Sample Stability: A Suggested Definition and Medthod of Determination

1976 ◽  
Vol 22 (12) ◽  
pp. 2045-2045
Author(s):  
Ralph E Thiers ◽  
Gaw T wu ◽  
Allen H Reed ◽  
Lawrence K Oliver
Keyword(s):  
Double Bond ◽  
Membered Ring ◽  
Double Bonds ◽  
Test Statistic ◽  
Original Magnification ◽  
Letter To The Editor ◽  
Sample Stability ◽  
Single Bonds

Abstract Volume 22 p 52, colunm 1: In two palces, "γ-GT/ml" should read "γ-GT/CC." In Figures 2 through 4 in this paper, the "X800" in the legend refers to the original magnification. p 179: In Table 2, in the —20 °C experiment, the "test statistic" of samples 5 through 18 should be more negative by 0.5 and that of sample 24 should be —7.0 rather then —5.0. These change do not affect the conclusions. p 197, column 1: In the first full paragraph, reference "(2)" should read "(21)." p 777: In Figure 1, structures B and C should not contain an endocyclic double bond (structure A is correct)-i.e., the double bonds at the tops of the seven membered ring should be single bonds. p 833: Corrections to this Table are detailed in a Letter to the Editor, p 1751, q.v. p 1324: The drawing for Figure 2 has been interchanged with the drawing in the upper half of Figure 9, p 1327. p 1427: Richard S. Schifreen should be listed as an author. p 1745, column 1: The [3H]cortisl belongs to ref. 1, and was not supplied by Diagnostic Products Corp. p 1751, column 3, first paragraph: 9.7 mg/liter should read 0.7 mg/liter.

The Change in the Raman Spectra of Chloroprene and Isoprene in the Polymerization Process

1943 ◽  
Vol 16 (4) ◽  
pp. 841-847
Author(s):  
A. Gantmacher ◽  
S. Medvedev
Keyword(s):  
Raman Spectrum ◽  
Double Bond ◽  
Raman Spectra ◽  
Polymer Molecule ◽  
Polymerization Process ◽  
High Polymer ◽  
Single Bond ◽  
Double Bonds ◽  
Continuous Background ◽  
Single Bonds

Abstract 1. When chloroprene and isoprene polymerize, besides the frequency characterizing the conjugate double bond in the monomer, there appears a higher frequency corresponding to the isolated double bond in the polymer. In the polymerization process, the intensity of the frequency of the conjugate double bond decreases and the intensity of the frequency of the isolated double bond increases. Because of the increase in the number of single bonds in the polymer, the intensity of the frequency of the single bond 1005 in the polymer is considerably greater than in the monomer. 2. Even in the case of the samples with high polymer contents (greater than 50 per cent), the intensity of the frequency of the conjugate double bond is considerably greater than the intensity of the frequency of the isolated double bond. This is attributable to the fact that part of double bonds disappear during polymerization. 3. The Raman spectra of the chloroprene and isoprene polymers differ essentially from those of the monomers. To characterize the frequencies of vibration in the polymer molecule, it is essential to investigate its Raman spectrum in a medium free of the monomer. 4. The formation of highly polymeric molecules on polymerization does not result in an increase in the intensity of the continuous background in spectrograms.

On the π-Electron Content of Bonds and Rings in Benzenoid Hydrocarbons

2004 ◽  
Vol 59 (4-5) ◽  
pp. 295-298 ◽  
Author(s):  
Ivan Gutman ◽  
Tetsuo Morikawa ◽  
Susumu Narita
Keyword(s):  
Bond Order ◽  
Membered Ring ◽  
Electron Content ◽  
Bond Orders ◽  
Double Bonds ◽  
Benzenoid Hydrocarbons ◽  
Carbon Bond ◽  
Carbon Carbon Bond ◽  
Carbon Carbon Bonds ◽  
Single Bonds

The Pauling bond order can be viewed as a measure of the π-electron content of the respective carbon-carbon bond. In benzenoid hydrocarbons its values lie between 0 (in the case of essential single bonds) and 1 (in the case of essential double bonds). If the benzenoid molecule does not possess essential single and double bonds, then the Pauling bond orders are greater than 0 and less than 1, but may assume values arbitrarily close to 0 and 1. The π-electron content of a ring is equal to the sum of the π-electron contents of the carbon-carbon bonds forming this ring. We show that in benzenoid hydrocarbons the π-electron content of any (six-membered) ring lies between 0 and 5.5. If the molecule does not possess essential single and double bonds, then the π-electron content of any ring is greater than 0 and less than 5.5, but may assume values arbitrarily close to 0 and 5.5.

Chemical Reactions during Vulcanization. III

1942 ◽  
Vol 15 (3) ◽  
pp. 560-571
Author(s):  
E. A. Hauser ◽  
M. C. Sze
Keyword(s):  
Zinc Oxide ◽  
Double Bond ◽  
Chemical Reactions ◽  
Eleostearic Acid ◽  
Chemical Change ◽  
Membered Ring ◽  
Double Bonds ◽  
Tung Oil ◽  
Rate Of Reaction ◽  
Preceding Discussion

Abstract From the preceding discussion the following conclusions may be drawn: A. Vulcanization with Sulfur in General 1. Vulcanization with sulfur is fundamentally a chemical change involving activated sulfur and organic double bonds. 2. Sulfur must decompose from S8 (in the form of an eight-membered ring) to smaller molecular units, perhaps to S2 and S1 before it can be activated and react. 3. The ratio of atoms of sulfur combined to the number of double bonds lost is not restricted to one atom of sulfur for each double bond, but may have other values, which depend on the conditions and the reactions involved. B. Factice Formation 1. The rate of reaction of sulfur with tung and linseed oils is greatly influenced by small proportions of such agents as zinc oxide and mercaptobenzothiazole. 2. Combination of sulfur with the conjugated double bonds of the eleostearic acid in tung oil takes place at the terminal carbon atoms of the conjugated system, giving a typical 1,6-addition. 3. The following possible chemical reactions explain adequately the process of factice formation from tung and lineseed oil. Under different conditions different reactions predominate.

scholarly journals THE STEREOSELECTIVE ADDITION OF DIHALOCARBENES TO cistrans, trans-CYCLODODECA-1,5,9-TRIENE AND THE SYNTHESIS OF CYCLOTRIDECANONE

1966 ◽  
Vol 44 (9) ◽  
pp. 1021-1026 ◽  
Author(s):  
H. Nozaki ◽  
S. Katô ◽  
R. Noyori
Keyword(s):  
Double Bond ◽  
Membered Ring ◽  
Ring Cleavage ◽  
Addition Reactions ◽  
Double Bonds ◽  
Olefinic Bond ◽  
Stereoselective Addition

The addition reactions of dibromo- and dichloro-carbenes to cis,trans,trans-cyclododeca-1,5,9-triene (I) followed a stereoselective scheme analogous to that of other reagents forming a three-membered ring on addition to an olefinic bond. The carbenes attacked preferentially one of the trans double bonds of I and then added to the cis double bond of the resulting bicyclic cis,trans dienes. Skattebøl's ring cleavage of dihalocarbene adducts of cis-cyclo-dodecene as well as of the monoadducts of I, followed by several steps, gave cyclotridecanone in fairly good yields.

MNDO CI study of the photoisomerization of pentadieniminium

1990 ◽  
Vol 55 (12) ◽  
pp. 2874-2879 ◽  
Author(s):  
Peter Ertl
Keyword(s):  
Schiff Base ◽  
Double Bond ◽  
Configuration Interaction ◽  
Mndo Method ◽  
Double Bonds

Photoisomerization mechanism in model retinal-like protonated Schiff base pentadieniminium was investigated by using MNDO method with configuration interaction. Isomerizations around various double bonds were studied and twisted biradical geometries in S0 and S1 states were optimized. Photoisomerization proceeds exclusively around the central double bond where the twisted S1 state is strongly stabilized and the S0-S1 gap is minimal.

A stereospecific synthesis of trisubstituted double bonds

1970 ◽  
Vol 23 (4) ◽  
pp. 813 ◽  
Author(s):  
AJ Birch ◽  
B McKague
Keyword(s):  
Double Bond ◽  
Stereospecific Synthesis ◽  
Considerable Proportion ◽  
Double Bonds ◽  
Steric Configuration

An aspect of the synthesis of sterically defined trisubstituted double bonds is discussed. Metal-ammonia reductions of hydropyridinium salts such as (1 ; R, R' = H or Me) result in allylic fissions, with a considerable proportion of double bond retention in its original situation and complete retention of the original steric configuration in that position.

Chlorination of Natural Rubber in Solution with Gaseous Chlorine

1953 ◽  
Vol 26 (4) ◽  
pp. 902-911 ◽  
Author(s):  
C. S. Ramakrishnan ◽  
D. Raghunath ◽  
J. B. Pande
Keyword(s):  
Double Bond ◽  
Natural Rubber ◽  
Cyclization Reaction ◽  
Double Bonds ◽  
Chlorine Atoms ◽  
Reaction Stage ◽  
Stage 1 ◽  
Additive Reaction

Abstract The chlorination of rubber solutions by gaseous chlorine was followed by isolating the partially chlorinated products and preparing their ozonides. The ozonides were hydrolyzed, and the acids and aldehydes formed on hydrolysis were determined. By a comparison with the amounts of acids and aldehydes obtained from ozonides of unreacted rubber, the amount of residual isoprenic double bonds present was found. The loss of double bonds attending the introduction of chlorine atoms into the molecule of rubber indicates four definite stages in chlorination : (1) initial substitutive attack by chlorine, with concomitant cyclization, resulting in a loss of one double bond between two isoprenic units, (2) substitution, (3) additive reaction, and (4) essentially substitution. Chlorination of aged rubber solutions differs from the above in that the cyclization reaction (stage 1) seems to be absent.

A Novel Class of Rigid-rod Perylene Diimides and Isoindigo Semiconducting Polymers

2021 ◽  
Author(s):  
Yaping Yu ◽  
Danlei Zhu ◽  
Xiuyuan Zhu ◽  
Mahesh kumar Ravva ◽  
Jiayao Duan ◽  
...  
Keyword(s):  
Double Bond ◽  
Conjugated Polymers ◽  
Optoelectronic Properties ◽  
Semiconducting Polymers ◽  
Perylene Diimides ◽  
Rigid Rod ◽  
Single Bonds

Rigid-rod conjugated polymers contain only double-bond linkers instead of single-bonds between the monomer linkages along the backbone. These polymers exhibit exceptional optoelectronic properties and promising devices performances owing to the...

Synthese und Struktur von Cäsium-1,5-bis(p-tolyl)pentaazadienid, Cs+(tolN5tol)- / Synthesis and Structure of Cesium 1,5-Bis(p-tolyl)pentaazadienide, Cs+(tolN5tol)-

1988 ◽  
Vol 43 (5) ◽  
pp. 529-532 ◽  
Author(s):  
Raimund Schmid ◽  
Johannes Beck ◽  
Joachim Strähle
Keyword(s):  
Aqueous Solution ◽  
Zigzag Chain ◽  
Double Bonds ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Crystalline Precipitate ◽  
Concentrated Solution ◽  
Single Bonds

Cs+(tolN5tol)- (1) is formed as a yellow crystalline precipitate after addition of a concentrated aqueous solution of CsCl to a concentrated solution of 1,5-Bis(p-tolyl)pentaazadiene(1,4) in ammonia. 1 crystallizes in the orthorhombic space group Pccn with a = 3169(1), b = 434.3(2), c = 1109.4(7) pm, Z = 4. The structure contains (tolN5tol)- anions and Cs+ cations both occupying two-fold axes. The all-trans N5 zigzag chain is planar with localized double bonds N1 - N2 and N2′ - N1′ of 127.7 pm and shortened single bonds N2-N3 and N3-N2′ of 136.9 pm. The tolyl substituents are titled by 25.5° against the plane of the N atoms. Cs+ is surrounded in a square antiprismatic arrangement by eight N atoms of four N5 chains with distances Cs-N in the range of 314.6 to 366.2 pm.

Mechanisms of Nucleophilic Attack at Carbon Nitrogen Double-Bonds: The Reaction of Benzohydrazonoyl Halides With Amines

1987 ◽  
Vol 40 (10) ◽  
pp. 1777 ◽  
Author(s):  
AF Hegarty ◽  
P Rigopoulos ◽  
JE Rowe
Keyword(s):  
Double Bond ◽  
Nucleophilic Attack ◽  
Rate Data ◽  
Double Bonds ◽  
Nitrogen Double Bond

Rate data for the reaction of a series of benzohydrazonoyl halides with pyrrolidine and butan- 1-amine at 303 K are presented. Linear Hammett plots were obtained with each amine. The mechanism of the reactions and the stereochemical outcome of these displacements at the carbon-nitrogen double bond are discussed.

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