Introduction to Organic Chemistry. Fuson, R. The Haloform Reaction. Chemical Reviews. Please enter your institutional email to check if you have access to this content. Please create an account to get access. Forgot Password? Please enter your email address so we may send you a link to reset your password. To request a trial, please fill out the form below.
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If you do not wish to begin your trial now, you can log back into JoVE at any time to begin. Save to playlist. Filter by:. In a ketone, the carbonyl group is bonded to two carbon atoms:.
In both aldehydes and ketones, the geometry around the carbon atom in the carbonyl group is trigonal planar; the carbon atom exhibits sp 2 hybridization. Figure 1. The carbonyl group is polar, and the geometry of the bonds around the central carbon is trigonal planar. The importance of molecular structure in the reactivity of organic compounds is illustrated by the reactions that produce aldehydes and ketones. We can prepare a carbonyl group by oxidation of an alcohol—for organic molecules, oxidation of a carbon atom is said to occur when a carbon-hydrogen bond is replaced by a carbon-oxygen bond.
The reverse reaction—replacing a carbon-oxygen bond by a carbon-hydrogen bond—is a reduction of that carbon atom. Recall that oxygen is generally assigned a —2 oxidation number unless it is elemental or attached to a fluorine. Since carbon does not have a specific rule, its oxidation number is determined algebraically by factoring the atoms it is attached to and the overall charge of the molecule or ion.
In general, a carbon atom attached to an oxygen atom will have a more positive oxidation number and a carbon atom attached to a hydrogen atom will have a more negative oxidation number. This should fit nicely with your understanding of the polarity of C—O and C—H bonds. The other reagents and possible products of these reactions are beyond the scope of this chapter, so we will focus only on the changes to the carbon atoms:.
Methane represents the completely reduced form of an organic molecule that contains one carbon atom. Sequentially replacing each of the carbon-hydrogen bonds with a carbon-oxygen bond would lead to an alcohol, then an aldehyde, then a carboxylic acid discussed later , and, finally, carbon dioxide:. In this example, we can calculate the oxidation number review the chapter on oxidation-reduction reactions if necessary for the carbon atom in each case note how this would become difficult for larger molecules with additional carbon atoms and hydrogen atoms, which is why organic chemists use the definition dealing with replacing C—H bonds with C—O bonds described.
Indicate whether the marked carbon atoms in the three molecules here are oxidized or reduced relative to the marked carbon atom in ethanol:. There is no need to calculate oxidation states in this case; instead, just compare the types of atoms bonded to the marked carbon atoms:. Aldehydes are commonly prepared by the oxidation of alcohols whose —OH functional group is located on the carbon atom at the end of the chain of carbon atoms in the alcohol:. Alcohols that have their —OH groups in the middle of the chain are necessary to synthesize a ketone, which requires the carbonyl group to be bonded to two other carbon atoms:.
An alcohol with its —OH group bonded to a carbon atom that is bonded to no or one other carbon atom will form an aldehyde. An alcohol with its —OH group attached to two other carbon atoms will form a ketone. If three carbons are attached to the carbon bonded to the —OH, the molecule will not have a C—H bond to be replaced, so it will not be susceptible to oxidation.
Formaldehyde, an aldehyde with the formula HCHO, is a colorless gas with a pungent and irritating odor. Formaldehyde causes coagulation of proteins, so it kills bacteria and any other living organism and stops many of the biological processes that cause tissue to decay.
Thus, formaldehyde is used for preserving tissue specimens and embalming bodies. It is also used to sterilize soil or other materials. Formaldehyde is used in the manufacture of Bakelite, a hard plastic having high chemical and electrical resistance. It is made commercially by fermenting corn or molasses, or by oxidation of 2-propanol.
Acetone is a colorless liquid. Among its many uses are as a solvent for lacquer including fingernail polish , cellulose acetate, cellulose nitrate, acetylene, plastics, and varnishes; as a paint and varnish remover; and as a solvent in the manufacture of pharmaceuticals and chemicals. What is the structure of the functional group and the condensed formula for 4,4,5-triethyl What reactants combine to form 3-chlorooctane?
How can I draw the following amines: butanamine, pentanamine, propan-1,2-diamine? What is N- 2,2,2-Trichloroethyl carbonyl] Bisnor- cis -tilidine's functional group? What should I start learning after learning the basics of alkanes, alkenes, and alkynes? Write structural formula condensed for all the primary , secondary and tertiary haloalkanes An alcohol has the molecular formula C4H10O write the structural formulae of the isomers to show
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