HazMat Tool — substance information

tert-Butyl hypochlorite

HMT May 2026

UN / ID: UN 3255
Hazard class: 4.2
Packing group: I
ERG guide: ERG 135
Special provisions: —
Source: 49 CFR §172 (2026/05)

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tert-Butyl hypochlorite

tert-Butyl hypochlorite is the organic compound with the formula (CH3)3COCl. A yellow liquid, it is a rare example of an organic hypochlorite, i.e. a compound with an O-Cl bond. It is a reactive material that is useful for chlorinations. Wikipedia

Emergency Response Guide No. 135

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

(3) Hazard Class

4.2
Spontaneously combustible materials

(4) Identification number

UN 3255

(5) Packing Group

(6) Labels

Spontaneously combustible materials (4.2)

(7) Special Provisions (§172.102)

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	211	see 49 CFR §173.211
(8C) Bulk	243	see 49 CFR §173.243

(9) Quantity Limits

(9A) Passenger aircraft/rail	Forbidden
(9B) Cargo aircraft only	Forbidden

(10) Vessel stowage

(10A) Location

Stowage category “D” means the material must be stowed “on deck only” on a cargo vessel or on a passenger vessel carrying a number of passengers limited to not more than the larger of 25 passengers or one passenger per each 3 m of overall vessel length, but the material is prohibited on a passenger vessel in which the limiting number of passengers is exceeded.

Source: 49 CFR §172.101(k)

(10B) Other

40	see 49 CFR §176.84

Source: 49 CFR §176.84

Segregation chart for load, transport, and storage

This chart shows whether loading, transport, or storage with other hazard classes is permitted, prohibited, or restricted. Based on 49 CFR §177.848.

Hazard class	8	7	6.1	5.2	5.1	4.3	4.2	4.1	3	2.3B	2.3A	2.2	2.1	1.6	1.5	1.4	1.3	1.1/1.2
1.1/1.2
1.3
1.4
1.5
1.6
2.1
2.2
2.3A
2.3B
3
4.1
4.2
4.3
5.1
5.2
6.1
7
8

	Must not be loaded, transported, or stored together in the same vehicle or facility.
	May be loaded, transported, or stored together.
	May be loaded, transported, or stored together only with restrictions.

Similar substances

UN / ID	Proper shipping name	Hazard class
UN 3487	Calcium hypochlorite, hydrated, corrosive or Calcium hypochlorite, hydrated mixture, corrosive with not less than 5.5% but not more than 16% water	5.1
UN 2880	Calcium hypochlorite, hydrated or Calcium hypochlorite, hydrated mixture, with not less than 5.5% but not more than 16% water	5.1
UN 3485	Calcium hypochlorite, dry, corrosive or Calcium hypochlorite mixture, dry, corrosive with more than 39% available chlorine (8.8% available oxygen)	5.1
UN 1748	Calcium hypochlorite, dry or Calcium hypochlorite mixture dry with more than 39% available chlorine (8.8% available oxygen)	5.1
UN 3486	Calcium hypochlorite mixture, dry, corrosive with more than 10% but not more than 39% available chlorine	5.1
UN 2208	Calcium hypochlorite mixture, dry, with more than 10% but not more than 39% available chlorine	5.1
UN 2741	Barium hypochlorite with more than 22 percent available chlorine	5.1
UN 1471	Lithium hypochlorite, dry or Lithium hypochlorite mixture	5.1
UN 1462	Chlorites, inorganic, n.o.s	5.1
UN 3212	Hypochlorites, inorganic, n.o.s	5.1
	Silver chlorite (dry)	Forbidden
UN 1453	Calcium chlorite	5.1
UN 1908	Chlorite solution	8
UN 1496	Sodium chlorite	5.1
UN 1791	Hypochlorite solutions	8