Sodium hypochlorite in acetic acid.

General Procedure for Selective Oxidation of Secondary Alcohols in Presence of Primary Alcohol, Using Stevens Protocol (Sodium Hypochlorite in Acetic Acid)... 

To make the DERA-catalyzed process commercially attractive, improvements were required in catalyst load, reaction time, and volumetric productivity. We undertook an enzyme discovery program, using a combination of activity- and sequence-based screening, and discovered 15 DERAs that are active in the previously mentioned process. Several of these enzymes had improved catalyst load relative to the benchmark DERA from E. coli. In the first step of our process, our new DERA enzymes catalyze the enantioselective tandem aldol reaction of two equivalents of acetaldehyde with one equivalent of chloroacetaldehyde (Scheme 20.6). Thus, in 1 step a 6-carbon lactol with two stereogenic centers is formed from achiral 2-carbon starting materials. In the second step, the lactol is oxidized to the corresponding lactone 7 with sodium hypochlorite in acetic acid, which is crystallized to an exceptionally high level of purity (99.9% ee, 99.8% de). 

The treatment of isatin with sodium hypochlorite in acetic acid leads to 1-chloroisatin, an effective mild oxidizing agent for the conversion of alcohols to aldehydes and ketones110 and of indoles to 3-chloroindoles without formation of by-products111. N-[phenyliodine(III)] bisisatin can be obtained from the sodium salt of isatin and phenyliodine (IE) bistrifluoroacetate in 85% yield. This compound is a member of a group of iodine(III)imides,... 

Hypochlorites are very good oxidizers of alcohols and are frequently selective enough to oxidize secondary alcohols in preference to primary alcohols see equations 288-291). Solutions of sodium hypochlorite in acetic acid react exothermically with secondary alcohols within minutes [693]. Calcium hypochlorite in the presence of an ion exchanger (IRA 900) oxidizes secondary alcohols at room temperature in yields of 60-98% [76 5]. Tetrabutylammonium hypochlorite, prepared in situ from 10% aqueous sodium hypochlorite and a 5% dichloromethane solution of tetrabutylammonium bisulfate, oxidizes 9-fluorenol to fluorenone in 92% yield and benzhydrol to benzophenone in 82% yield at room temperature in 35 and 150 min, respectively [692]. Cyclohexanol is oxidized to cyclohexanone by teit-butyl hypochlorite in carbon tetrachloride in the presence of pyridine. The exothermic reaction must be carried out with due precautions [709]. 

Oxidation of alcohols is often aeeomplished conveniently by or via hypochlorites in sueh Ireatment of primary-seeondary diols, a selectivity of 1 7-20 is reached for the seeondary hydroxyl group. In general, sodium hypochlorite in acetic acid solution is used for this purpose (25). We obtained very good results, based on chlorine or trichloroisocyanuric acid (TCIA) in methanol in acid-buffered medium. The hy-droxyketone [7] can be formed reliably with a selectivity of 1 50-65. The improved selectivity is based on the use of the lowest convenient temperature and on the Promotion of the exchange of positive chlorine between primary and secondary alcohol positions (including from relatively stable methyl hypochlorite). 

Sodium hypochlorite in acetic acid is an oxidizing agent capable of oxidizing alcohols to the corresponding aldehydes or ketones. In this experiment, you will oxidize a diol, 2-ethyl-l,3-hexanediol (1) and then use infrared spectroscopy to determine which of the alcohol functional groups was oxidized. 

Oxidative Methods.—A convenient and inexpensive procedure for the oxidation of secondary alcohols to ketones, applicable to multi-mole preparations, uses aqueous sodium hypochlorite in acetic acid/ Selective oxidation of secondary alcohols is possible as primary alcohols are oxidized much more slowly. Alcohol oxidations with molecular bromine in combination with nickel(ll) benzoate in acetonitrile are remarkably free from competing reactions. However, 1,4-diols yield butyrolactones. ... 

At even higher pH values, metal catalysis is required for chlorination to proceed. Thus, at pH =11, nickel(salen) catalyzes the chlorination of adamantane, cyclohexane and toluene785 and manganese porphyrin promotes the chlorination of cyclohexane786. Selective side-chain chlorination by sodium hypochlorite under PTCs at pH = 8.5 has been used for benzylic chlorinations787,788 and for the functionalization of poly(4-methyl-styrene)789,790. Similarly, with calcium hypochlorite in acetic acid, ring chlorination is reported for toluene, xylenes, anisole and other activated aromatics791. 

Aliphatic nitroso compounds can be prepared from IV-alkylhydioxylamines oxidation widi bromine, chlorine or sodium hypochlorite in weakly acidic solution, reaction with potassium dichromate in acetic or sulfuric acid, and by oxidation widi yellow mercury(II) oxide in suspension in an organic solvent. Silver carbonate on Celite has also been used to prepare aliphatic nitroso compounds, such as ni-trosocyclohexane, in high yield from the corresponding hydroxylamines." Aqueous sodium periodate and tetraalkylanunonium periodates, which are soluble in organic solvents, are the reagents most commonly used for the oxidation of hydroxamic acids and IV-acylhydroxylamines to acylnitroso compounds... 

Oxidation of CHOH (7, 337). Sodium hypochlorite solutions1 oxidize secondary alcohols dissolved in acetic acid to ketones in yields of 90-95%. Selective oxidation in the presence of a primary alcohol group is possible. The oxidation has been conducted, with suitable precautions, on a large scale.2... 

Chloroindole has been prepared from indole and sulfuryl chloride (66JOC2627) and 3-bromo- and 3-iodo-indole have been obtained by direct halogenation in DMF (82S1096). 2-Methylindole reacts with sodium hypochlorite in carbon tetrachloride to give a 2 1 mixture of 1,3- and 3,3- dichloro derivatives (81JOC2054). 3-Substituted indoles are halogenated to yield 3-haloindolenium ions which react in a variety of ways, as illustrated by the reaction of 3-methylindole with NBS in aqueous acetic acid (Scheme 12). 

In 1980, Stevens et al.10 reported that a plain solution of sodium hypochlorite, which is easily available as swimming pool chlorine , is able to efficiently oxidize secondary alcohols in a solution in acetic acid, while primary alcohols react very slowly. Two years later, this research team published11 a more detailed account on the ability of NaOCl/AcOH to perform the selective oxidation of secondary alcohols in the presence of primary ones. Stevens oxidant became one of the standard reagents for the selective oxidation of secondary alcohols.12... 

Approximately 1.05 3a equivalents of sodium hypochlorite (MW = 74.44) in an aqueous ca. 1.8 M b solution are slowly added over 15-30 min.c to a ca. 0.6 1.4 M stirred solution of the diol in acetic acid. When most of the starting alcohol is consumed,d a saturated NaHCCF aqueous solution is added and the resulting mixture is extracted with an organic solvent such as ether or CH2C12. The organic phase is washed with water, dried (MgS04) and concentrated, providing a hydroxyketone that may need further purification. 

In place of elementary chlorine (bromine), sodium hypochlorite in the presence of mineral acid is used in certain cases (e.g., chlorination of acet-o-toluidide). The nascent chlorine reacts very energetically and undesirable side reactions do not occur. 

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