Alkyl tertiary

By using a lOOX excess of the metal (less than lOO for experiments on a large scale) one can save much time. Some Grignard reactions, especially those with tertiary alkyl chlorides and cyclohexyl chloride, are not easily started and it seemed desirable, therefore, to inform the user of this book about our experiences. 

Secondary alkyl group Tertiary alkyl group... 

Those derived from isobutane are the 2 methylpropyl (isobutyl) group and the 1 1 dimethylethyl (tert butyl) group Isobutyl is a primary alkyl group because its poten tial point of attachment is to a primary carbon tert Butyl is a tertiary alkyl group because Its potential point of attachment is to a tertiary carbon... 

Give the structures and lUPAC names of all the C5H11 alkyl groups and identify them as primary secondary or tertiary alkyl groups as appropriate... 

Alcohols and alkyl halides are classified as primary secondary or tertiary according to the degree of substitution of the carbon that bears the functional group (Section 2 13) Thus primary alcohols and primary alkyl halides are compounds of the type RCH2G (where G is the functional group) secondary alcohols and secondary alkyl halides are compounds of the type R2CHG and tertiary alcohols and tertiary alkyl halides are com pounds of the type R3CG... 

FIGURE 4 13 The order of carbocation stability is methyl < primary < second ary < tertiary Alkyl groups that are directly attached to the positively charged car bon stabilize carbocations... 

Bromination is normally used only to prepare tertiary alkyl bromides from alkanes... 

Tertiary alkyl halide fastest rate of El elimination... 

Having just learned that tertiary alkyl halides are practically inert to substitution by the Sn2 mechanism because of steric hindrance we might wonder whether they undergo nucleophilic substitution at all We 11 see m this section that they do but by a mecha nism different from 8 2... 

Tertiary alkyl halides are so sterically hindered to nucleophilic attack that the pres ence of any anionic Lewis base favors elimination Usually substitution predominates over elimination m tertiary alkyl halides only when anionic Lewis bases are absent In the solvolysis of the tertiary bromide 2 bromo 2 methylbutane for example the ratio of substitution to elimination is 64 36 m pure ethanol but falls to 1 99 m the presence of 2 M sodium ethoxide... 

The few studies that have been carried out with optically active tertiary alcohols indicate that almost complete racemization accompanies the preparation of tertiary alkyl halides by this method... 

Unbranched primary alcohols and tertiary alcohols tend to react with hydrogen halides without rearrangement The alkyloxonmm ions from primary alcohols react rap idly with bromide ion for example m an Sn2 process Tertiary alcohols give tertiary alkyl halides because tertiary carbocations are stable and show little tendency to rearrange... 

Section 8 13 When nucleophilic substitution is used for synthesis the competition between substitution and elimination must be favorable However the normal reaction of a secondary alkyl halide with a base as strong or stronger than hydroxide is elimination (E2) Substitution by the Sn2 mechanism predominates only when the base is weaker than hydroxide or the alkyl halide is primary Elimination predominates when tertiary alkyl halides react with any anion... 

Rate IS governed by stability of car bocation that is formed in loniza tion step Tertiary alkyl halides can react only by the SnI mechanism they never react by the Sn2 mecha nism (Section 8 9) Rate IS governed by steric effects (crowding in transition state) Methyl and primary alkyl halides can react only by the Sn2 mecha nism they never react by the SnI mechanism (Section 8 6)... 

The acidity of acetylene and terminal alkynes permits them to be converted to their conjugate bases on treatment with sodium amide These anions are good nucleophiles and react with methyl and primary alkyl halides to form carbon-carbon bonds Secondary and tertiary alkyl halides cannot be used because they yield only elimination products under these conditions... 

A substantial body of evidence indicates that allylic carbocations are more stable than simple alkyl cations For example the rate of solvolysis of a chlonde that is both tertiary and allylic is much faster than that of a typical tertiary alkyl chloride... 

The alkyl halide can be primary secondary or tertiary Alkyl iodides are the most reac tive followed by bromides then chlorides Fluorides are relatively unreactive... 

R may be methyl or primary secondary or tertiary alkyl it may also be a cycloalkyl alkenyl or aryl group)... 

Methyl and primary alkyl halides especially iodides work best Elimination becomes a problem with secondary and tertiary alkyl halides... 

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... 

Tertiary alkyl > secondary alkyl > primary alkyl > methyl... 

The reaction is of the 8 2 type and works best with primary and secondary alkyl halides Elimination is the only reaction observed with tertiary alkyl halides Aryl and vinyl halides do not react Dimethyl sulfoxide is the preferred solvent for this reaction but alcohols and water-alcohol mixtures have also been used... 

Because fhe new carbon-carbon bond is formed by an 8 2 lype reaction fhe alkyl halide musl nol be slerically hindered Melhyl and primary alkyl halides work besl secondary alkyl halides give lower yields Tertiary alkyl halides fail reacting only by elimination nol subslilulion... 

The alkyl halide must be one that reacts readily by an 8 2 mechanism Thus methyl and primary alkyl halides are the most effective alkylating agents Elimination competes with substitution when secondary alkyl halides are used and is the only reac tion observed with tertiary alkyl halides... 

Tertiary alkyl group (Section 2 13) Structural unit of the type R3C— in which the point of attachment is to a tertiary carbon... 

Because of isomerization, alkylation of benzene with tertiary alkyl haUdes can also yield secondary alkylbenzenes rather than only tertiary alkylbenzenes (20). For example, the / fAhexylbenzene, which is first formed by the reaction of benzene with 2-chloro-2,3-dimethylbutane and AlCl isomerizes largely to 2,2-dimethyl-3-phenylbutane by a 1,2-CH2 shift. With ferric chloride as the catalyst, / fAhexylbenzene does not undergo isomerization and is isolated as such. 

Tertiary alkyl chlorides have been converted to the tertiary nittiles with trimethylsilyl nittile ia dichioromethane ia the presence of SnCl (131). The reaction was appHed to the synthesis of several bridgehead nittiles, such as 1-adamantyl and 1-diamantyl nittiles from the corresponding chloro or bromo derivatives usiag SnCl or AIBr. catalysts (132). 

Dialkyl peroxides have the stmctural formula R—OO—R/ where R and R are the same or different primary, secondary, or tertiary alkyl, cycloalkyl, and aralkyl hydrocarbon or hetero-substituted hydrocarbon radicals. Organomineral peroxides have the formulas R Q(OOR) and R QOOQR, where at least one of the peroxygens is bonded directly to the organo-substituted metal or metalloid, Q. Dialkyl peroxides include cyclic and bicycflc peroxides where the R and R groups are linked, eg, endoperoxides and derivatives of 1,2-dioxane. Also included are polymeric peroxides, which usually are called poly(alkylene peroxides) or alkylene—oxygen copolymers, and poly(organomineral peroxides) (44), where Q = As or Sb. 

Tertiary Alkyl Hydroperoxides, Product Bulletin, Atochem North America, Inc., Buffalo, N.Y., Nov. 1991. 

Ritter Reaction (Method 4). A small but important class of amines are manufactured by the Ritter reaction. These are the amines in which the nitrogen atom is adjacent to a tertiary alkyl group. In the Ritter reaction a substituted olefin such as isobutylene reacts with hydrogen cyanide under acidic conditions (12). The resulting formamide is then hydroly2ed to the parent primary amine. Typically sulfuric acid is used in this transformation of an olefin to an amine. Stoichiometric quantities of sulfate salts are produced along with the desired amine. 

For extraction of uranium from sulfate leach Hquors, alkyl phosphoric acids, alkyl phosphates, and secondary and tertiary alkyl amines are used in an inert diluent such as kerosene. The formation of a third phase is suppressed by addition of modifiers such as long-chain alcohols or neutral phosphate esters. Such compounds also increase the solubihty of the amine salt in the diluent and improve phase separation. 

For solvent extraction of pentavalent vanadium as a decavanadate anion, the leach solution is acidified to ca pH 3 by addition of sulfuric acid. Vanadium is extracted in about four countercurrent mixer—settler stages by a 3—5 wt % solution of a tertiary alkyl amine in kerosene. The organic solvent is stripped by a soda-ash or ammonium hydroxide solution, and addition of ammoniacal salts to the rich vanadium strip Hquor yields ammonium metavanadate. A small part of the metavanadate is marketed in that form and some is decomposed at a carefully controlled low temperature to make air-dried or fine granular pentoxide, but most is converted to fused pentoxide by thermal decomposition at ca 450°C, melting at 900°C, then chilling and flaking. 

Various vinyl chloride adducts can be formed under acid-catalyzed Friedel-Crafts conditions. Vinyl chloride can add tertiary alkyl haHdes (54). It can... 

The triaLkoxy(aryloxy)boranes are typically monomeric, soluble in most organic solvents, and dissolve in water with hydrolysis to form boric acid and the corresponding alcohol and phenol. Although the rate of hydrolysis is usually very fast, it is dependent on the bulk of the alkyl or aryl substituent groups bonded to the boron atom. Secondary and tertiary alkyl esters are generally more stable than the primary alkyl esters. The boron atom in these compounds is in a trigonal coplanar state with bond hybridization. A vacantp orbital exists along the threefold axis perpendicular to the BO plane. 

Ghlorohydrination with er -All l Hypohalites. Olefins react with ethyl hypochlorite [624-85-1] to form the corresponding chlorohydrin (49). In 1938 both Shell Development Co. (50) and Arthur D. Litde, Inc. (51) patented the preparation of chlorohydrins by the reactions of olefins with tertiary alkyl hypochlorites. Examples with ethylene and propylene in the Shell patent reported chlorohydrin yields of greater than 95% with tert-huty hypochlorite [507-40-4]. 

Almost 40 years later the Lummus Co. patented an integrated process involving the addition of chlorine along with the sodium chloride and sodium hydroxide from the cathode side of an electrolytic cell to a tertiary alcohol such as tertiary butanol to produce the tertiary alkyl hypochlorite. The hypochlorite phase separates, and the aqueous brine solution is returned to the electrolytic cells. The alkyl hypochlorite reacts with an olefin in the presence of water to produce a chlorohydrin and the tertiary alcohol, which is returned to the chlorinator. With propylene, a selectivity to the chlorohydrin of better than 96% is reported (52). A series of other patents covering this technology appeared during the 1980s (53—56). 

Alkyl tertiary alkyl ethers can be prepared by the addition of an alcohol or phenol to a tertiary olefin under acid catalysis (Reycler reaction) sulfuric acid, phosphoric acid, hydrochloric acid, and boron trifluoride have all been used as catalysts ... 

Commercially, sulfonic acid ion-exchange resins are used in fixed-bed reactors to make these tertiary alkyl ethers (14). Since the reaction is very selective to tertiary olefins and also reversible, a two-step procedure is also used to recover commercially pure tertiary olefins from mixed olefin process streams. The corresponding tertiary alkyl ether is produced in the olefin mixture and then easily separated from the unreacted olefins by simple fractionation. The reaction is then reversed in a second step to make a commercially pure tertiary olefin, usually isobutylene or isoamylene. 

Isobutyl bromide (l-bromo-2-methylpropane) [78-77-3] M 137.0, b 91.2 , d 1.260, n 1.437. Partially hydrolysed to remove any tertiary alkyl halide, then fractionally distd, washed with cone H2SO4, water and aqueous K2CO3, then redistd from dry K2CO3. [Dunbar and Hammett J Am Chem Soc 72 109 7950.1... 

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