Hypophosphoric acid esters

Hypochlorous acid (s. a. Hypo-halites) 16,231 19,197 Hypohalites (s. a. Alkyl hypo-halites, Potassium hypo-bromite, — hypochlorite, Sodium hypochlorite, — hypoiodite) 17, 352 Hypophosphite s. Sodium dihydrogen hypophosphite Hypophosphoric acid esters... 

Sulfuryl chloride sodium Hypophosphoric acid esters... 

Reduction by hydrogen atom donors involves free radical intermediates and usually proceeds by chain mechanisms. Tri-n-butylstannane is the most prominent example of this type of reducing agent. Other synthetically useful hydrogen atom donors include hypophosphorous acid, dialkyl phosphites, and tris-(trimethylsilyl)silane. The processes that have found most synthetic application are reductive replacement of halogen and various types of thiono esters. 

Reactions with thiono esters, iodides, bromides, and selenides proceed efficiently with dimethyl phosphite or with hypophosphorous acid in the presence of a tertiary amine and AIBN.221... 

The Step 1 product (1427 parts) was converted into the corresponding acrylate ester by treating with acrylic acid (216 parts), sulfuric acid (5 parts) in methyl-cyclohexane (345 parts), hydroquinone monomethyl ether (3 parts), triphenyl phosphite (1 part), and hypophosphorous acid (1 part). The reaction continued until 44 parts of water were removed before beginning the vacuum distillation. The residue was purified by filtering through a K300 filter, and the acid number was determined. The product viscosity was adjusted to 330 mPas by the addition of 96 parts of acrylic acid, and a colorless product was isolated. 

Pudovik, A.N., Moshkina, T.M., and Konovalova, I.V., New method of synthesis of esters of phosphonic and thiophosphonic acids. Part 31. Addition of phosphorous and hypophosphorous acids, dialkyl hydrogen phosphites, and esters of phosphonoacetic acid to esters of maleic acid, Zh. Obshch. Khim., 29, 3338, 1959 Chem. Abstr, 54, 152231, 1960. 

MERCURY(n) NITRATE (10045-94-0, anhydrous 7783-34-8, monohydrate) Hg(N03)2 H,0 Noncombustible solid. Light sensitive. A powerful oxidizer accelerates the burning of combustible materials. Violent reaction, or may form explosive materials, with reducing agents, including hydrides, nitrides, phosphorus, stannous chloride, and sulfides alkyl esters (forms explosive alkyl nitrates) combustible materials (especially if finely divided), phosphinic acid, hypophosphoric acid, metal powders petroleiun hydrocarbons. Forms heat- and/or shock-sensitive compounds with acetylene (forms explosive mercmy acetylide), ethanol and other alcohols (may form explosive mercury fulminates), ferrocene, isobutene, phosphine gas (forms heat- and shock-sensitive precipitate) potassiiun cyanide, sulfur. Incompatible with strong acids, acetic anhydride, ammonia, ammonium hexacyanofenate(II), organic azides, citric acid, hydrazinium perchlorate, isopropyl chlorocarbonate, nitrosyl perchlorate, sodium thiosulfate, sulfamic acid, thiocyanates, hydrozoic acid, methyl isocyanoacetate, sodium peroxyborate, trinitrobenzoic acid, urea nitrate. Aqueous solution corrodes metals. 

Other addition reactions include those of dialkyl hydrogenphosphonates to alkynyl-phosphonic esters under basic catalysis, observed by Saunders and Simpson" and by others (reaction 51) but also of some interest are those additions of hydrogenphosphonates to acetylenic alcohols such as 376 (Scheme 15). The addition of hypophosphorous acid to the alcohols 380 affords the alka-l,2-dienephosphinic acids 381 which, when treated with acid, cyclize to the acids 382 . ... 

In the simplest form of the Abramov reaction, the phosphorus-containing reactant is hypophosphorous acid (phosphinic acid) or an ester thereof, and in the reactions between the acid and formaldehyde or benzaldehyde the initial product is the phosphinic acid 144 (R = H or Ph.). However, the reaction can proceed further to give the bis(l-hydroxyalkyl)phosphinic acid (145 R = H or Ph) the latter (R = Ph) reacts readily with yet more benzaldehyde to give its benzylidene derivative, 5-hydroxy-2,4,6-triphenyl-1,3,5-dioxaphosphorinane 5-oxide (146 R = Ph). When acted on by a second mole of cyclohexanone in the presence of acetyl chloride, (l-hydroxycyclohexyl)phosphinic acid (147) gives the novel phosphinic chloride 148, characterized as the free acid 149 following ready hydrolysis A reaction between a phosphinic acid (150) and a second (non-identical) carbonyl compound leads to an unsymmetrical phosphinic acid (151). Esters of symmetrical 1, r-dihydroxy-substituted phosphinic acids are preparable from hypophosphite esters, H2P(0)0R ". ... 

Many other studies have been concerned with reactions between other 1,4-dike-tones" or 1,5-diketones" and a variety of phosphorus-containing reactants including phosphine", hypophosphorous acid" " and hypophosphorous esters, either alkyl or... 

Diesters of hypophosphorous acid, (RO)2PH (dialkyl hypophosphites or phosphonites), also add to azomethines in particular, the bis(trimethylsilyl) ester is of interest in this respect because of the ease of removal of the ester groups and lack of any need to isolate the intermediates 379 (Scheme 56) This latter procedure also has allowed a synthesis of the phosphinic acids, 380 (n = 0, or... 

In order to activate or enhance the activity of group III of the metabotropic glutamate receptors, new and potent phosphinic agonists were synthesized by Acher et al. in 2007 [54], Indeed, these presynaptic receptors inhibit the adenylate cyclase and the release process. y-Phosphinic acid derivative 49 is the key intermediate for the formation of compounds 51,52 and 53 (Scheme 7). Starting from a radical addition of hypophosphorous acid to the IV-CBz protected vinylglycine methyl ester 48, the phosphinic derivative compound 49 was obtained in 94%... 

Esters of phosphorous acid (phosphonic acid), H3PO3, and hypophosphorous acid (phosphinic acid), H3P02 are dealt with in Chapter 6.7. 

Esters of pyrophosphorous add can be prepared by using sodium dialkyl phosphite and a dialkyl phosphorochloridite (5.321). If a phosphorochloridate ester is used, an ester of hypophosphoric acid is obtained (5.322). 

Diazoalkanes react with hypophosphoric or hypophosphorous acids to give hypophosphate or hypophosphite (phosphinic) esters, respectively. 

Primary phosphinic esters (6.248) are of importance as intermediates because of their reactive P-H bonds. They are obtained when phosphonous dichlorides are reacted with alcohols at ice-cold temperatures (6.249). The low temperature is necessary to prevent cleavage of the second ester group (6.164). They can also be obtained by the hydrolysis of phosphonous diesters (6.224), from phos-phonamidous esters (7.190), or from treatment of hypophosphorous acid with diazoalkanes (6.250). Some ketones will react with hypophosphorous esters to give primary phosphinic esters (6.251). 

Side-group azaphosphane cyclo ligands can be made using formaldehyde and hypophosphorous acid in reaction (7.317). Esters of type (7.318) are known and lanthanide salts of (b) have application as contrast agents in MRl techniques (Chapter 12.13). 

Hydroxypropionic acid ethyl ester) see Ethyl L-lactate 370 Hypophosphorous acid... 

Scheme 5-156). This reaction proceeds with nueleophilic phosphor compounds such as diarylphosphines, anilinium phosphinate, anilinium hypophosphite, hypo-phite esters or hypophosphorous acid. ... 

Hypophosphite Esters. Methyl hypophosphite has been prepared by the reaction between Hypophosphorous Acid and 2,2-dimethoxypropane (eq 11)." However, the product reacts further with the acetone formed to give 1-hydroxy-1,1-dimethylmethylphosphinate (eq 12). 

Hypophosphorous add will add to alkenes (in the presence of a free radical catalyst) (6.209), carbinols (6.210), aldehydes and ketones (6.211) to give phosphinic acids, while diazoalkanes form esters (6.250). 

Dialkoxyphosphines Dialkoxyphosphoranes Hypophosphorous esters Phosphinic acids and esters Phosphonous-----... 

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