Assignment #2: Article summary

I'm doing my research paper on the synthesis of teflon, tracing back the historical roots of the molecule and the different ways in which teflon has been synthesized since it's first discovery. I will mention the significance of the molecule in terms of all of the applications beyond nonstick cookware, such as biomedicine.

The present summary will be on the following article:
"Polytetrafluoroethylene" W.E. Hanford and R.M. Joyce. Journal of the American Chemical Society. 68, 2082 (1946)
[Full Marks JCB]
http://dx.doi.org/10.1021/ja01214a062

Introduction

Paragraph 1: The first paragraph briefly states that Plunkett first discovered polytetrafluoroethlyene, a molecule that possesses unusual properties and is chemically inert, owing to the fact that it is a fluorinated, saturated organic compound. The last sentence states what the paper is going to discuss: a new, improved way of preparing polytetrafluoroethlyene as well as information about the molecule's physical properties.

Paragraph 2: This paragraph states that polytetrafluoroethlyene was first characterized by two authors: Ruff and Bretschneider. They prepared it from tetrafluoromethane while another group prepared it by the dechlorination of sym-dichlorotetrafluoroethane.



Polymerization
Paragraph 3: This paragraph briefly describes the first polymerization of tetrafluoroethlyene and how a more controllable polymerization procedure was developed utilizing superatmospheric pressure in the presence of water and polymerization initiators, such as ammonium, sodium, or potassium persulfates.

Paragraph 4: [This paragraph is the first of two paragraphs detailing the method of polymerization of tetrafluorethylene]. The paragraph details how a dilute solution of hydrogen peroxide is loaded into a silver-lined pressure bomb followed by "evacuation" of gas so that tetrafluoroethylene can be loaded. Then, the mixture is heated and agitated and then allowed to cool before the polymer is separated from the aqueous phase by filtration.

Paragraph 5: [This paragraph is the second of two paragraphs detailing the method of polymerization of tetrafluorethylene]. The paragraph details the methods of controlling the polymerization reaction as well as ways in which to mitigate hazards associated with the polymerization of tetrafluorethylene: 1) control temperature, use adequate cooling facilities, provide sufficient agitation, and control pressure of reacton in order to prevent the explosive decomposition of the monomer.



Properties of Polytetrafluoroehtylene
Paragraph 6: This is a very long paragraph describing the properties of polytetrafluoroethlyene: it is a highly crystaline linear polymer as evidenced by a) X-ray diffraction patterns, b) the ability to form thin films that are characteristically slippery in texture, c) sharp transition temperature at 327 degrees that shift physica form from a stiff translucent material to a transparent rubbery material. Addtionally, above the transition temperature and under tensile stress, the polymer can undergo deformation and can tear or break, as a result.

Paragraph 7: This paragraph describes how chemically inert polytetrafluoroethlyene is: thermal degradation in air does not include carbonization at temperatures ranging from 450-700 degrees; it's not attacked by strong acids, even at high temperatures. It does state that molten sodium can attack polytetrafluoroethlyene at 200 degrees.

Paragraph 8: This paragraph describes how polytetrafluoroethlyene is not dissolved in organic solvents, even at elevated temperatures and that this insolubility has prevented accurate measurement of molecular weight of the polymer.

Paragraph 9: This paragraph describes how polytetrafluoroethlyene has an extremely low dielectric loss factor for a solid and goes on to describe other physical properties such as refractive index and dielectric constant.



X-Ray Diffraction
Paragraph 10: [This paragraph is the first of two paragraphs detailing the X-ray diffraction data in the paper.] This paragraph describes the X-ray diffraction images of oriented and unoriented polytetrafluoroethlyene films at various temperatures above and below the transition temperature of 327 degrees (one of the only things I could pick up from the data was that at temperatures below the critical temperature, there were oriented and unoriented X-ray diffraction images, demonstrating the cystallinity of the polymer, while at temperatures above the critical temperature there was only an unoriented image, demonstrating the lack of crystallinity.)


Paragraph 11: [This paragraph is the second of two paragraphs detailing the X-ray diffraction data in the paper.] This paragraph describes the infrared absorption spectrum of a polytetrafluoroethlyene film: there is only one major absorption band at 8-8.7 microns wavelength, indicating the strong presence of C-F bond, with weaker bands at longer wavelengths. The paragraph also attributes the lack of UV absorption to Rayleigh scattering of incident light due to the haze of the polymer film.



Transition Point
Paragraph 12 : This paragraph is a long paragraph that solely describes the transition point of polytetrafluoroethlyene: the transition temperature of 327 degrees has characteristics of a melting point due to the 1) X-ray diffraction data; 2) the polymer can't be oriented above this temperature; and 3) oriented polymers below this temperature become unoriented after heating above the transition tempearature. The paragraph also states that polytetrafluoroethlyene is different from other thermoplastics in that it does not undergo rapid plastic deformation or demonstrate significant viscous flow above its transition point temperature.


Structure and Viscosity of Polytetrafluoroethylene
Paragraph 13 : This paragraph restates the evidence that polytetrafluoroethylene is a linear polymer that is not cross-linked: 1) it has high degree of crystallinity; 2) it can be oriented, and it has a sharp transition point. The paragraph also discusses the probable structure of polytetrafluoroethylene as an unbranched monomer in the form of –(CF2CF2)-n.

Paragraph 13 : This paragraph discusses the high melt viscosity of polytetrafluoroethylene. It states that this physical characteristic is likely due to the polymer structure, such as restricted rotation of the carbon atoms in the fluorocarbon chain, rather than due to the chain length.

Paragraph 14 : This paragraph discusses how the fluorocarbon structure of polytetrafluoroethylene contributes to restricted rotation of carbon atoms: there is an electrostatic repulsion between CF2 groups, there is steric hindrance between neighboring CF2 groups due to the large size of fluorine (fluorine has almost double the atomic radius of hydrogen). Lastly, the paragraph states that because of this restriction on rotation, the polymer segments can be extremely long, necessitating very high activation energy for viscous flow.

Paragraph 15: This paragraph further discusses the high viscous flow characteristic of polytetrafluoroethylene. It re-emphasizes the fact, or idea, that the restriction of rotation of all adjacent carbons within the polymer can lead to an extremely long “statistical flow segment” which would require high activation energies above the temperature of thermal degradation of the polymer.


Cohesion

Paragraph 17: This paragraph discusses how the substituent fluorine atoms along the polymer creates a strong repulsive force that prevents interchain bonding and, as a result, the molecular cohesion between neighboring polymer molecules is very low. As a result of this low cohesion, the polymer can fracture easily above its transition temperature of 327 degrees but still, because of the strong repulsive forces of the fluorine atoms, there is little interchain bonding.


Insolubility
Paragraph 18: This paragraph contrasts polytetrafluoroethylene with polyethylene: they both are insoluble in organic solvents at room temperature; polytetrafluoroethylene remains insoluble at higher temperatures while polyethylene becomes increasingly soluble by 70 degrees. The authors attribute this insolubility of polytetrafluoroethylene to the very low forces of association between its constituent fluorocarbons and other organic compounds.


Acknowledgments
Paragraph 19: This paragraph is self-explanatory, detailing the acknowledgements of those that have made significant contributions to the paper.


Summary
Paragraph 20: This paragraph summarizes the key points of the paper: 1) an improved method of polymerizing tetrafluoroethylene; 2) the physical properties of polytetrafluoroethylene, including its high melt viscosity, insolubility in organic solvents, low dielectric loss factor, chemical inertness, and the evidence that it is a linear, unbranched crystalline fluorocarbon.












Assignment #1: 5 Properties Assignment


9/30/2010:
  1. Chose chloroform as molecule.
  2. Beillstein Query on chloroform:
Secondary Source
Primary Source (traced from Secondary)
Boiling Point
Boiling Point (Converted Value)
Link to Primary/Secondary Source
Screen shot of Source
Beilstein
Journal of American Chemical Society
334.27 K
[@760mm Hg]
61.12 C
[@101.325 Pa]
http://pubs.acs.org/doi/pdf/10.1021/ja01291a075
PRIMARY SOURCE
Chloroform_BP__1_Stedman[1].jpg
Beilstein
Journal of Chemical and Engineering Data
61.20 C
[@760mm Hg]
61.20 C
[@101.325 Pa]
http://pubs.acs.org/doi/pdf/10.1021/je60079a018
PRIMARY SOURCE
Chloroform_BP__2_stedman[1].jpg
Beilstein
Journal of Chemical and Engineering Data
334.35 K
[@101.3kPa]
61.20 C
[@101.3kPa]
http://pubs.acs.org/doi/pdf/10.1021/je950263m
PRIMARY SOURCE
Chloroform_BP__3_stedman[1].jpg
CDC [NIOSH pocket guide to chemical hazards]

143°F
[does not say at what pressure] assume 101.325Pa
62°C
http://www.cdc.gov/niosh/npg/npgd0127.html
SECONDARY SOURCE [found via Chemspider]
Chloroform_properties_CDC_NIOSH_Stedman.jpg
CDC [NIOSH pocket guide to chemical hazards]
NIOSHExperimental Data
61.2°C
[does not say at what pressure] assume 101.325Pa
61.2°C
http://www.cdc.gov/niosh/docs/2003-154/pdfs/1003.pdf
PRIMARY SOURCE (appears as actual measured data but may be duplicate of secondary source above, so will find 1 additional source)
Chloroform_properties_CDC_NIOSH_2_Stedman.jpg
The Physical and Theoretical Chemistry Laboratory
Oxford University

61°C
[does not say at what pressure] assume 101.325Pa
61°C
http://msds.chem.ox.ac.uk/CH/chloroform.html
[found via Chemspider]
http://msds.chem.ox.ac.uk/
Chloroform_properties_MSDS_Oxford_Stedman.jpg
ChemSpider


range of experimental values
http://www.chemspider.com/Chemical-Structure.5977.html
http://www.chemspider.com/RecordView.aspx?rid=d9640806-ce04-4315-bbd4-0d01f94bbfaf
Chloroform properties_CHEMspider_Stedman.tif
Sigma Aldrich


60.5-61.5 °C
SIGMA&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC
Sigma_BP.jpg


[the first link below does not link to the paper - put the doi JCB]
Secondary Source
Primary Source (traced from Secondary)
Melting Point
Melting Point (Converted Value)
Link to Primary/Secondary Source
Screen shot of Source
Beilstein
Journal of Chemical Physics
-63.5 C
-63.5 C
http://link.aip.org.ezproxy2.library.drexel.edu/link/JCPSA6/v9/i11/p794/s1
Chloroform properties_Beilstein a_Stedman.tif

Chloroform properties_Beilstein b_Stedman.tif
Beilstein
Journal of American Chemical Society
-63.2 C
-63.2 C
http://pubs.acs.org/doi/pdf/10.1021/ja01993a012
PRIMARY SOURCE
JACS_MP_.jpg
CDC [NIOSH pocket guide to chemical hazards]

-82°F
-63°C
http://www.cdc.gov/niosh/npg/npgd0127.html
SECONDARY SOURCE
Chloroform_properties_CDC_NIOSH_Stedman.jpg
CDC [NIOSH pocket guide to chemical hazards]

-63.5C
-63.5C
http://www.cdc.gov/niosh/docs/2003-154/pdfs/1003.pdf
PRIMARY SOURCE (appears as actual measured data but
may be duplicate of secondary source above, so will find 1 additional source)
Chloroform_properties_CDC_NIOSH_2_Stedman.jpg
The Physical and Theoretical Chemistry Laboratory
Oxford University

-63°C
-63°C
http://msds.chem.ox.ac.uk/CH/chloroform.html
[found via Chemspider]
SIGMA&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPECs.
chem.ox.ac.uk/|http://msdhttp://www.sigmaaldrich.com/catalog/ProductDetail.do?lang=en&N4=C7559|SIGMA&N5=SEARCH_CONCAT_
PNO|BRAND_KEY&F=SPECs.chem.ox.ac.uk/
Chloroform_properties_MSDS_Oxford_Stedman.jpg
ChemSpider


range of experimental values
http://www.chemspider.com/Chemical-Structure.5977.html
http://www.chemspider.com/RecordView.aspx?rid=d9640806-ce04-4315-bbd4-0d01f94bbfaf
Chloroform properties_CHEMspider_Stedman.tif
Sigma Aldrich


−63 °C

Sigma_MP.jpg


Secondary Source
Refractive Index
Link to Primary/Secondary Source
Screen shot of Source
wolfram alpha
1.445
http://www.wolframalpha.com/input/?i=chloroform
 Wolfram_Properties.jpg
Sigma Aldrich
1.445
http://www.sigmaaldrich.com/catalog/ProductDetail.do?lang
=en&N4=C7559|SIGMA&N5=SEARCH_CONCAT_PNO|BRAND
_KEY&F=SPEC
Sigma_RI.jpg
Alfa Aesar
1.4450
http://cheminfo2010.wikispaces.com/file/view/AlfaAesar_Properties.jpg
AlfaAesar_Properties.jpg
Chemical Land21
1.4460
http://www.chemicalland21.com/industrialchem/organic/CHLOROFORM.htm
chemicalland21_properties.jpg
Oxford MSDS
1.4459
http://msds.chem.ox.ac.uk/CH/chloroform.html
OxfordMSDS_Properties.jpg
Merck Index (Knovel link)
1.4476
extremely long link: use screen shot only
Merck_Index_Properties.jpg
CRC Handbook of chemistry and physics
1.4459
http://www.hbcpnetbase.com.ezproxy2.library.drexel.edu//articles/03_01_91.pdf#xml=http://www.hbcpnetbase.com.ezproxy2.library.drexel.edu/search/pdfHits.asp?id=03_01_91&DocId=117386&hitCount=12&hits=363092+362582+1409+1307+1076+1075+978+871+837+762+761+193+

[SEE PAGE 492 for chloroform]

Chloroform_CRC_properties.jpg


Secondary Source
Vapor Pressure
Link to Primary/Secondary Source
Screen shot of Source
wolfram alpha
160 mmHg
http://www.wolframalpha.com/input/?i=chloroform
 Wolfram_Properties.jpg
Sigma Aldrich
160 mmHg ( 20 °C)
http://www.sigmaaldrich.com/catalog/ProductDetail.do
?lang=en&N4=C7559|SIGMA&N5=SEARCH_CONCAT
_PNO|BRAND_KEY&F=SPEC
Sigma_VP.jpg
Oxford MSDS
159 mm Hg at 20 C
http://msds.chem.ox.ac.uk/CH/chloroform.html
OxfordMSDS_Properties.jpg
INCHEM
21.2kPa at 20°C = 159 mm Hg
http://www.inchem.org/documents/icsc/icsc/eics0027.htm
INCHEM_Properties.jpg
Scorecard (pollution
information site)
159 mm Hg at 20 oC
http://www.scorecard.org/chemical-profiles/html/chloroform.html
scorecard_Properties.jpg
Engineers
Edge site
30kPa at 20°C = 225 mm Hg
http://www.engineersedge.com/fluid_flow/fluid_data.htm
engineers_edge_Properties.jpg


Secondary Source
Specific Gravity
Link to Primary/Secondary Source
Screen shot of Source
CDC [NIOSH pocket guide to chemical hazards]
1.48
http://www.cdc.gov/niosh/npg/npgd0127.html
Chloroform_properties_CDC_NIOSH_Stedman.jpg
INCHEM
1.48
http://www.inchem.org/documents/icsc/icsc/eics0027.htm
INCHEM_Properties.jpg
Oxford MSDS
1.48 g cm3
http://msds.chem.ox.ac.uk/CH/chloroform.html
OxfordMSDS_Properties.jpg
Cameochemicals
1.4832 at 68.0 ° F
http://cameochemicals.noaa.gov/chemical/2893
cameochemicals_Properties.jpg
Hawley Condensed chemical
dictionary (Knovel link)
1.485 at 20 ° C
link too long
Hawleys_Properties.jpg


Secondary Source
Density
Link to Primary/Secondary Source
Screen shot of Source
wolfram alpha
1.492 g/cm^3 = 1.492 g/ml
http://www.wolframalpha.com/input/?i=chloroform
 Chloroform_WolframAlpha_Stedman.jpg
Sigma Aldrich
1.492 g/mL at 25 °C
http://www.sigmaaldrich.com/catalog/ProductDetail
.do?lang=en&N4=C7559|SIGMA&N5=SEARCH_CONCAT
_PNO|BRAND_KEY&F=SPEC
Sigma_Density.jpg
Alfa Aesar
1.492 ??units [most likely g/ml or g/cm^3]
http://cheminfo2010.wikispaces.com/file/view/AlfaAesar_Properties.jpg
AlfaAesar_Properties.jpg
CRC Handbook of chemistry and physics
1.4788 g/cm^3= 1.4788 g/ml at 25 °C
http://www.hbcpnetbase.com.ezproxy2.library.drexel.edu//articles/03_01_91.pdf#xml=http://www.hbcpnetbase.com.ezproxy2.library.drexel.edu/search/pdfHits.asp?id=03_01_91&DocId=117386&hitCount=12&hits=363092+362582+1409+1307+1076+1075+978+871+837+762+761+193+

[SEE PAGE 492 for chloroform]

Chloroform_CRC_properties.jpg
Engineers Edge site
1.489 Kg/liter = 1.489 g/ml]
http://www.engineersedge.com/fluid_flow/fluid_data.htm
engineers_edge_Properties.jpg



Secondary Source
Flash Point
Link to Primary/Secondary Source
Screen shot of Source
wolfram alpha
-22 °C

 Wolfram_Properties2.jpg
Sigma Aldrich



Chemical Land21
"practically not flammable"
http://www.chemicalland21.com/industrialchem/organic/CHLOROFORM.htm
chemicalland21_properties.jpg
Cameochemicals
none
http://cameochemicals.noaa.gov/chemical/2893
cameochemicals_Properties.jpg
Oxford MSDS
none
http://msds.chem.ox.ac.uk/CH/chloroform.html
OxfordMSDS_Properties.jpg





Secondary Source
Vapor Density
Link to Primary/Secondary Source
Screen shot of Source
Oxford MSDS
4.1
http://msds.chem.ox.ac.uk/CH/chloroform.html
OxfordMSDS_Properties.jpg
INCHEM
4.12
http://www.inchem.org/documents/icsc/icsc/eics0027.htm
INCHEM_Properties.jpg