Mari

R. H. Ottewill, thesis. University of London, Queen Mary College, 1951 see also Ref. 36. 

Give the lUPAC name for each of the following alkyl groups and classify each one as pn mary secondary or tertiary... 

A mechanism for the formation of these three alkenes is shown m Figure 5 9 Dissociation of the primary alkyloxonmm ion is accompanied by a shift of hydride from C 2 to C 1 This avoids the formation of a primary carbocation leading instead to a sec ondary carbocation m which the positive charge is at C 2 Deprotonation of this carbo cation yields the observed products (Some 1 butene may also arise directly from the pri mary alkyloxonium ion)... 

The 8n2 mechanism is believed to describe most substitutions m which simple pri mary and secondary alkyl halides react with anionic nucleophiles All the examples cited in Table 8 1 proceed by the 8 2 mechanism (or a mechanism very much like 8 2— remember mechanisms can never be established with certainty but represent only our best present explanations of experimental observations) We 11 examine the 8 2 mecha nism particularly the structure of the transition state in more detail in 8ection 8 5 after hrst looking at some stereochemical studies carried out by Hughes and Ingold... 

If however the base itself is a crowded one such as potassium tert butoxide even pn mary alkyl halides undergo elimination rather than substitution... 

A second factor that can tip the balance m favor of substitution is weak basicity of the nucleophile Nucleophiles that are less basic than hydroxide react with both pri mary and secondary alkyl halides to give the product of nucleophilic substitution m high yield To illustrate cyanide ion is much less basic than hydroxide and reacts with 2 chlorooctane to give the corresponding alkyl cyanide as the major product... 

The degree to which allylic radicals are stabilized by delocalization of the unpaired electron causes reactions that generate them to proceed more readily than those that give simple alkyl radicals Compare for example the bond dissociation energies of the pri mary C—H bonds of propane and propene... 

The type of alcohol produced depends on the carbonyl compound Substituents present on the carbonyl group of an aldehyde or ketone stay there—they become sub stituents on the carbon that bears the hydroxyl group m the product Thus as shown m Table 14 3 (following page) formaldehyde reacts with Grignard reagents to yield pri mary alcohols aldehydes yield secondary alcohols and ketones yield tertiary alcohols... 

The most frequently used organocuprates are those m which the alkyl group is pri mary Steric hindrance makes secondary and tertiary dialkylcuprates less reactive and they tend to decompose before they react with the alkyl halide The reaction of cuprate reagents with alkyl halides follows the usual 8 2 order CH3 > primary > secondary > tertiary and I > Br > Cl > F p Toluenesulfonates are somewhat more reactive than halides Because the alkyl halide and dialkylcuprate reagent should both be primary m order to produce satisfactory yields of coupled products the reaction is limited to the formation of RCH2—CH2R and RCH2—CH3 bonds m alkanes... 

Carboxylic acids are exceedingly difficult to reduce Acetic acid for example is often used as a solvent in catalytic hydrogenations because it is inert under the reaction con ditions A very powerful reducing agent is required to convert a carboxylic acid to a pri mary alcohol Lithium aluminum hydride is that reducing agent... 

Potassium permanganate (KMn04) will also oxidize pri mary alcohols to carboxylic acids What is the oxidation state of manganese in KMn04 ... 

Secondary and tertiary alkyl halides are not suitable because they react with alkox ide bases by E2 elimination rather than by 8 2 substitution Whether the alkoxide base IS primary secondary or tertiary is much less important than the nature of the alkyl halide Thus benzyl isopropyl ether is prepared m high yield from benzyl chloride a pri mary chloride that is incapable of undergoing elimination and sodium isopropoxide... 

The same reduction methods may be applied to the conversion of nitriles to pn mary amines... 

Alkylation (Section 22 12) Amines act as nucleophiles toward alkyl halides Pri mary amines yield secondary amines secondary amines yield tertiary amines and tertiary amines yield quaternary ammonium salts... 

The task of relating carbohydrate configurations to names requires either a world class memory or an easily recalled mnemonic A mnemonic that serves us well here was pop ularized by the husband-wife team of Lours F Fieser and Mary Fieser of Harvard Uni versity m their 1956 textbook Organic Chemistry As with many mnemonics it s not clear who actually invented it and references to this particular one appeared m the chem ical education literature before publication of the Fiesers text The mnemonic has two features (1) a system for setting down all the stereoisomeric d aldohexoses m a logical order and (2) a way to assign the correct name to each one... 

What was not anticipated was that m 1998 Celera Genomics of Rockville Mary land would undertake its own privately funded program toward the same goal By 2000 the two groups agreed to some coordination of their efforts and published draft sequences in 2001 with final versions expected m 2003... 

Diazotization (Section 22 16) The reaction by which a pn mary arylamine is converted to the corresponding diazo mum ion by nitrosation... 

Jean Marie Farina Jeffamines Jeffrey s rule Jellies... 

Mary R. Seim and co-workers. Chemicals and Processing Assessment of Candidate Explosivesfor the Advanced Bomb Family, IHTR 1370, NOS, Indian Head, Md., June 1990. 

Jean Marie Earina (Roger GaUet 1806) De LanccJ)me (LanccJ)me 1975)... 

In 1896, only a few months after Roentgen aimounced the observation of x-rays, Becquerel reported the additional observation of penetrating radiation emitted from certain natural materials, a phenomenon that Marie Curie would later name radioactivity. This phenomenon had a much less glamorous development. Over a three-year period, Becquerel pubHshed three articles, decided there was Htfle else to learn about it, and went on to the study... 

David L. Clark D. Ww Keogh Mary P. Neu Wolfgang Runde... 

Conferences on Carbon, American Carbon Society, St. Marys, Pa. (held every two years siace 1953). 

Lile H. Deinard Nicholas J. Stathis Mary E. Rasenberger White Case... 

---