IUPAC Name: beryllium difluoride  
Synonyms of Beryllium fluoride (CAS NO.7787-49-7): Beryllium difluoride ; Beryllium fluoride (BeF2) ; Beryllium fluoride(Be2F4) ; Beryllium fluoride(BeF2) ; EINECS 232-118-5  HSDB 355 ; NSC 84264 ; Beryllium fluoride [Beryllium and beryllium compounds]
CAS NO: 7787-49-7   
Molecular Formula of Beryllium fluoride (CAS NO.7787-49-7): Be-F₂ 
Molecular Weight: 47.009   
Molecular Structure:

 Beryllium fluoride together tend to bind to ATP sites and inhibit protein action, making it possible to crystallise proteins in the bound state. Beryllium fluoride is used in biochemistry, particularly protein crystallography as a mimic of phosphate. Thus, ADP.
 Beryllium fluoride is the best neutronic properties of fluoride salt combinations appropriate for reactor use. Beryllium fluoride is used in liquid-fluoride nuclear reactors. Typically beryllium fluoride is mixed with lithium fluoride to form a base solvent. Into Beryllium fluorides of uranium and thorium are introduced. Beryllium fluoride is exceptionally chemically stable and LiF/BeF2 mixtures have low melting points.

 Tetrafluorberyllate is a robust ion, which allows its purification by precipitation of various impurities as their hydroxides. Heating purified (NH4)2BeF4 gives the desired product:
(NH₄)2BeF₄ → 2NH₃ + 2HF + BeF₂

NTP 10th Report on Carcinogens. IARC Cancer Review: Group 1 IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 58 (1993),p. 41.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Human Sufficient Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 58 (1993),p. 41.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Animal Sufficient Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 1 (1972),p. 17.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Animal Sufficient Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 23 (1980),p. 143.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Animal Sufficient Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 58 (1993),p. 41.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) . Beryllium and its compounds are on the Community Right-To-Know List. Reported in EPA TSCA Inventory.

Hazard Codes of Beryllium fluoride (CAS NO.7787-49-7): N,T+,Xi
Risk Statements: 51/53-49-48/23-43-36/37/38-26-25
R51/53: Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
R49: May cause cancer by inhalation. 
R48: Danger of serious damage to health by prolonged exposure. 
R23: Toxic by inhalation. 
R43: May cause sensitization by skin contact. 
R36/37/38: Irritating to eyes, respiratory system and skin. 
R26: Very toxic by inhalation. 
R25: Toxic if swallowed.
Safety Statements: 61-53-45 
S61: Avoid release to the environment. Refer to special instructions / safety data sheets. 
S53: Avoid exposure - obtain special instructions before use. 
S45: In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)
RIDADR: UN1566
Hazard Note: Irritant
HazardClass: 6.1
PackingGroup: II
Confirmed carcinogen with experimental carcinogenic and tumorigenic data by inhalation. Poison by ingestion, subcutaneous, intravenous, and intraperitoneal routes. See also BERYLLIUM COMPOUNDS and FLUORIDES. Incompatible with Mg. When heated to decomposition, it emits very toxic fumes of BeO and F⁻.

OSHA PEL: TWA 0.002 mg(Be)/m³; STEL 0.005 mg(Be)/m³/30M; CL 0.025 mg(Be)/m³
ACGIH TLV: TWA 0.002 mg(Be)/m³; Confirmed Human Carcinogen; (Proposed: TWA 0.0002 mg(Be)/m³ (sensitizer); Confirmed Human Carcinogen); TWA 2.5 mg(F)/m³; BEI: 3 mg/g creatinine of fluorides in urine prior to shift; 10 mg/g creatinine of fluorides in urine at end of shift.
NIOSH REL: (Beryllium) CL not to exceed 0.0005 mg(Be)/m³