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13 07 2008

Carbon and All of its Forms – Retained Links on ChemSpider

Posted by: Antony Williams in ChemSpider Chemistry, Community Building, How ChemSpider Runs

Copyright©2008 Antony Williams

When we started building ChemSpider we focused initially on building the data model around “organic structures”. We always knew that we would need to deal with rather regular collisions such as inability to handle polymers, organometallic representations, allotropes and so on. Nevertheless, we move forward. Information is aggregated from multiple sources and we remove semantically linked back to the originating sources for users to check if they deem it necessary.

Carbon is a challenge. Check out the record and the identifiers will list carbon, graphite, diamond, carbon nanotubes to name just a few. Clearly the physical properties of these materials will differ. We are capturing this information. Click on the hyperlink at the end of each of the appearance data

  • Appearance: very hard crystals or light green powder

  • Appearance: soft dark grey solid

  • Appearance: grey to black powder

  • Appearance: grey solid

Now, what’s missing is the NAME of the associated form: diamond, graphite, nanotubes etc. If you hover the cursor over the hyperlink pointer you will see the title of the article and this can help identify the form IF it’s in the title. That won’t always be the case. So, we’ll be adding our Wiki capabilities to enable annotation of the properties…

The full User Data for Carbon are listed below…it’s quite extensive AND linked to original sources.

  • experimental physchem properties
    • Melting Point: ca. 3750 (sublimes)

    • Melting Point: 3727 C

    • Melting Point: 3650 C

    • Melting Point: 3652 C

    • Boiling Point: Sublimes

    • Boiling Point: ca. 5000 C

    • Boiling Point: 4200 C

    • Specific Gravity: 1.8-2.1

    • Solubility: Insoluble

    • Vapor Pressure: 0 mmHg (approx)

  • miscellaneous
    • Appearance: Black, odorless solid.

    • Appearance: very hard crystals or light green powder

    • Appearance: soft dark grey solid

    • Appearance: grey to black powder

    • Appearance: grey solid

    • Appearance: finely divided black dust or powder

    • Stability: Stable. In the form of powder reacts vigorously with a wide variety ofmaterials; in the rod form is relatively inert.

    • Stability: Stable. Incompatible with strong oxidizing agents. Combustible.Highly flammable in powdered form.

    • Stability: Stable. Combustible.

    • Toxicity: IVN-MUS LD50 440 mg kg-1

    • Safety: FLAMMABLE

    • Safety: FLAMMABLE

    • Safety: FLAMMABLE / IRRITANT

    • Safety: Minimize exposure.

    • Safety: Avoid exposure to dust. If machining or cutting, do soin an area with good ventilation.

    • Safety: Safety glasses if working with powdered carbon.

    • First Aid: Eye: Irrigate promptly Breathing: Fresh air

    • Exposure Routes: inhalation, skin and/or eye contact

    • Symptoms: Cough; irritation eyes; in presence of polycyclic aromatic hydrocarbons: [potential occupational carcinogen]

    • Target Organs: respiratory system, eyes Cancer Site [lymphatic cancer (in presence of PAHs)]

    • Incompatibilities and Reactivities: Strong oxidizers such as chlorates, bromates & nitrates

    • Personal protection and Sanitation: Skin: No recommendation Eyes: Prevent eye contact Wash skin: Daily Remove: No recommendation Change: No recommendation

    • Exposure Limits: NIOSH REL : TWA 3.5 mg/m 3 Ca TWA 0.1 mg PAHs/m 3 [Carbon black in presence of polycyclic aromatic hydrocarbons (PAHs)] See Appendix A See Appendix C OSHA PEL : TWA 3.5 mg/m3
Stumble it!

This entry was posted on Sunday, July 13th, 2008 at 8:34 am and is filed under ChemSpider Chemistry, Community Building, How ChemSpider Runs. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

One Response to “Carbon and All of its Forms – Retained Links on ChemSpider”

  1. Soaring Bear says:
    July 22nd, 2008 at 12:19 am

    Chemical polymorphism (variations in crystal packing) can affect properties as is evident in carbon (diamond, coal, nanotubes) as well as some high profile drug regulatory situations in which processing change has affected crystallization and solubility.

    From a pharmacology/activity point of view much of organic chem can live with categorizing at the connectivity level (which is part of why SMILES works most of the time). But some of it really does need to dig deeper to the stereoisomers and polymorphs. This doesn’t mean everything in the db has to go down that far in detail but that the db needs to allow for the cases that need it. So the database ought to allow a general carbon record which can point to additional records, one for each of the polymorphs.

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