Notices
Results 1 to 38 of 38

Thread: Is this possible?

  1. #1 Is this possible? 
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    17
    I have some questions about a reaction chain I've come up with.
    I don't know if it is possible or if it is completely correct. The goal of the reaction is to get the oxygen atom out of carbon dioxide.

    1) CO2 + LiAlH4 ----> O=CHO<sup>-</sup>
    2) O=CHO<sup>-</sup> + H2SO4 ----> O-CH-OH
    3) O-CH-OH + CH3<sup>-</sup> ----> <sup>-</sup>O-CHOH-CH3
    4) <sup>-</sup>O-CHOH-CH3 + H2SO4 ----> [CH3-CH-(OH)2] -> O=CH-CH3 + H2O
    5) O=CH-CH3 + LiAlH4 ----> CH3-CH2-O<sup>-</sup>
    6) CH3-CH2-O<sup>-</sup> + H2SO4 ---> HO-CH2-CH3

    Step1: Reduce CO2 with LiAlH4.

    Step2: Add hydrogen atoms to form formic acid

    Step3: Add CH3<sup>-</sup>. Then we get nucleophilic substitution. The CH3<sup>-</sup> cation attacks the carbon atom in O-CH-OH

    Step4: Again add hydrogen atoms. However the resulting product is unstable because of the 2 alcohol function on the same carbon atom. These 2 function 'collapse' and water and an aldehyde are formed

    Step5 and 6: are the same as Step 1 and 2.

    It this possible?


    Reply With Quote  
     

  2.  

    Related Discussions:

     

  3. #2 Re: Is this possible? 
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by jan-pieterv
    I have some questions about a reaction chain I've come up with.
    I don't know if it is possible or if it is completely correct. The goal of the reaction is to get the oxygen atom out of carbon dioxide.

    1) CO2 + LiAlH4 ----> O=CHO<sup>-</sup>
    2) O=CHO<sup>-</sup> + H2SO4 ----> O-CH-OH
    3) O-CH-OH + CH3<sup>-</sup> ----> <sup>-</sup>O-CHOH-CH3
    4) <sup>-</sup>O-CHOH-CH3 + H2SO4 ----> [CH3-CH-(OH)2] -> O=CH-CH3 + H2O
    5) O=CH-CH3 + LiAlH4 ----> CH3-CH2-O<sup>-</sup>
    6) CH3-CH2-O<sup>-</sup> + H2SO4 ---> HO-CH2-CH3

    Step1: Reduce CO2 with LiAlH4.

    Step2: Add hydrogen atoms to form formic acid

    Step3: Add CH3<sup>-</sup>. Then we get nucleophilic substitution. The CH3<sup>-</sup> cation attacks the carbon atom in O-CH-OH

    Step4: Again add hydrogen atoms. However the resulting product is unstable because of the 2 alcohol function on the same carbon atom. These 2 function 'collapse' and water and an aldehyde are formed

    Step5 and 6: are the same as Step 1 and 2.

    It this possible?

    REPLY: Is this some sort of test ? If so what is it`s purpose ? I do not understand the purpose of your questions. It seems like some sort of exam questions to me. Are you a chemistry teacher ? If so why ask these questions in a forum such as this ? All right you got me going here. QUESTION ONE`S EQUATION IS WRITTEN INCORRECTLY. As to question 3 , CH3 is a free radical and you are going to generate a chain of free radical reactions which are unpredictable unless under controlled conditions. Quetion 2 proposed product does not conform to octet rule and is not possible for that reason. 6 does not balance.product has 1 more hydogen than reactants. 5 does not balance, product has 1 more hydrogen than reactants.6 the reactant is a free radical=unpredictable products quetion 1 does not balance. no hydrogen in reactant. There, did I pass this little test or not. ...Dr.Syntax


    Reply With Quote  
     

  4. #3 Re: Is this possible? 
    Veracity Vigilante inow's Avatar
    Join Date
    Oct 2009
    Location
    Austin, TX
    Posts
    3,499
    Quote Originally Posted by dr.syntax
    I do not understand the purpose of your questions.
    Then don't respond. We had a similar conversation elsewhere already. Let people who know the answer do the responding, otherwise (in your desire to help) you're likely to do more harm than good (further confuse a person who is already so confused that they would join a community like this to try to find an answer).


    Jan - I do not have the answers you seek, but if someone does, they will login and help you as appropriate. Take care.
    Reply With Quote  
     

  5. #4 Re: Is this possible? 
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by inow
    Quote Originally Posted by dr.syntax
    I do not understand the purpose of your questions.
    Then don't respond. We had a similar conversation elsewhere already. Let people who know the answer do the responding, otherwise (in your desire to help) you're likely to do more harm than good (further confuse a person who is already so confused that they would join a community like this to try to find an answer).


    Jan - I do not have the answers you seek, but if someone does, they will login and help you as appropriate. Take care.

    How do you manage to follow me about as you do ? What is wrong with you ? You killed the Primal debate, isn`t that enough for you. Get a life and leave me alone. UNDERSTAND THIS: You do not tell me what to do ! Not now and not ever. You are the sick one not me. I never bother you, yet you continue to harass me. What are you looking for with me ? Do you Know ? If you do know tell me what it is. ...DS
    Reply With Quote  
     

  6. #5 Re: Is this possible? 
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    17
    Quote Originally Posted by dr.syntax
    Quote Originally Posted by jan-pieterv
    I have some questions about a reaction chain I've come up with.
    I don't know if it is possible or if it is completely correct. The goal of the reaction is to get the oxygen atom out of carbon dioxide.

    1) CO2 + LiAlH4 ----> O=CHO<sup>-</sup>
    2) O=CHO<sup>-</sup> + H2SO4 ----> O-CH-OH
    3) O-CH-OH + CH3<sup>-</sup> ----> <sup>-</sup>O-CHOH-CH3
    4) <sup>-</sup>O-CHOH-CH3 + H2SO4 ----> [CH3-CH-(OH)2] -> O=CH-CH3 + H2O
    5) O=CH-CH3 + LiAlH4 ----> CH3-CH2-O<sup>-</sup>
    6) CH3-CH2-O<sup>-</sup> + H2SO4 ---> HO-CH2-CH3

    Step1: Reduce CO2 with LiAlH4.

    Step2: Add hydrogen atoms to form formic acid

    Step3: Add CH3<sup>-</sup>. Then we get nucleophilic substitution. The CH3<sup>-</sup> cation attacks the carbon atom in O-CH-OH

    Step4: Again add hydrogen atoms. However the resulting product is unstable because of the 2 alcohol function on the same carbon atom. These 2 function 'collapse' and water and an aldehyde are formed

    Step5 and 6: are the same as Step 1 and 2.

    It this possible?

    REPLY: Is this some sort of test ? If so what is it`s purpose ? I do not understand the purpose of your questions. It seems like some sort of exam questions to me. Are you a chemistry teacher ? If so why ask these questions in a forum such as this ? All right you got me going here. QUESTION ONE`S EQUATION IS WRITTEN INCORRECTLY. As to question 3 , CH3 is a free radical and you are going to generate a chain of free radical reactions which are unpredictable unless under controlled conditions. Quetion 2 proposed product does not conform to octet rule and is not possible for that reason. 6 does not balance.product has 1 more hydogen than reactants. 5 does not balance, product has 1 more hydrogen than reactants.6 the reactant is a free radical=unpredictable products quetion 1 does not balance. no hydrogen in reactant. There, did I pass this little test or not. ...Dr.Syntax
    It isn't an exam question. It's just something I've come up with and want to know if these reactions are possible.

    Ok you say that equation 1 is wrong. So I would like to know what's wrong with it.
    CH3<sup>-</sup> is an ION and not a radical. Radicals are written with a dot and not with an - .The - indicates a full negative charge so it's an ION.

    In reaction 2 i have made a typo. The product should be O=CH-OH. And the first reagent in reaction 3 should also be O=CH-OH

    And in question 1 and 5 the extra hydrogen comes from LiAlH4 which losses a hydrogen atom because it's used to create negatively charged hydrogen atoms which attack the other reagent.

    BTW: use a few line feeds. It would be a lot easier to read your response
    Reply With Quote  
     

  7. #6 Re: Is this possible? 
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by jan-pieterv
    Quote Originally Posted by dr.syntax
    Quote Originally Posted by jan-pieterv
    I have some questions about a reaction chain I've come up with.
    I don't know if it is possible or if it is completely correct. The goal of the reaction is to get the oxygen atom out of carbon dioxide.

    1) CO2 + LiAlH4 ----> O=CHO<sup>-</sup>
    2) O=CHO<sup>-</sup> + H2SO4 ----> O-CH-OH
    3) O-CH-OH + CH3<sup>-</sup> ----> <sup>-</sup>O-CHOH-CH3
    4) <sup>-</sup>O-CHOH-CH3 + H2SO4 ----> [CH3-CH-(OH)2] -> O=CH-CH3 + H2O
    5) O=CH-CH3 + LiAlH4 ----> CH3-CH2-O<sup>-</sup>
    6) CH3-CH2-O<sup>-</sup> + H2SO4 ---> HO-CH2-CH3

    Step1: Reduce CO2 with LiAlH4.

    Step2: Add hydrogen atoms to form formic acid

    Step3: Add CH3<sup>-</sup>. Then we get nucleophilic substitution. The CH3<sup>-</sup> cation attacks the carbon atom in O-CH-OH

    Step4: Again add hydrogen atoms. However the resulting product is unstable because of the 2 alcohol function on the same carbon atom. These 2 function 'collapse' and water and an aldehyde are formed

    Step5 and 6: are the same as Step 1 and 2.

    It this possible?

    REPLY: Is this some sort of test ? If so what is it`s purpose ? I do not understand the purpose of your questions. It seems like some sort of exam questions to me. Are you a chemistry teacher ? If so why ask these questions in a forum such as this ? All right you got me going here. QUESTION ONE`S EQUATION IS WRITTEN INCORRECTLY. As to question 3 , CH3 is a free radical and you are going to generate a chain of free radical reactions which are unpredictable unless under controlled conditions. Quetion 2 proposed product does not conform to octet rule and is not possible for that reason. 6 does not balance.product has 1 more hydogen than reactants. 5 does not balance, product has 1 more hydrogen than reactants.6 the reactant is a free radical=unpredictable products quetion 1 does not balance. no hydrogen in reactant. There, did I pass this little test or not. ...Dr.Syntax
    It isn't an exam question. It's just something I've come up with and want to know if these reactions are possible.

    Ok you say that equation 1 is wrong. So I would like to know what's wrong with it.
    CH3<sup>-</sup> is an ION and not a radical. Radicals are written with a dot and not with an - .The - indicates a full negative charge so it's an ION.

    In reaction 2 i have made a typo. The product should be O=CH-OH. And the first reagent in reaction 3 should also be O=CH-OH

    And in question 1 and 5 the extra hydrogen comes from LiAlH4 which losses a hydrogen atom because it's used to create negatively charged hydrogen atoms which attack the other reagent.

    BTW: use a few line feeds. It would be a lot easier to read your response
    REPLY: CH3 is a free radical and an ion, both. Free radicals are often both. The simplest free radical is an electron, An ion and a free radical. The reason the equation is not correctly written is that when you put that+ sign there that designates it as one of the reactants. It is the catalyst. When you write these equations a catalyst is indicated after the reactants with a long arrow with the catalyst written above that arrow. My computer is not set up to write chemistry formulas or I would show you what I mean. Here is a website that gives examples of how to write chemical formulas : [ http://en.wikipedia.org/wiki/Alcohol ]. I don`t have time to address your other quetions at this time. ...DS
    Reply With Quote  
     

  8. #7 Re: Is this possible? 
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    [quote="jan-pieterv"]I have some questions about a reaction chain I've come up with.
    I don't know if it is possible or if it is completely correct. The goal of the reaction is to get the oxygen atom out of carbon dioxide.

    1) CO2 + LiAlH4 ----> O=CHO<sup>-</sup>
    2) O=CHO<sup>-</sup> + H2SO4 ----> O-CH-OH
    3) O-CH-OH + CH3<sup>-</sup> ----> <sup>-</sup>O-CHOH-CH3
    4) <sup>-</sup>O-CHOH-CH3 + H2SO4 ----> [CH3-CH-(OH)2] -> O=CH-CH3 + H2O
    5) O=CH-CH3 + LiAlH4 ----> CH3-CH2-O<sup>-</sup>
    6) CH3-CH2-O<sup>-</sup> + H2SO4 ---> HO-CH2-CH3

    Step1: Reduce CO2 with LiAlH4.

    Step2: Add hydrogen atoms to form formic acid

    Step3: Add CH3<sup>-</sup>. Then we get nucleophilic substitution. The CH3<sup>-</sup> cation attacks the carbon atom in O-CH-OH

    Step4: Again add hydrogen atoms. However the resulting product is unstable because of the 2 alcohol function on the same carbon atom. These 2 function 'collapse' and water and an aldehyde are formed

    Step5 and 6: are the same as Step 1 and 2.

    It this possible?[/quote

    REPLY: Hello Jan, I found this website that I think will be very helpful in explaining the answers to the questios you asked far better than I can: [ http://en.wikipedia.org/wiki/Chemical_bond ]. I think you will find the information you need at this website to answer for yourself, the questions you asked. ...Dr.Syntax
    Reply With Quote  
     

  9. #8  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    From a quick glance, I can see a problem with equation 3.

    Think about what would happen if you mixed formic acid with CH3-...
    Reply With Quote  
     

  10. #9  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by gc
    From a quick glance, I can see a problem with equation 3.

    Think about what would happen if you mixed formic acid with CH3-...

    REPLY: That website: the chemical bond wikipedia ,is worth more than a quick glance. the free radical CH3- ONLY EXISTS MOMENTARILY during chemical reactions. It cannot exist other than momentarily. Jan, did you not read about the octet rule ? It cannot be stored as CH3. What happens when two CH3s come together is that they join to make a C2H6. This is a stable compound known as ethane. By combining the two CH3s the octet rule is fulfilled. Carbon atoms are compelled to make 4 chemical bonds. nitrogens 3 bonds oxygen 2 bonds florine 1 bond. Hydrogens also make 1 bond . So because carbon always wants to make 4 bonds when 2 CH3s meet they are going to combine with each other and make a C2H6, ethane molecule. When those 2 carbons combine the octet rule is fulfilled. In organic chemistry this rule is almost always fulfilled. To know what compounds are possible you have to understand the octet rule. It is a simple rule. Go back to that website and learn what the octet rule means. It is essential if you are going to ever learn even basic chemistry. Goodnight Jan, ...Dr.Syntax
    Reply With Quote  
     

  11. #10  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    Quote Originally Posted by dr.syntax
    REPLY: That website: the chemical bond wikipedia ,is worth more than a quick glance. the free radical CH3- ONLY EXISTS MOMENTARILY during chemical reactions. It cannot exist other than momentarily. Jan, did you not read about the octet rule ? It cannot be stored as CH3. What happens when two CH3s come together is that they join to make a C2H6. This is a stable compound known as ethane. By combining the two CH3s the octet rule is fulfilled. Carbon atoms are compelled to make 4 chemical bonds. nitrogens 3 bonds oxygen 2 bonds florine 1 bond. Hydrogens also make 1 bond . So because carbon always wants to make 4 bonds when 2 CH3s meet they are going to combine with each other and make a C2H6, ethane molecule. When those 2 carbons combine the octet rule is fulfilled. In organic chemistry this rule is almost always fulfilled. To know what compounds are possible you have to understand the octet rule. It is a simple rule. Go back to that website and learn what the octet rule means. It is essential if you are going to ever learn even basic chemistry. Goodnight Jan, ...Dr.Syntax
    CH3- is not a radical, it is an anion with a full octet of 8 electrons. The CH3 radical would be CH3-dot. Of course, it's hard for me to draw these things on here, so perhaps that is the source of confusion.
    Reply With Quote  
     

  12. #11  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    And for the record you can have CH3- (well, sort of - you can have a Grignard reagent like methylmagnesium bromide, which is essentially "CH3-")
    Reply With Quote  
     

  13. #12  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by gc
    Quote Originally Posted by dr.syntax
    REPLY: That website: the chemical bond wikipedia ,is worth more than a quick glance. the free radical CH3- ONLY EXISTS MOMENTARILY during chemical reactions. It cannot exist other than momentarily. Jan, did you not read about the octet rule ? It cannot be stored as CH3. What happens when two CH3s come together is that they join to make a C2H6. This is a stable compound known as ethane. By combining the two CH3s the octet rule is fulfilled. Carbon atoms are compelled to make 4 chemical bonds. nitrogens 3 bonds oxygen 2 bonds florine 1 bond. Hydrogens also make 1 bond . So because carbon always wants to make 4 bonds when 2 CH3s meet they are going to combine with each other and make a C2H6, ethane molecule. When those 2 carbons combine the octet rule is fulfilled. In organic chemistry this rule is almost always fulfilled. To know what compounds are possible you have to understand the octet rule. It is a simple rule. Go back to that website and learn what the octet rule means. It is essential if you are going to ever learn even basic chemistry. Goodnight Jan, ...Dr.Syntax
    CH3- is not a radical, it is an anion with a full octet of 8 electrons. The CH3 radical would be CH3-dot. Of course, it's hard for me to draw these things on here, so perhaps that is the source of confusion.
    REPLY: CH3- is a free radical. That - sign indicates an excess of one electron. An unpaired electron is a free radical. Also if it had another electron which MAY NOT be possible. But if it is possible you would have a VERY REACTIVE ION which would cause ionic reactions to occur. CH3 WITH OR WITHOUT EXCESS ELECTRONS is not a stable entity. I understand what you are saying but it does not matter. Ions are very reactive also. They will set off a chain of ionic reactions. That website is more reliable than me. I don`t know what to say. your starting to ask me questions I am not sure what the answers are. You Take Care, I MEAN THAT, ...Dr.Syntax
    Reply With Quote  
     

  14. #13  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    Quote Originally Posted by dr.syntax
    REPLY: CH3- is a free radical. That - sign indicates an excess of one electron. An unpaired electron is a free radical. Also if it had another electron which MAY NOT be possible. But if it is possible you would have a VERY REACTIVE ION which would cause ionic reactions to occur. CH3 WITH OR WITHOUT EXCESS ELECTRONS is not a stable entity. I understand what you are saying but it does not matter. Ions are very reactive also. They will set off a chain of ionic reactions. That website is more reliable than me. I don`t know what to say. your starting to ask me questions I am not sure what the answers are. You Take Care, I MEAN THAT, ...Dr.Syntax
    No it's not. The negative sign indicates that it has a negative charge. An unpaired electron would be represented by a dot (again, it's hard to draw that on here). The CH3 anion has 3 bonds and one lone pair of electrons. Since each bond is 2 electrons that is 3 x 2 + 2 = 8 electrons.
    As for the formal charge:
    Carbon has 4 valenece electrons, so

    4 - 1/2(6) - 2 = -1

    It has a charge of -1, hence the "-" sign.
    Reply With Quote  
     

  15. #14  
    Forum Freshman
    Join Date
    Feb 2009
    Posts
    23
    I am of the agreement that an isolable CH3(-) species would be rare. However, would you please consider the prospect of a BrMgMe which is the equivalent to a source of "Me-" The reactivity of this "Me-" source would do as you propose, gc is right, reacting a grignard reagent with formic acid would merely protonate the BrMgMe to give CH4. You could however convert formic acid into an ester, then displacement of the OR group by "Me-" would give the carbonyl, which could then be reduced down to the alcohol. This would be a legitimate way of converting formic acid (HOC(O)H) into ethanol (OH-CH2-CH3). The only step that seems tenuous to me is the reduction of of CO2 to HC(O)OH.

    I hope that this helps
    Luka[/url]
    Chemistry is everything!
    Reply With Quote  
     

  16. #15 I would say Luka obviously knows more than I do about this. 
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by gc
    Quote Originally Posted by dr.syntax
    REPLY: CH3- is a free radical. That - sign indicates an excess of one electron. An unpaired electron is a free radical. Also if it had another electron which MAY NOT be possible. But if it is possible you would have a VERY REACTIVE ION which would cause ionic reactions to occur. CH3 WITH OR WITHOUT EXCESS ELECTRONS is not a stable entity. I understand what you are saying but it does not matter. Ions are very reactive also. They will set off a chain of ionic reactions. That website is more reliable than me. I don`t know what to say. your starting to ask me questions I am not sure what the answers are. You Take Care, I MEAN THAT, ...Dr.Syntax
    No it's not. The negative sign indicates that it has a negative charge. An unpaired electron would be represented by a dot (again, it's hard to draw that on here). The CH3 anion has 3 bonds and one lone pair of electrons. Since each bond is 2 electrons that is 3 x 2 + 2 = 8 electrons.
    As for the formal charge:
    Carbon has 4 valenece electrons, so

    4 - 1/2(6) - 2 = -1

    It has a charge of -1, hence the "-" sign.
    REPLY: I will say Luka obviously knows more about this than I do. Just so you are clear about what he is saying Me- is the same as CH3- . Me is shorthand for methyl and that is what CH3 is. I think you found a far more qualified instructor in chemistry than I am in Luka . I enjoyed our little discussions and it was a pleasure to meet you. ...Dr.Syntax
    Reply With Quote  
     

  17. #16 Let me Dr.Syntax ask a question. 
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by Luka
    I am of the agreement that an isolable CH3(-) species would be rare. However, would you please consider the prospect of a BrMgMe which is the equivalent to a source of "Me-" The reactivity of this "Me-" source would do as you propose, gc is right, reacting a grignard reagent with formic acid would merely protonate the BrMgMe to give CH4. You could however convert formic acid into an ester, then displacement of the OR group by "Me-" would give the carbonyl, which could then be reduced down to the alcohol. This would be a legitimate way of converting formic acid (HOC(O)H) into ethanol (OH-CH2-CH3). The only step that seems tenuous to me is the reduction of of CO2 to HC(O)OH.

    I hope that this helps
    Luka[/url]

    REPLY: Hello Luka, my question is this : Is CH3- a free radical or not ? How can it not be. Carbon is element 6 so it has 6 protons . CH3- WOULD INDICATE TO ME , one more electron than protons in this CH3- arrangement and when you do that thing the dots to indicate where the electrons are you still come out with one unpaired electron and therefor a free radical. It is now also an anion. So it is a free radical and an anion. Am I right or wrong about this ? ....Dr.Syntax
    Reply With Quote  
     

  18. #17  
    Forum Freshman
    Join Date
    Feb 2009
    Posts
    23
    Hi,

    Well, I think I can explain this. It does require for you to have some fundemental knowledge of orbital theory, and I am not assuming you do not have it, but you might want to freshen up on the electron filling rules for the first three rows of the periodic table before we go much further.

    Now then, were we to look at C. C is in group 4 as you have correctly assertained, and is in the second row of the periodic table. What this means is that the electrons should be arranged in their orbitals in the following fashion: 1S2, 2S2, 2P2. Hunds rule and the Pauli exclusion principle both apply here as they should anywhere else. However, a covalent bond involves the sharing of of electrons between two nuclei, thus meaning if C only has 2 'free' electrons it would only be able to form 2 bonds. As you are corectly taught from an early stage in your scientific carreer, C forms 4 bonds. This means that there MUST be something else happeneing to the carbon electrons to make them able to form 4 covalent bonds. This process is known as hybridisation. Effectively one alters ones perception of the electronic makeup of the electrons to allow for a scenario in which the following arrangement of electrons is proposed: 1S2 2S1 3P3. It is convetional to think that electrons pair up, however, the fact that they do not is suggestive of the idea that the energy gained from being covalently bound to 4 protons is such that it creates effectively 4 unpaired electrons. Now, in the case of methane (CH4) all of these 4 unpaired electrons become part of a covalent bond. However, were you to form three bonds with hydrogen to give .CH3 you are correct in asserting that you would still have a methyl radical. What you appear to have missed is that the same number of electrons are still present on the C centre, thus not making it anionic. You still have the ability with the free orbital to accept electron density into the one remaining orbital, once this electron is provided you have an anion, and NOT a radical.

    As such then, it becomes apparent that the method of formation of your CH3 species predetermines whether or not it is .CH3 or CH3-. Were you to break the bond homolytically or heterolytically for example. This is beyond the scope of this answer.

    Dependiong on the way that it is formed, CH3 can EITHER be a radical or an anion. It can never be both (to my knowledge).

    Luka
    Chemistry is everything!
    Reply With Quote  
     

  19. #18  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    Quote Originally Posted by Luka
    Dependiong on the way that it is formed, CH3 can EITHER be a radical or an anion. It can never be both (to my knowledge).
    True, CH3 can either be a radical or an anion (or a cation for that matter), but they would be denoted differently:
    CH3(dot) for the radical
    CH3- for the anion
    CH3+ for the cation
    Reply With Quote  
     

  20. #19 Re: Is this possible? 
    Forum Professor
    Join Date
    May 2005
    Posts
    1,893
    Quote Originally Posted by jan-pieterv

    It this possible?
    My organic chem is a little rusty but I can't see anything obviously wrong with it. One problem might be that I'm pretty sure lithium aluminum hydride is able to reduce CO2 all the way to formaldehyde or methanol, so I'm not sure you would get only formic acid from your first step. You might get a mix of different reduction products. You might need a more mild reducing agent.
    Reply With Quote  
     

  21. #20 Re: Let me Dr.Syntax ask a question. 
    Forum Professor
    Join Date
    May 2005
    Posts
    1,893
    Quote Originally Posted by dr.syntax
    REPLY: Hello Luka, my question is this : Is CH3- a free radical or not ? How can it not be. Carbon is element 6 so it has 6 protons . CH3- WOULD INDICATE TO ME , one more electron than protons in this CH3- arrangement and when you do that thing the dots to indicate where the electrons are you still come out with one unpaired electron and therefor a free radical. It is now also an anion. So it is a free radical and an anion. Am I right or wrong about this ? ....Dr.Syntax
    There are also the 3 electrons from the three hydrogens bonded to the central carbon, which causes the CH3- anoin to have 8 valence electrons overall. 4 valence electrons from the carbon, 3 from each of the three bonded hydrogens, and 1 added because it's a 1- anion.
    Reply With Quote  
     

  22. #21  
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    18
    Effectively one alters ones perception of the electronic makeup of the electrons to allow for a scenario in which the following arrangement of electrons is proposed: 1S2 2S1 3P3.
    i think you mean 1S2 2S1 2P3. You put the electrons in the wrong atomic level.

    Are you sure that using LiAlH4 would be the best move. Its far to strong a reducing agent. it would probable reduce both oxygens in the CO2. Also use H2SO4 it would hydrolyse any C=O bonds. I would say use a weaker reducing agent and HCl and water work up.
    Does this cloth smell like chloroform to you?!
    Reply With Quote  
     

  23. #22  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by Gregchf
    Effectively one alters ones perception of the electronic makeup of the electrons to allow for a scenario in which the following arrangement of electrons is proposed: 1S2 2S1 3P3.
    i think you mean 1S2 2S1 2P3. You put the electrons in the wrong atomic level.

    Are you sure that using LiAlH4 would be the best move. Its far to strong a reducing agent. it would probable reduce both oxygens in the CO2. Also use H2SO4 it would hydrolyse any C=O bonds. I would say use a weaker reducing agent and HCl and water work up.


    REPLY: I , Dr.Syntax appreciate that some people with a working knowledge of chemistry are taking part in this discussion, very much. Now I want a simple yes or no to the question is CH3- A FREE RADICAL OR NOT ? Does that - symbol not indicate one more electron than protons ? And if does, does it not make this chemical entity CH3- BOTH A FREE RADICAL AND AN ANION ? ...Dr.Syntax
    Reply With Quote  
     

  24. #23  
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    18
    REPLY: I , Dr.Syntax appreciate that some people with a working knowledge of chemistry are taking part in this discussion, very much. Now I want a simple yes or no to the question is CH3- A FREE RADICAL OR NOT ? Does that - symbol not indicate one more electron than protons ? And if does, does it not make this chemical entity CH3- BOTH A FREE RADICAL AND AN ANION ? ...Dr.Syntax
    No CH3- is not a free radical. CH3- is an anion. Having one more electron than a proton does not make it a radical. A radical is a species that contains an unpaired electron. In CH3- there is no unpaired electron. The "extra" electron on the carbon comes from the hetrolytic fission of a bond on the carbon. The electron config of the carbon atom is 1S2 2S2 2P6.
    Does this cloth smell like chloroform to you?!
    Reply With Quote  
     

  25. #24  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by Gregchf
    REPLY: I , Dr.Syntax appreciate that some people with a working knowledge of chemistry are taking part in this discussion, very much. Now I want a simple yes or no to the question is CH3- A FREE RADICAL OR NOT ? Does that - symbol not indicate one more electron than protons ? And if does, does it not make this chemical entity CH3- BOTH A FREE RADICAL AND AN ANION ? ...Dr.Syntax
    No CH3- is not a free radical. CH3- is an anion. Having one more electron than a proton does not make it a radical. A radical is a species that contains an unpaired electron. In CH3- there is no unpaired electron. The "extra" electron on the carbon comes from the hetrolytic fission of a bond on the carbon. The electron config of the carbon atom is 1S2 2S2 2P6.

    REPLY: The numbers do not equal 7. Explain it in a manner that an idiot like myself can understand. I am not being sarcastic I assure you.Where does that 7th electron exist and what electron IS IT PAIRED WITH ? How can a carbon atom have 7 electrons THAT ARE PAIRED. IT SEEMS IMPOSSIBLE TO ME. The answers presented make no sense to me. I understand the very basic concept of atoms sharing electrons but you guys got me doubting that every thing I ever read regarding the nature of carbon and the principles involved in the sharing of electrons and such,. from what I see here in my basic chemistry books. I still say I am right and that CH3- is both a free radical and an anion. ...Dr.Syntax
    Reply With Quote  
     

  26. #25  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by dr.syntax
    Quote Originally Posted by Gregchf
    REPLY: I , Dr.Syntax appreciate that some people with a working knowledge of chemistry are taking part in this discussion, very much. Now I want a simple yes or no to the question is CH3- A FREE RADICAL OR NOT ? Does that - symbol not indicate one more electron than protons ? And if does, does it not make this chemical entity CH3- BOTH A FREE RADICAL AND AN ANION ? ...Dr.Syntax
    No CH3- is not a free radical. CH3- is an anion. Having one more electron than a proton does not make it a radical. A radical is a species that contains an unpaired electron. In CH3- there is no unpaired electron. The "extra" electron on the carbon comes from the hetrolytic fission of a bond on the carbon. The electron config of the carbon atom is 1S2 2S2 2P6.

    REPLY: The numbers do not equal 7. Explain it in a manner that an idiot like myself can understand. I am not being sarcastic I assure you.Where does that 7th electron exist and what electron IS IT PAIRED WITH ? How can a carbon atom have 7 electrons THAT ARE PAIRED. IT SEEMS IMPOSSIBLE TO ME. The answers presented make no sense to me. I understand the very basic concept of atoms sharing electrons but you guys got me doubting that every thing I ever read regarding the nature of carbon and the principles involved in the sharing of electrons and such,. from what I see here in my basic chemistry books. I still say I am right and that CH3- is both a free radical and an anion. ...Dr.Syntax

    REPLY: I can find nothing on the web that says CH3- EVEN EXISTS EVEN MOMENTARILY. I would think it would, at least momentarily during some chemical reactions. Can anyone out there find a website that discusses CH3- ? ...Dr.Syntax
    Reply With Quote  
     

  27. #26  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    Quote Originally Posted by dr.syntax
    REPLY: I can find nothing on the web that says CH3- EVEN EXISTS EVEN MOMENTARILY. I would think it would, at least momentarily during some chemical reactions. Can anyone out there find a website that discusses CH3- ? ...Dr.Syntax
    You are correct that CH3- doesn't really exist by itself, but for practical purposes there are at least two (off the top of my head) reagents that behave as though they are CH3-. Those reagents are methyl lithium and methylmagnesium bromide (an example of a Grignard reagent
    In these two cases, the metal is much more electropositive, so the bond can essentially be thought of as an ionic bond between CH3- and Li+ (or MgBr+).
    Reply With Quote  
     

  28. #27  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    Quote Originally Posted by dr.syntax
    REPLY: The numbers do not equal 7. Explain it in a manner that an idiot like myself can understand. I am not being sarcastic I assure you.Where does that 7th electron exist and what electron IS IT PAIRED WITH ? How can a carbon atom have 7 electrons THAT ARE PAIRED. IT SEEMS IMPOSSIBLE TO ME. The answers presented make no sense to me. I understand the very basic concept of atoms sharing electrons but you guys got me doubting that every thing I ever read regarding the nature of carbon and the principles involved in the sharing of electrons and such,. from what I see here in my basic chemistry books. I still say I am right and that CH3- is both a free radical and an anion. ...Dr.Syntax
    The CH3' anion has a full octet. I think that the confusion is when calculating the formal charge you only count half of the bonding electrons and compare that to the valency of carbon (which is four). CH3- has 6 bonding electrons (3x2), so half of that would be three. It also has a lone pair, so that is two more for a total of 5. Since 4 - 5 = -1, the charge is -1.
    Reply With Quote  
     

  29. #28  
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    18
    You are correct that CH3- doesn't really exist by itself, but for practical purposes there are at least two (off the top of my head) reagents that behave as though they are CH3-. Those reagents are methyl lithium and methylmagnesium bromide (an example of a Grignard reagent
    In these two cases, the metal is much more electropositive, so the bond can essentially be thought of as an ionic bond between CH3- and Li+ (or MgBr+).
    this works!!

    i'm sorry i didn't get my hybridisation of CH3-. it defiantly isn't 1S2 2S2 2P6. i think its 1S2 2SP3,8.
    Does this cloth smell like chloroform to you?!
    Reply With Quote  
     

  30. #29  
    Forum Freshman
    Join Date
    Feb 2009
    Posts
    23
    This question of the existance of Me- gets me wandering. I suppose that actually very few carbanions are isolablet. We must move on from very simple CH3 systems and look at systems that ARE isolable, inorder to provide evidence for our point.

    The carbon alpha to (one away from) a carbonyl, has the same bond hybridisation to CH4, albeit that instead of covalent bonds to four protons, it now binds to two protons, and two carbon atoms. The protons on this alpha carbon ARE acidic, and the resultant enolate produced on deprotonation is analagous to our CH3- species, except that is is now a C-CH(-)-C anion. This species most definately exists, and is isolable. Because C and H both form covalent bonds to H, they bond in much the same way. Because of this fact the electron count on this KNOWN C- species is the same as that of the hypothetical CH3- species.
    Chemistry is everything!
    Reply With Quote  
     

  31. #30  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by gc
    Quote Originally Posted by dr.syntax
    REPLY: The numbers do not equal 7. Explain it in a manner that an idiot like myself can understand. I am not being sarcastic I assure you.Where does that 7th electron exist and what electron IS IT PAIRED WITH ? How can a carbon atom have 7 electrons THAT ARE PAIRED. IT SEEMS IMPOSSIBLE TO ME. The answers presented make no sense to me. I understand the very basic concept of atoms sharing electrons but you guys got me doubting that every thing I ever read regarding the nature of carbon and the principles involved in the sharing of electrons and such,. from what I see here in my basic chemistry books. I still say I am right and that CH3- is both a free radical and an anion. ...Dr.Syntax
    The CH3' anion has a full octet. I think that the confusion is when calculating the formal charge you only count half of the bonding electrons and compare that to the valency of carbon (which is four). CH3- has 6 bonding electrons (3x2), so half of that would be three. It also has a lone pair, so that is two more for a total of 5. Since 4 - 5 = -1, the charge is -1.

    REPLY: I am still confused. I am sorry but I am. I do that dot thing with the carbon at the center. Then I indicate each of the 3 hydrogens. Each hydrogen contributes it`s one electron and carbon contributes 1 of it`s 4 outer, valence or bonding electrons to this little drawing, representation. So, to give this drawig a formal charge of 1- another electron is added. And in my little drawig it is unpaired. So to me this makes it an anion and a free racical. I am starting to see my error, To be an anion ,I need one more electron than protons it needs a 8th electron added to my little drawing completing the octet.i FINALLY get it. It seems so obvious now. Thank you for taking your valuable time in explaining this to me. And now it is going to grab a proton from some avalable molecule setting in motion a series of ionic reactions. Is this true or not ? I guess I am what you politely call a slow learner. ...Dr,Syntax
    Reply With Quote  
     

  32. #31  
    gc
    gc is offline
    Forum Junior
    Join Date
    Sep 2009
    Posts
    210
    Quote Originally Posted by dr.syntax
    Thank you for taking your valuable time in explaining this to me. And now it is going to grab a proton from some avalable molecule setting in motion a series of ionic reactions. Is this true or not ? I guess I am what you politely call a slow learner. ...Dr,Syntax
    No problem, and yes CH3- is a very strong base, so it will grab pretty much any proton it can (anything with a pka less than about 50).
    Reply With Quote  
     

  33. #32  
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    17
    thanks for the replies everybody and sorry that I reply this late but something is wrong with the e-mail I'm supposed to get

    Quote Originally Posted by Scifor Refugee
    My organic chem is a little rusty but I can't see anything obviously wrong with it. One problem might be that I'm pretty sure lithium aluminum hydride is able to reduce CO2 all the way to formaldehyde or methanol, so I'm not sure you would get only formic acid from your first step. You might get a mix of different reduction products. You might need a more mild reducing agent.
    I'm sure I will get a mix of different reduction product because that mostly the case in organic chemistry. Almost every reaction creates a mix of products.

    I thought to use a very strong reducing agent because it seems to me as if CO2 is very stable and thus hard to reduce. The thing is I wanted something to reduce CO2 with very little energy input. CO2 can be reduced with just H2 is the pressure an temperature is high enough but that's not ideal.

    If these reactions are possible to do with little energy input then you get H2O and an organic product that can be burned. If nuclear fussion plants would then be possible then you can easily capture CO2 do these reactions and release the oxygen from the water using electrolysis. The electricity would come from fussion so there wouldn't be any CO2 produced. The point is that rather simple reactions like these could in the long term provided an outcome to global heating and create fuel from the products produced when that fuel is burned.
    Reply With Quote  
     

  34. #33  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    [quote="jan-pieterv"]thanks for the replies everybody and sorry that I reply this late but something is wrong with the e-mail I'm supposed to get

    Quote Originally Posted by Scifor Refugee
    My organic chem is a little rusty but I can't see anything obviously wrong with it. One problem might be that I'm pretty sure lithium aluminum hydride is able to reduce CO2 all the way to formaldehyde or methanol, so I'm not sure you would get only formic acid from your first step. You might get a mix of different reduction products. You might need a more mild reducing agent.
    I'm sure I will get a mix of different reduction product because that mostly the case in organic chemistry. Almost every reaction creates a mix of products.

    I thought to use a very strong reducing agent because it seems to me as if CO2 is very stable and thus hard to reduce. The thing is I wanted something to reduce CO2 with very little energy input. CO2 can be reduced with just H2 is the pressure an temperature is high enough but that's not ideal.

    If these reactions are possible to do with little energy input then you get H2O and an organic product that can be burned. If nuclear fussion plants would then be possible then you can easily capture CO2 do these reactions and release the oxygen from the water using electrolysis. The electricity would come from fussion so there wouldn't be any CO2 produced. The point is that rather simple reactions like these could in the long term provided an outcome to global heating and create fuel from the products produced when that fuel is burned.[/quote


    REPLY: You have some people taking part in this discussion with a considerable amount of knowledge in chemistry. I do NOT count myself as one of them. I do know that the by products of the complete combustion of any hydrocarbon is CO2 and H20 and heat energy. I don`t think you can turn CO2 into a combustible compound without a large energy input. After all, photo-sythesis is how nature does it so to speak, the sunlight being the energy input. That`s my opinion. If one of the other more knowledgeable people say different I will be surprised. ...Dr.Syntax
    Reply With Quote  
     

  35. #34  
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    17
    The sugar create by photo-synthesis is burned using the citric acid cycle. Here the energy doesn't come from the CO2 that is generated but from the H2O.
    The purpose of the citric acid cycle is to get as much hydrogen out of the sugar. The CO2 is a by product that is produced out of the oxygen an carbon already in the sugar.
    The released hydrogen is then bound to NAD<sup>+</sup> to form NADH.

    The following step the uses this NADH to turn ADP into ATP. This is done by using the Hydrogen to form H2O and energy. The released energy is then used to transform ADP into ATP.

    So basically the energy from burning sugars doesn't come from the CO2 but from the H2O. That's why I think converting CO2 isn't the biggest energy consumer. The big energy input is required to spit H2O using electrolysis. The big advantage is that the electricity used to do it can come from a clean energy source that doesn't produce CO2. Maybe today clean energy source can't produce the enormous amount of electricity that would be used but if nuclear fusion plant start to become economical around 2050 that would be a usable source of energy.
    Reply With Quote  
     

  36. #35 THE ENERGY COMES FROM THE SUN... 
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    Quote Originally Posted by jan-pieterv
    The sugar create by photo-synthesis is burned using the citric acid cycle. Here the energy doesn't come from the CO2 that is generated but from the H2O.
    The purpose of the citric acid cycle is to get as much hydrogen out of the sugar. The CO2 is a by product that is produced out of the oxygen an carbon already in the sugar.
    The released hydrogen is then bound to NAD<sup>+</sup> to form NADH.

    The following step the uses this NADH to turn ADP into ATP. This is done by using the Hydrogen to form H2O and energy. The released energy is then used to transform ADP into ATP.

    So basically the energy from burning sugars doesn't come from the CO2 but from the H2O. That's why I think converting CO2 isn't the biggest energy consumer. The big energy input is required to spit H2O using electrolysis. The big advantage is that the electricity used to do it can come from a clean energy source that doesn't produce CO2. Maybe today clean energy source can't produce the enormous amount of electricity that would be used but if nuclear fusion plant start to become economical around 2050 that would be a usable source of energy.

    REPLY : The energy input is produced by the sun in photo-sytnthesis. What do you not understand about that ? I got confused about ions and free radicals. I am not confused this. Jan, I know that all matter is a condensed form of energy. That does not mean that during chemical reactions you can defy the basic laws of physics. You cannot BURN water. Or in any way generate energy from it by way of chemical reactions. There are laws of physics you cannot defy. ...DS
    Reply With Quote  
     

  37. #36  
    Forum Freshman
    Join Date
    Nov 2009
    Posts
    17
    I was talking about what happens when the sugar is used. I wasn't talking about burning water.
    Reply With Quote  
     

  38. #37  
    Moderator Moderator AlexP's Avatar
    Join Date
    Jul 2006
    Location
    NY
    Posts
    1,838
    dr.syntax, this thread is for chemistry, not your personal life. So keep it out of your posts. Also, if you have things to say that are not in keeping with the topic of this thread, you should start your own thread for them. Thank you.
    "There is a kind of lazy pleasure in useless and out-of-the-way erudition." -Jorge Luis Borges
    Reply With Quote  
     

  39. #38  
    Suspended
    Join Date
    Nov 2009
    Location
    Planet Earth
    Posts
    180
    [quote="Chemboy"]dr.syntax, this thread is for chemistry, not your personal life. So keep it out of your posts. Also, if you have things to say that are not in keeping with the topic of this thread, you should start your own thread for them. Thank you.[/quote



    REPLY: I don`t know what you are talking about. I found what you are talking and will delete it if I can. ...DS
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •