Mask, ammonia

Alkaloids vary widely in structure, from the simple to the enormously complex. The odor of rotting fish, for example, is caused largely by methylamine, CH3NH2, a simple relative of ammonia in which one of the NH3 hydrogens has been replaced by an organic CH3 group. In fact, the use of lemon juice to mask fish odors is simply an acid-base reaction of the citric acid in lemons with methylamine base in the fish. 

In contrast, A, JV-diethyl-3-(methylsulfanyl)-5-phenyl-3//-azepin-2-amine (22) on treatment with methyl or benzyl halides and potassium amide in liquid ammonia undergoes alkylation solely at the masked benzylic 5-position to yield 4,4-disubstituted 4//-azepines, e.g. 23.224... 

A-Acido imines (R R"C = N —X=0) like /V-acyl (X = CR) /V-sulfonyl [X = S(R)=0]2-7 or /V-diphenylphosphinoylimines [X = P(C6H5)2]3 are masked inline derivatives of ammonia. Compared to the imines themselves these activated derivatives are better electrophiles showing less tendency to undergo undesired deprotonation rather than addition of organometal-lics1812 The apparent advantages of these compounds have been exploited for asymmetric syntheses of amines, amides, amino acids and /J-lactams1-8 I6. 

TV-aluminum imines are another example of masked inline derivatives of ammonia. They are easily synthesized by partial reduction of nitriles with diisobutylaluminum hydride (D1BAL-H)6. Addition of lithium organic reagents to /V-aluminum iniines 7 derived from O-protected cyanohydrins 6 provides a-amino alcohols 8a and 8b in moderate yields and low to good diastereo-selectivities n 12. 

Addition of organometallics to hydrazones provides hydrazines1, which can be converted to the corresponding amines by hydrogenolysis. Hydrazones can therefore be regarded as masked imine derivatives of ammonia. This methodology has been utilized successfully for numerous stereoselective syntheses of amines and amine derivatives2-23. 

Possible danger to respiratory tract from fumes ammonia, acetone, nail polish remover, heated sulfur, moth balls Make sure there is good ventilation. Never smell fumes directly. Wear a mask. Leave foul area and notify your teacher immediately. 

Liquid household bleach is generally a 5% solution of sodium hypochlorite (NaOCl). Ammonia cleansers—including general household cleansers, wax removers, glass and window cleaners, and oven cleaners — are aqueous solutions of 5-10% ammonia, NH3. Mixing bleach with cleansers containing ammonia leads to the formation of a family of potentially toxic compounds known as chloramines. These toxic gases have acrid fumes that can bum mucous membranes. Scented bleaches can mask one s natural ability to detect these harmful fumes. 

Full face mask with chemical canister MSA Industrial Canister, Gas Mask3 02 > 19.5% type N canister for concentrations less than 100 times PEL and less than the IDLH concentration for acid gases, CO, ammonia, and organic vapors escape concentrations of 2% for acid gases, CO, and organic vapors and 3% for ammonia escape capacity less than 6 min... 

Dissolve the sample in nitric acid. Separate Pb by extraction with CHC solution of sodium diethyl dithiocarbonate using alkaline cyanide solution to mask interferences. Titrate Pb in an ammonia-ammonium chloride medium at pH =10 using eriochrome black T. 

Potassium Hydroxide (caustic potash) will work on certain chemicals and biological agents. Remarks under sodium hydroxide apply across the board to potassium hydroxide. Ammonia or Ammonium Hydroxide (household ammonia) can be used to decontaminate G nerve agents but takes longer than sodium hydroxide or potassium hydroxide. SCBA or a special purpose mask is required when working with this product. Ammonium hydroxide needs no further mixing it is a water solution of ammonia. 

Are there two suitable full face masks with ammonia canisters as approved by the Bureau of Mines Is self-contained breathing air apparatus required in concentrated atmospheres ... 

Use a grease pencil or masking tape to label each of five small plastic cups. Use A for distilled water, B for ethanol, C for isopropyl alcohol, D for acetone, and E for household ammonia. 

The masking of the normal reaetions of simple ligands, such as the nitro, cyano, and ammonia groups, by coordination to a metal is a phenomenon encountered early by a chemist. One of the first examples of masking in a chelate complex was reported, signifieantly, in biological journals. It involves the protection by copper ion of the a-amino group in ornithine and lysine ... 

Figure 22. Human embryonic kidney cells (A), rat vascular smooth muscle cells (B, C) and human osteoblast-like MG 63 cells (D) in cultures on micropattemed surfaces. A, B PTFE irradiated with UV light produced by a Xe2 -excimer lamp for 30 min in an ammonia atmosphere through a mask with holes 100 pm in diameter and center-to-center distance 300 pm C PE irradiated with Ar ions (energy 150 keV, ion dose lO ions/cm ) through a mask with holes 100 pm in diameter and center-to-center distance 200 pm fullerenes Qo deposited through a mask with rectangular holes with an average size of 128 3 pm per 98 8 pm on glass coverslips. Day 7 after seeding. A native cells in an inverted phase-contrast microscope B, C cells stained with hematoxylin and eosin, Olympus microscope IX 50 D cells stained with fluorescence-based LIVE/DEAD viability/cytotoxicity kit (Invitrogen), Olympus microscope IX 50. Bars 300 pm (A), 200 pm (B, D), Imm (C) [10,11].

Nickel chloride is used in nickel electroplating baths. It also is used to prepare various nickel salts and nickel catalysts and in industrial gas masks to protect from ammonia. 

Since the use of ammonia is not practical in transition metal catalyzed processes, the identification of its synthetic equivalents is of major importance. Benzophenone imine was found to couple with 3-bromopyridine readily under the above mentioned conditions (7.72.), The masking benzophenone was removed in transamination with hydroxylamine, which gave the desired 3-aminopyridine in 81% overall yield.92 Allylamine was also successfully employed as ammonia equivalent93... 

To measure hardness, the sample is treated with ascorbic acid (or hydroxylamine) to reduce Fe3+ to Fe2+ and with cyanide to mask Fe2+, Cu+, and several other minor metal ions. Titration with EDTA at pH 10 in NH3 buffer then gives the total concentrations of Ca2+ and Mg2+. Ca2+ can be determined separately if the titration is carried out at pH 13 without ammonia. At this pH, Mg(OH)2 precipitates and is inaccessible to EDTA. Interference by many metal ions can be reduced by the right choice of indicators.21... 

---