Alkanes From carbonyl groups

The copolymerization of ethene and CO produces an interesting polar material with alternating C2 alkane and carbonyl groups. If a monosub-stituted alkene is used, isotactic and syndiotactic polymers can result. The usual catalyst for such a process is a Pd-phosphine complex. If the phosphine ligand is chiral, stereoregularity with reference to the pendant group from the alkene can result. 

IUPAC Names Systematic names of ketones are derived by replacing the final -e in the alkane name with -one. The alkane name becomes alkanone. In open-chain ketones, we number the longest chain that includes the carbonyl carbon from the end closest to the carbonyl group, and we indicate the position of the carbonyl group by a number. In cyclic ketones, the carbonyl carbon atom is assigned the number 1. 

A carbonyl group dramatically increases the acidity of the protons on the a carbon atom because deprotonation gives a resonance-stabilized enolate ion. Most of the enolate ion s negative charge resides on the electronegative oxygen atom. The pKa for removal of an a proton from a typical ketone or aldehyde is about 20, showing that a typical ketone or aldehyde is much more acidic than an alkane or an alkene (pKa > 40), or even an alkyne (pKa = 25). Still, a ketone or aldehyde is less acidic than water (pKa = 15.7) or an alcohol (pA a = 16 to 18). When a simple ketone or aldehyde is treated with hydroxide ion or an alkoxide ion, the equilibrium mixture contains only a small fraction of the deprotonated, enolate form. 

The systematic name for an aldehyde is obtained from the parent alkane by removing the final -e and adding -al. For ketones the final -e is replaced by -one, and a number indicates the position of the carbonyl group where necessary. Examples of common aldehydes and ketones are shown in Fig. 22.13. Note that since the aldehyde functional group always occurs at the end of the carbon chain, the aldehyde carbon is assigned the number 1 when substituent positions are listed in the name. 

Alkyl phenyl telluriums, obtained from alkyl halides and arenetellurolates, are reduced by triphenyl tin hydride to alkanes under mild conditions The alkanes were obtained in yields ranging from 71 to 95%. 5a-Cholestan-3a-yl phenyl tellurium was similarly reduced to 5a-cholestane in 89% yield. The reaction appears to be highly chemoselective as indicated by the reduction of an epoxide to an alcohol in the presence of a carbonyl group. ... 

Fig. 1.1. Shapes of molecules represented by envelopes of constant electronic charge density. The envelope shown has the value of 0.001 au. The molecules are (a)-(f) the normal alkanes from methane to hexane (g) isobutane (h) neopentane (i) cyclopropane (j) cyclobutane (k) formaldehyde, H2OK) (/) acetone, (CH3)2C=0. The intersections of the zero-flux interatomic surfaces with the envelope are shown in some cases. They define the methyl, methylene, hydrogen, and carbonyl groups. The isobutane molecule (g), for example, exhibits three methyl groups topped...

The C atom on the carbonyl group is included in the count of C atoms when determining the alkane from which the aldehyde is derived. ... 

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