2 complex with a congruent melting point of 215.65 °K. It was determined that no other complexes formed in the solid state. This information resolved contradicting reports in the literature. The system, p-dioxane:dichloromethane, was found to contain …

Directive Effects In The Sulfonation Of Toluene ; Synthesis And Attempted Rearrangement Of Some Anilinoketones ; The Kinetics And Mechanism Of The Addition Of Bromine To Cyclohexene In Dichloromethane. Solution, John Joseph Duvall

Theses and Dissertations

The pure sodium salts of the toluenesulfonic acids were prepared by one of two ways. Both methods started with diazotization of the toluidine. In the first method, the diazonium solution was treated with sulfur dioxide and copper powder, and the resulting sulfinic acid was oxidized to the sulfonic acid with potassium permanganate. In the second method, the diazonium solution was treated with cuprous chloride and sulfur dioxide to give the sulfonyl chloride which was hydrolyzed to the sulfonate. Toluene was sulfonated by SO3 (enriched with S-35) in refluxing SO2 solution. The isotope dilution technique was used to determine the isomer …

Kinetic Investigation Of The Hydrochlorination Of Olefins In Aprotic Solvents And Sulfonation Of Idobenzene And The Selectivity Relation, Thomas Glen Davies

Theses and Dissertations

Kinetic investigation of the hydrochlorination of cyclohexene and cis-2-butene in n-heptane with SnCl4 as catalyst shows that the reaction is second order with respect to both olefin and catalyst. The specific rate constants at 25° , 0° and -23.8°C and the activation parameters were determined. Investigation of the Ga2Cl6 catalyzed hydrochlorination of cyclohexene and cis-2-butene in dichloromethane indicates that alkylation and polymerization compete with the hydrochlorination reaction in the presence of the solvent. The relative reaction rates and the isomer distribution for the sulfonation of iodobenzene by S35O3 have been determined in refluxing SO2 at -10°C. The reaction resulted in …

Sulfonation Of Chlorobenzene And The Selectivity Relation ; Bromine Addition To Cyclohexene In Dichloromethane ; Thorpe's Synthesis Of The Caged Acid, 4-Methyltricyclo[1.1.0.0[Superscript 2-4]] Butane-1,2,3-Tricarboxylic Acid, John A. Gurney

Theses and Dissertations

Aromatic sulfonation and some substitution reactions of chlorobenzene show deviations in the selectivity relation. A determination of chlorobenzene sulfonation provided the following rate ratio relative to benzene and partial rate factors: 1.0, [---] of 0.064 , mf 1.7 and pf 4. 2. Our work, Olah's nitration, Ferguson's bromination and Stock's chlorination define a new relation that can be express by adding an entropy term (A) to the selectivity relation. We determined the rate of bromine-cyclohexene addition in dichloro-methane at 0° to provide a basis for a systematic variation of solvents at low temperature. An unusual zero-order reaction was encountered. The …

Dissertation In Organic Chemistry. Part I, The Fate Of The Anilino Moiety In The Rearrangement Of Α-Anilonoketones. Part Ii, Partial Rate Factors For Sulfonation Of Bromebenzene With Sulfur Trioxide. Part Iii., Preliminary Survey On The Effect Of High Pressure On Ferrocene And Cycloöctatetraene, Jerold Carter Robertson

Theses and Dissertations

Part I. The rearrangement of α-anilinoketones was studied in an effort to determine the mode of movement of the nitrogen moiety. A crossover experiment was carried out with an equimolar mixture of 2-(4- bromoanilino)-1-(4-bromophenyl)-2-(4-methoxyphenyl) ethanone and 2-(4-chloroanilino)-1-(4-chlorophenyl) -2-(4-methoxyphenyl)ethanone with γ- picoline hydrobromide as the catalyst. The reaction product was analysed by means of a mass spectrograph. The results of the analysis indicate a crossover of the nitrogen moiety during rearrangement. This indicates that the nitrogen moiety moves in an intermolecular manner during the rearrangement. Part II. The isomer distribution from the sulfonation of bromobenzene with sulfur trioxide was determined by …

An Investigation Of Coulometric Methods Of Analysis Of 1,1-Dimethylhydrazine, David M. Creighton

Theses and Dissertations

The oxidation of 1,1-dimethylhydrazine by bromine has been studied using a coulometric method of bromine generation, and a dual intermediate system of bromide and cupric ions in solution. The system allowed over-generation of bromine and back-titration by cupric ion. The results of the investigation showed that the mechanism of oxidation is not fixed, but is a function of the concentration of bromine in the solution at any time. Additional studies have been recommended, whereby the mechanisms of the reactions may be determined.

A Thermodynamic Study Of Step-Wise Complex Formation In Several Aqueous Copper (Ii)-Amino Acid Systems, Vipin M. Kothari

Theses and Dissertations

pK_n values for step-wise dissociation of protons from the protonated ligands (glycine, α-amino isobutyric acid, sarcosine and theonine) were determined potentiometrically with a Beckman Model GS pH meter in aqueous solution at 10, 20, 30 and 40° C. Log K values for step-wise interaction of glycine, α-amino isobutyric acid, sarcosine and threonine with copper(II) ion were also determined potentiometrically with a pH meter at 10, 20, 30 and 40° C. The standard free energy of formation for the step-wise interaction of copper(II) with each of the above ligands was calculated from the values of log K. Enthalpy and entropy changes …

A Thermodynamic Study Of Complex Formation In Aqueous Solution.|Ni.|Pthe Hg(Ii)-, Zn(Ii)-, Cd(Ii)-, Ag(I)-Serine Systems.|Nii.|Pthe Hg(Ii)-, Zn(Ii)-, Cd(Ii)-, In(Iii)- Thioglycollic Acid System :|Ba Study Of The Effect Of D[Pi]-D[Pi] Bonding On These Complexes, Marriner Lee Morrell

Theses and Dissertations

Thermodynamic equilibrium constants were obtained potentiometrically using a Beckman pH meter for metal-serine and metal-thioglycolloc acid complexes to study the thermodynamic properties of the complexes and the effect of dπ - dπ bonding on the equilibrium constants. The following calculations were made: 1. The stepwise dissociation of protons from serine at 10, 20, 30, and 40°C and the stepwise dissociation of protons from thioglycollic acid at 20, 30, and 40°C. 2. The thermodynamic formation constants for Zn(II), Cd(II), Hg(II), and Ag(I) with serine at 10, 20, 30, and 40°C and at two ionic strengths. 3. The thermodynamic formation constants for …

The Influence Of Temperature And Some Other Factors On The Biological And Nonbiological Oxidation Of Chalcopyrite, Pyrite And Copper Sulfide, Ezra Revier Palmer

Theses and Dissertations

The purpose of this study was: (1) to find the effect of temperature on the wet oxidation of chalcopyrite, pyrite, and copper sulfide over the biological and nonbiological range; (2) to determine the influence of ferrous and ferric iron and free oxygen(air) on the oxidation. The sulfide minerals studied were oxidized over a range of temperatures between 25° to 75° C. The optimum biological oxidation occurred near 35° C. The nonbiological oxidation was very slow at low temperatures but increased with increasing temperature. The effect of solutions used in leaching the various sulfides over the temperature range differred. A synthetic …

Investigation Of The Platinum-Rich Portion Of The Platinum-Tantalum Phase Diagram, Bob Dean Browning

Theses and Dissertations

The Pt-Ta binary system was investigated at two isotherms;1000°C and 1500°C, and at eleven alloy compositions in the range of 50 to 100 atomic percent platinum. The alloys were examined by x-ray diffraction and metallography. Three intermetallic compounds, Pt₂Ta, Pt₃Ta, and Pt₄Ta were found to exist in this composition range. The Pt₄Ta intermetallic appeared only at the 1500°C isotherm. Platinum dissolved tantalum substitutionally to 90 atomic percent at 1500 °C and to approximately 80 atomic percent at 1000 °C.

Application Of The Quasi-Lattice Theory To The Heats Of Mixing Of Some Alcohol-Hydrocarbon Systems, Mar Lynn James

Theses and Dissertations

Values for the heats of mixing were obtained calorimetrically for the systems C2H5OH-C6H12, CH3OH-C6H6 and C2H5OH-C6H6 at 25° over the complete range of composition. Analytical equations which summarize these values are: Benzene (1) - Methanol (2) System ΔHxM = x1x2[628.4 + 365.7(x1-x2) + 521.9(x1-x2)3 + 819.8(x1-x2)4 ] Benzene (1) - Ethanol (2) System ΔHxM = x1x2[748.8 + 534.1(x1-x2) + 265.7(x1-x2)2 + 408.7(x1-x2)3 + 434.1(x1-x2)4 ] Cyclohexane (1) - Ethanol (2) System ΔHxM = x1x2[615.0 + 132.4(x1-x2) + 195.9(x1-x2)2 + 251.5(x1-x2)3 + 521.7(x1-x2)4 ] where xi is the mole fraction of component i. The experimental data were satisfactorily interpreted by a …